Radiometer ABL-700, ABL-800 Reference manual

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ABL700 series reference manual

ABL700

series

reference

manual

Note to the users of the EML105, ABL5xx, ABL SYSTEM 6xx,

ABL7xx Series, ABL800 FLEX and ABL800 BASIC analyzers

Introduction

Brief overview of the change

This note to users outlines a change in the operator’s and reference manual for your EML105, ABL5xx, ABL SYSTEM 6xx, ABL7xx Series, and/or ABL800 FLEX and ABL800 BASIC analyzer.

Operator’s manual:

Limitations of use and known interfering substances:

CAUTION - Known interfering substances

Substance Interference

–

ClO

(drugs) For ClO

– ,

interference on cCa2+ (1.25 mmol/L

level) has been detected:

(1.25 mmol/L level): 0.20*.

cCa

Technical documentation

Instructions to user

* Depending on the pH level

Reference manual:

Change/Description

Interference on

For ClO detected. The interference results for ClO

– ,

interference on cCa2+ (1.25 mmol/L level) has been

–

are as follows:

Interference on…

Substance Test Conc. cK+

(4 mmol/L

level)

–

ClO

1.5 mmol/L - -

* Depending on the pH level A "-" indicates that interference has not been measured on the respective parameter.

cNa

(150 mmol/L

level)

(1.25 mmol/L

cCa

level)

0.20*

(110 mmol/L

cCl

level)



8-30

The manual will be updated with the above information as part of the next manual update.

Please place this note to the users in the binder of your manual.

Note to users of the ABL700 Series analyzers

Mandatory upgrade of the manual

Cleaning solution with cleaning additive installation

The manuals for the ABL700 Series analyzers must be upgraded with regard to the information on cleaning solution.

The procedure for adding cleaning additive has been changed for the abovementioned analyzers and from now on the following instructions must be followed:

Remove the foil from the DosiCapZip and unscrew it (Figs. 1+2).

Turn the DosiCapZip upside down and screw it onto the container again (Figs. 3+4).

TCAUTIONT: TIf the contents of the DosiCapZip or the container have

been spilt by accident, both the container and the DosiCapZip should be

discarded to prevent incorrect concentrations in the solution.

Invert the container at least 20 times to dissolve the additive (Fig. 5).

Place the container horizontally so that the solution may enter the

DosiCapZip and leave it for 3 minutes (Fig. 6).

Invert the container again at least 20 times to fully dissolve the additive (Fig. 7).

Unscrew the lid from the new solution container.

Remove the used solution container by holding it on the sides and pulling.

Scan the barcode of the new solution, using the barcode reader.

Place the new solution container in position on the analyzer and push it firmly onto the connector as far as possible.

10.

For the ABL700 Series analyzers, sw. 3.836: Press Restart to restart the analyzer.

For the ABL700 Series analyzers, sw. 6.00: Press Restart and Accept to

restart the analyzer.

Cleaning solution with cleaning additive – general information

Cleaning Solution 175 mL 944-123 S7375

Use: For cleaning the measuring system of the ABL700 Series analyzers. Contains: Salts, buffer, anticoagulant, preservatives, surfactants and enzyme.

Safety Data Sheet may be obtained from your local distributor.

Item Code No. Type

Storage: At 2-10 °C. Stability in use: The Cleaning Solution with the Cleaning Additive is stable for 2

months in use.

Analyzer: Perform cleaning every 8th hour.

T CAUTION – Risk of personal injury

TDo not breathe dust (S22). Avoid contact with skin (S24). Irritating to eyes and

skin (R36/38). Wear suitable gloves (S37). May cause sensitization by inhalation and skin contact (R42/43). In case of accident or if you feel unwell, seek medical advice immediately (show the label where possible) (S45).

Texts no longer valid in the manuals

Due to new cleaning solutions, information about Cleaning solution S7370 and Cleaning additive S5370 is no longer valid.

Below is a list of the sections in the manual that must be ignored.

ABL700 Series reference manual:

Technical documentation

Instructions to user

Chapter 7: Solutions and gas mixtures: S7370 Cleaning Solution and

S5370 Cleaning additive:

Text no longer relevant.

See instruction about the new Cleaning Solution S7375 above instead.

Index: Cleaning Additive references no longer

relevant.

The manuals for the ABL700 Series analyzers will be updated with the above information when reprinted.

This update kit includes a note to the user with the changes and a new date of issue page of the manual. Please place the note to the user in the binder of the ABL700 Series reference manual and replace the date of issue page with the new corresponding page, then discard the old page.

Reference

ABL700 Series

1. Introduction

2. Electrodes

3. The Optical System

Contents

Manual

4. User-defined Corrections

5. Performance Characteristics

6. Parameters

7. Solutions

8. Interfacing Facilities

Index

Date of Issue

SYSTEM PERFORMANCE AND WARRANTY DISCLAIM

Radiometer cannot provide or verify instrument performance characteristics and accept warranty claims or product liability claims if the recommended procedures are not carried out, if accessories other than those recommended by Radiometer are used, or if instrument repairs are not carried out by authorized service representatives.

The instructions given in the Operator’s Manual for the ABL700 Series must be observed in order to ensure proper instrument performance, and to avoid electrical hazards.

TRADEMARKS

ABL™, BMS™, FLM™, CMT™, Deep Picture™, QUALICHECK™ and RADIOMETER™ are trademarks of Radiometer Medical ApS, Denmark.

ABL is registered in the USA. QUALICHECK is registered in the USA and in some other countries.

The contents of this document may not be reproduced in any form or communicated to any third party without the prior written consent of Radiometer Medical ApS.

While every effort is made to ensure the correctness of the information provided in this document Radiometer Medical ApS assumes no responsibility for errors or omissions which nevertheless may occur.

ABL700 Series Reference Manual Contents

1. Introduction .............................................................................................. 1-1

ABL700 Series Documentation .................................................................. 1-2

Warnings/Cautions and Notes .................................................................... 1-3

2. Electrodes.................................................................................................. 2-1

General Construction .................................................................................. 2-2

General Measuring Principles..................................................................... 2-3

Calibration .................................................................................................. 2-7

Electrode Measuring Time and Updatings ............................................... 2-14

Reference Electrode.................................................................................. 2-15

pH Electrode ............................................................................................. 2-16

pCO

Electrode ......................................................................................... 2-23

Electrode............................................................................................ 2-32

Electrolyte Electrodes ............................................................................... 2-42

Metabolite Electrodes ............................................................................... 2-54

References................................................................................................. 2-64

3. The Optical System ................................................................................... 3-1

Measuring Principle.................................................................................... 3-2

Correcting for Interferences........................................................................ 3-7

Calibration .................................................................................................. 3-9

Measurement and Corrections .................................................................. 3-10

References................................................................................................. 3-13

4. User-Defined Corrections ......................................................................... 4-1

General Information.................................................................................... 4-2

Correction Factors for Oximetry Parameters and Bilirubin........................ 4-4

Electrolyte and Metabolite Parameters ....................................................... 4-8

5. Performance Characteristics.................................................................... 5-1

General Information.................................................................................... 5-2

Definition of Terms and Test Conditions ................................................... 5-3

Reference Methods for the ABL700 Series ................................................ 5-8

ABL735/30/25/20/15/10/05 Performance Test Results - Macromodes.... 5-10

ABL735/30/25/20/15/10/05 Performance Test Results - Micromodes .... 5-19

ABL700 Performance Test Results .......................................................... 5-30

ABL735/30/25/20/15/10/05/00 Expired Air Mode .................................. 5-32

ABL735/30/25/20/15/10/05/00 Capillary - pH Only Mode ..................... 5-35

Contents ABL700 Series Reference Manual

ABL735/30 Performance Test Results - Bilirubin.................................... 5-36

Interference Tests...................................................................................... 5-42

References................................................................................................. 5-50

6. Parameters ................................................................................................. 6-1

General Information.................................................................................... 6-2

Acid-base Parameters.................................................................................. 6-6

Oximetry Parameters .................................................................................. 6-8

Oxygen Parameters ..................................................................................... 6-9

Bilirubin.................................................................................................... 6-13

Electrolyte Parameters .............................................................................. 6-14

Metabolite Parameters .............................................................................. 6-15

Units and Ranges for Measured Parameters ............................................. 6-16

Units and Ranges for Input Parameters .................................................... 6-19

Units and Ranges for Derived Parameters ................................................ 6-20

List of Equations....................................................................................... 6-25

Oxyhemoglobin Dissociation Curve (ODC)............................................. 6-41

Conversion of Units.................................................................................. 6-46

Default Values .......................................................................................... 6-48

Altitude Correction ................................................................................... 6-49

References................................................................................................. 6-50

7. Solutions and Gas Mixtures ..................................................................... 7-1

General Information.................................................................................... 7-2

S1720 and S1730 Calibration Solutions ..................................................... 7-3

S4970 Rinse Solution ................................................................................. 7-4

S7370 Cleaning Solution and S5370 Cleaning Additive............................ 7-5

S7770 tHb Calibration Solution.................................................................. 7-6

Gas Mixtures (Gas 1 and Gas 2) ................................................................. 7-7

Electrolyte Solutions................................................................................... 7-8

S5362 Hypochlorite Solution ..................................................................... 7-9

Certificates of Traceability ....................................................................... 7-10

8. Interfacing Facilities ................................................................................. 8-1

Connecting a Mouse ................................................................................... 8-2

Connecting an Alphanumeric Keyboard..................................................... 8-3

Connecting the Bar Code Reader................................................................ 8-4

Connecting a Network ................................................................................ 8-6

Index

Date of Issue

ABL700 Series Reference Manual 1. Introduction

1. Introduction

Overview

This section gives an introduction to the documentation that accompanies your ABL700 Series analyzer. It describes how this particular manual is organized and explains the different notices that appear in it.

Contents

This chapter contains the following topics.

ABL700 Series Documentation ....................................................................... 1-2

Warnings/Cautions and Notes.......................................................................... 1-3

1-1

1. Introduction ABL700 Series Reference Manual

ABL700 Series Documentation

ABL700 Series Analyzers

Documentation

The documentation that accompanies the ABL700 Series analyzers covers the series in general - each possible electrode combination is not considered individually.

The table below describes the documentation that comes with each analyzer.

Documentation Description

Design of Manual

The Operator’s Manual

Contains all the information required for everyday operation of the analyzer.

Describes the functions of the analyzer and how to set it up according to customer needs and requirements.

Explains error messages and gives troubleshooting procedures.

Contains ordering information

The Reference Manual

Gives detailed information about the operating principles of the analyzer.

Describes the measuring and calibrating principles.

Lists all the parameters.

Gives the equations from which the derived parameters are calculated.

Gives information about how the performance of the analyzer is tested.

On-line Help Summarizes the information found in the Operator’s

Manual.

Gives hands-on help at the analyzer.

Depending on the set up of your analyzer, the entire Reference Manual may not be applicable to it. However the manual is designed in such a way that it is easy to disregard or remove the sections that are not relevant to your instrument.

1-2

ABL700 Series Reference Manual 1. Introduction

Warnings/Cautions and Notes

Definitions

List of

WARNING/ CAUTION

Notices

The following table indicates the type of information given in warnings, cautions, and notes:

Notice Definition

WARNING

Warnings alert users to potentially serious outcomes to

selves or to the patient (such as death, injury, or serious

them adverse events).

PRECAUTION

Precautions alert users to exercise the special care necessary for safe and effective use of the device. They

may include actions to be taken to avoid effects situations on patients or users that may not be potentially life threatening or result in serious injury , but about which the user should be aware. Precautions may also alert the user to adverse effects on the device caused by use or misuse, and the care required to avoid such effects.

NOTE

Notes give practical information.

All WARNING/CAUTION notices that appear in this manual, are listed below.

S5370 Cleaning Additive: May cause sensitization by inhalation and skin

•

contact). Do

not breathe dust. Avoid contact with skin. Wear suitable gloves.

In case of accident or if you feel unwell, seek medical advice immediately (show the label where possible).

Gas Mixtures: Not for drug use. High pressure gas. Do not puncture. Do not

•

store near heat or open flame - exposure to temperatures above 52 C

(125 F) may cause contents to vent or cause bursting. Not for inhalation. Avoid

breathing gas - mixtures containing carbon dioxide

can increase respiration and heart rate. Gas mixtures containing less than

19.5 % oxygen can cause rapid suffocation. Store with adequate ventilation. Avoid contact with oil and grease. Only use with equipment rated for cylinder pressure. Use in accordance with Safety Data Sheet.

1-3

Introduction

Contents

2. Electrodes

This chapter describes the construction, measuring principle and calibration process for each of the electrodes in the ABL700 Series analyzers.

General sections covering the background theory used for measurements and calibrations are also presented here.

This chapter contains the following topics.

General Construction ....................................................................................... 2-2

General Measuring Principles .......................................................................... 2-3

Calibration........................................................................................................ 2-7

Electrode Measuring Time and Updatings....................................................... 2-14

Reference Electrode ......................................................................................... 2-15

pH Electrode .................................................................................................... 2-16

Electrode................................................................................................. 2-24

pCO

Electrode ................................................................................................... 2-33

Electrolyte Electrodes ...................................................................................... 2-43

Metabolite Electrodes....................................................................................... 2-55

References........................................................................................................ 2-65

2. Electrodes ABL700 Series Reference Manual

General Construction

An Electrode

In this manual and other Radiometer literature, the term electrode refers to the whole sensor unit, i.e. both the electrode and the electrode jacket. Radiometer electrodes are cordless, thereby limiting the level of noise picked up during the measuring process. The electrical signals from the electrodes are amplified by preamplifiers placed in each module.

A generalized diagram of a Radiometer electrode is given below.

Electrolyte solution

Electrical contact

Color-coded ring

Electrode jacket

Membrane

The main electrode parts are described below.

Part Description

Electrical contact Provides electrical contact between the electrode and the

analyzer.

Color-coded ring Marks each electrode for easy recognition.

Electrode jacket Holds the electrolyte solution and membrane, and protects

the electrode.

Membrane A thin sheet-like material to separate the sample from the

electrode, that differentiates between the substances allowed to pass through it towards the electrode.

2-2

Electrolyte solution

A conducting solution to provide an electric contact between the electrode and the sample (also known as a salt-bridge solution).

More specific descriptions of the electrodes are found under the appropriate electrode titles in this chapter.

ABL700 Series Reference Manual 2. Electrodes

General Measuring Principles

Introduction

There are two different measuring principles employed for electrodes in the ABL700 Series.

• Potentiometry: The potential of an electrode chain is recorded using a

voltmeter, and related to the concentration of the sample (the Nernst equation).

• Amperometry: The magnitude of an electrical current flowing through an

electrode chain, which is in turn proportional to the concentration of the substance being oxidized or reduced at an electrode in the chain.

These two measuring principles are described in detail on the following pages.

Potentiometric Method

An electrode chain describes an electrical circuit consisting of a sample, electrode, reference electrode, voltmeter, membranes, and electrolyte solutions.

Voltmeter

Reference

electrode

Electrolyte

solution

Membrane

Sample

Electrolyte

solution

Membrane

Electrode

Every element in the electrode chain contributes a voltage to the total potential drop through the chain. Thus:

• When immersed in the appropriate electrolyte solution, both electrodes have

separate potentials.

• The membrane junctions between the sample and electrolyte solutions also have

separate potentials.

The complete electrode chain potential therefore, is the sum of these separate potentials and is the quantity measured by the voltmeter.

E = E – E

total sample Ref

where the final unknown potential (E electrode chain potential (E

) and the reference potential (E

total

) can be calculated knowing the total

sample

that is constant

Ref

between two subsequent calibrations).

Continued on next page

2-3

2. Electrodes ABL700 Series Reference Manual

General Measuring Principles, Continued

Potentiometric Method

(continued)

Having measured the unknown potential (E applied to determine the activity (a

) of the species under study:

sample

where:

R =

T n

F =

= standard electrode potential

gas constant (8.3143 JK

= absolute temperature (310 K (37

= charge on the ion

Faraday constant (96487 C mol

= activity of

−1

mol−1)

The Nernst equation is rearranged to express the activity as a function of the potential

. Having measured E

sample

the activity can be calculated since all

sample

other quantities are already known. Finally the analyzer converts activity to concentration.

), the Nernst equation is then

sample

23R

log

−1

C ))

)

Strictly speaking, in potentiometry the potential of an electrode chain or the magnitude of current flowing through an electrical chain is related to the activity of a substance, and not its concentration.

Activity expresses the ‘effective concentration’ of a species, taking non-ideality of the medium into account.

Activity and concentration are related by the following equation:

= γ c

where:

= the activity of the species x

= the activity coefficient of species x under the measurement conditions

(for ideal systems

= the concentration of species x (mmol/L)

γ = 1)

NOTE:

To be exact, activity is related to the molality of species x, i.e., the number of mmoles per kg of solvent. However molality is converted to concentration (molarity).

ABL700 Series analyzers automatically convert activities into concentrations

[1].

The term concentration is therefore used in explanations of the measuring principles for each of the electrodes further on in this chapter.

2-4

The potentiometric measuring principle is applied in the pH,

pCO

electrodes. It is slightly different for the

electrode, however, since the Nernst

equation is not directly applied.

pCO

, and electrolyte

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

General Measuring Principles, Continued

Amperometric Method

The electrode chain in amperometric measurements consists of the sample, the two electrodes (anode and cathode), an amperemeter, a voltage source, the membranes, and the electrolyte solutions.

Applied voltage

Anode Cathode

Electrolyte solution

Sample

mperemeter

Membrane

Part Function

Cathode Negative electrode where a reduction reaction occurs and

electrons are consumed.

Anode Positive electrode where an oxidation reaction occurs and

electrons are released.

Electrolyte

Provides electrical contact between the anode and cathode.

solution

Membrane Allows the appropriate molecules to pass through from the

sample.

Sample Contacts the membrane.

Applied voltage Applies the necessary potential for the reduction or oxidation

reaction under study.

Amperemeter Measures the current flowing through the circuit.

To simplify the description of the measuring process in an amperometric electrode, we make the following assumptions:

• there is a species A in the sample which is reduced at the cathode to A

• there is a species X in the electrolyte which is oxidized at the anode to X

−

Continued on next page

2-5

2. Electrodes ABL700 Series Reference Manual

General Measuring Principles, Continued

Amperometric Method (continued)

The membrane is selective to the species A, allowing no other species but it to pass

through from the sample into the electrolyte solution.

As an appropriate potential is applied across the electrodes, the species

A is

reduced at the cathode according to the following reaction:

A + e

−

→ A

−

The reduction of A produces a flow of electrons, i.e. an electrical current.

To complete the electrical circuit an oxidation reaction where electrons are released is necessary. Therefore species

X is oxidized according to the following

reaction:

→ X

+ e

−

The magnitude of the current flowing through the circuit is proportional to the concentration of the species being reduced, in this case species thereby automatically calculates the concentration of

A in the sample.

A. The analyzer

The amperometric measuring principle is applied in the electrodes.

, glucose, and lactate

2-6

ABL700 Series Reference Manual 2. Electrodes

−

Calibration

Actual Electrode Condition

Calibration Line

The electrodes are active elements and must be calibrated regularly as the signals from the electrodes change with, e.g. age or deposits on the membrane.

Calibration relates the electrode signals during the calibration sequence to the values of the calibrating solutions and must be performed at regular intervals so that the accuracy can be constantly refined after inevitable minor changes in the electrodes’ behavior.

Actual electrode condition is described by status/zero point and sensitivity and compared with theoretical conditions for an "ideal" electrode. In addition to status and sensitivity, an electrode condition is described by drift.

The calibration line expresses the relationship between the potential (or current) measured at an electrode, and the concentration of the species specific to the electrode. The calibration line forms the basis of the scale used by the analyzer to convert electrode chain potentials to concentrations. Each electrode has a different calibration line.

The pH electrode is used as an example to illustrate how this line is derived from two calibration solutions of known pH.

• Cal 1 solution has a pH of 7.398 that gives potential reading of −100 mV.

• Cal 2 solution has a pH of 6.802 that gives a potential reading of −64 mV.

These two values are plotted on a graph.

The relationship between potential and pH is linear so a line can be drawn between the two points, as shown below:

Measured potential (mV)

Calibration line

7.398

pH of Cal 1 sol.

100

6.802

pH of Cal 2 sol.

7.346

pH of sample

The calibration line now forms the scale used to convert the potential measured at the pH electrode during sample analysis to an actual pH value.

Continued on next page

2-7

2. Electrodes ABL700 Series Reference Manual

Calibration, Continued

Calibration Line (continued)

A blood sample gives a potential reading of -97 mV at the pH electrode. Reading off from the calibration line shown below, this potential corresponds to a pH of

7.346.

Measured potential (mV)

−

Theoretical Calibration Line

Calibration line

7.398

pH of Cal 1 sol.

−

100

6.802

pH of Cal 2 sol.

7.346

pH of sample

The calibration line is updated at every calibration. Drift describes the variation in the calibration line between consecutive calibrations.

The theoretical calibration line is the relationship between potential and concentration in a potentiometric measurement, or the relationship between current and concentration in an amperemetric measurement.

In the ABL700 Series the theoretical calibration line for pH is defined by the following two points:

pH Electrode potential

(vs. Ref. potential)

6.800

7.400

Measured potential (mV)

−75.5 mV

−112.4 mV

2-8

−75.5

−112.4

6.8

7.4

The position and slope of the calibration line compared to the theoretical calibration line are described by the status and sensitivity respectively.

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

Calibration, Continued

Sensitivity

Electrode sensitivity expresses how a real electrode measures compared with the specified values of the calibration material; it illustrates the slope of the calibration line derived from a 2-point calibration as a percentage (or fraction) of the slope of the theoretical calibration line, as determined by the Nernst equation of the ion in question.

Calculating the sensitivity is a way of monitoring the deviation of the electrode sensitivity from the theoretical value.

Calculation of the sensitivity is shown, using the pH electrode as an example.

A theoretical calibration line for the pH electrode with a slope of

−61.5 mV/pH is

drawn:

Measured potential (mV)

75.5

−

Theoretical calibration line

112.4

−

6.8

7.4

The calibration line from a 2-point calibration is superimposed on the same graph:

Measured potential (mV)

−

75.5

2-point calibration line Slope = −58.4 mV/pH Sensitivity = 95 %

Theoretical calibration line

112.4

−

6.8

Slope= −61.5 mV/pH Sensitivity = 100 %

7.4

The sensitivity of the electrode is calculated as the ratio between the slope of the 2point calibration line and that of the theoretical line, expressed as a percentage or fraction.

If the theoretical calibration line is assumed to have a sensitivity of 100 %, the 2point calibration line shown in the example will have a sensitivity of approximately 95 %.

Continued on next page

2-9

2. Electrodes ABL700 Series Reference Manual

Calibration, Continued

Sensitivity (continued)

Status

The sensitivity limits for the calibration are set for each electrode. If the sensitivity of any electrode falls outside the allowed limits, the message

out of range

appears in the Calibration Messages, with the particular electrode

Calibration Sensitivity

specified.

The electrode status is a measure of zero point of a complete electrode chain. Status of a real electrode reflects deviations from the conditions of a theoretical electrode, and define the position of the calibration line.

Calculating the status value of an electrode is a way of monitoring the position of the calibration line despite the fact that only a 1-point calibration has been carried out. The calculation of the status is shown, using the pH electrode as an example.

A calibration line with the same slope as the theoretical calibration line (

−61.5

mV/pH) is drawn through this point. This theoretical calibration line is used since no 2-point calibration is performed which would otherwise give an actual calibration line.

Measured potential (mV)

Theoretical calibration line with a slope = −61.5 mV/pH drawn through

Cal 1

A pH of 7.400, the nominal pH of Calibration Solution 1 (pH corresponding potential (

) is read off the theoretical calibration line that

Cal 1 nom

the point from a 1-point calibration.

Cal 1

) is chosen. Its

Cal 1 nom

was drawn through the 1-point calibration point.

Measured potential (mV)

Theoretical calibration line for the theoretical pH electrode with known potential of −112.4 mV at a pH =

7.400.

2-10

Cal 1 nom(theo)

E=−112.4 mV

Cal 1 nom

Cal 1

∆pH

∆

Theoretical calibration line drawn through the 1point calibrat ion point.

Status

Cal 1 nom

(7.400)

Cal 1

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

−

Calibration, Continued

Status (continued)

A line from pH corresponding potential (

is extrapolated up to the theoretical calibration line, and the

Cal 1 nom

Cal 1 nom(theo)

) read off the theoretical calibration line.

Calibration Materials

The difference between

Cal 1 nom

and E

Cal 1 nom(theo)

which corresponds to ∆E on the

graph, represents the potential that should theoretically be obtained for a solution with pH = 7.400. This potential difference (

∆E) thus describes the deviation of the

actual pH reference electrode system from a theoretical electrode system. Similarly

∆pH describes the deviation in pH values that would be produced

between measurements with an actual electrode system and measurements with a theoretical electrode system.

The status of the pH electrode, pH(Status), is then calculated as:

pH(Status) = 7.4 +

Cal 1 nom Cal 1 nom(theo)

61.5

The status limits of the calibration are set for each electrode. If the status for any electrode falls outside the allowed limits, the message

appears in the Calibration Messages, with the particular electrode specified.

limits

Calibration status out of

The following calibration materials are used:

Calibration Material Used for...

Calibration Solutions 1 and 2: the exact composition of the calibration solutions is given in the bar code on the bottle label, which can be read into the analyzer using the

Calibration of the pH, and electrolyte electrodes

bar code reader, or entered manually via the keyboard.

Calibration Solution 1: Calibration of the

metabolite electrodes and optical system

Gas 1 and Gas 2: each gas has a precise composition essential for determining the accuracy of the analyzer in

each pCO

and pO

measurement.

Calibration of the

pCO

and pO

electrodes

tHb Calibration Solution: Calibration of the

optical system

The Chemical Reference Laboratory at Radiometer is responsible for the accuracy of the calibrating solutions and gases.

Traceability certificates for individual solutions are presented in Chapter 7 of this

manual.

Continued on next page

2-11

2. Electrodes ABL700 Series Reference Manual

Calibration, Continued

Drift

Drift is defined as the difference measured by the electrodes during last and previous calibrations, and is a measure of the electrode stability.

Drift 1 is obtained on Calibration Solution 1 and/or Gas 1 and is calculated as

follows, using the pH electrode as an example:

Measured potential

Calibration line from last 2-point calibration

(mV)

1-point calibration

Drift 1 value

1-point calibration

2-point calibration

Calibration Solution 2

Calibration Solution 1

Drift 2 is obtained after 2-point calibration. The pH electrode is used as an

example and the calibration schedule is set so that each 2-point calibration is separated by two 1-point calibrations.

Measured potential (mV)

Drift 2

Calibration line from 2

Slope of 1

Calibration line from 1

2-point calibration

2-point calibration line

2-point calibration

1-point calibration

Calibration Solution 2

Calibration Solution 1

Drift tolerances express the extent to which drift values for an electrode can fluctuate before the electrode is deemed unstable and thus incapable of providing reliable calibrations.

The drift tolerances for each electrode are set in the analyzer’s Setup programs. Radiometer recommends the use of the default drift tolerances, as too narrow drift tolerances will cause electrode drift errors even for normal electrode fluctuations. If the drift tolerances are too wide, significant measurement errors will result without warning.

Continued on next page

2-12

ABL700 Series Reference Manual 2. Electrodes

Calibration, Continued

Drift (continued)

If the drift values for any electrode fall outside the drift tolerances, the message

Calibration drift out of range appears in the Calibration Messages, with the

particular electrode specified.

No drift values are reported for startup calibrations as there are no previous calibrations available for comparison.

2-13

2. Electrodes ABL700 Series Reference Manual

Electrode Measuring Time and Updatings

Measuring Time

Updatings

In the ABL700 Series analyzers the measuring time of the electrode is independent of the electrode type. Electrode signals are registered at 0.982 second intervals during both calibrations and measurements. The registration of each electrode signal begins after the samples, calibration solutions, and calibration gases are in position in the measuring modules.

The duration of each calibration is predetermined, as is the number of updatings of the electrodes’ signals.

In general, the updatings from an electrode response are numbered from 1 to upd last, where updating number 1 is the first updating and upd last is the last. The

diagram below schematically illustrates the electrode response that is calculated on uncorrected electrode updating values in the ABL700 Series.

Signal

Upd 1 Upd last

Updatings

2-14

ABL700 Series Reference Manual 2. Electrodes

Reference Electrode

Electrode Description

The reference electrode is used in the measurement of pH and electrolyte parameters and is located in the pH/Blood Gas module.

The reference electrode maintains a stable, fixed potential against which other potential differences can be measured. The potential is not altered by sample composition.

A fixed potential is maintained at the reference electrode by the following equilibrium reactions:

AgCl ⇔ Ag + Cl

+ −

Ag + e ⇔ Ag

+ −

These reactions are possible because the electrode is made from a Ag rod coated with Ag to provide the Ag/Ag

equilibrium and determine the reference potential.

Electrode contact

The electrolyte solution acts as a salt-bridge solution that maintains an electrical contact between the coated Ag wire and the sample.

Rubber ring

The solution is 4 M sodium formate (HCOONa), adjusted to pH 5.5 with hydrochloric acid.

The chloride concentration in the electrolyte

Electrolyte

solution is adjusted in accordance with the chloride concentration in the rinse solution,

g rod coated with Ag

to reduce Cl

−

exchange across the membrane, thereby obtaining a more stable potential.

3-layer membrane

The electrode is encased in the electrode jacket: The rubber ring seals the electrode in the jacket to prevent evaporation or leakage of the electrolyte solution.

The membrane consists of three separate membranes:

Membrane Function

Inner To limit diffusion through the membrane and stabilizes the whole

membrane system.

Middle To prevent protein interference.

Outer To reduce the interchange of sample or rinse solution and

HCOONa solution.

Packaging

The E1001 reference electrode comes in a box with an insert explaining the preparation of the electrode and its use.

2-15

2. Electrodes ABL700 Series Reference Manual

pH Electrode

Description

Electrode Chain Potentials

The pH electrode (E777) is a pH-sensitive glass electrode. The pH-sensitive glass membrane is located at the tip and seals the inner buffer solution with a constant and known pH.

The air bubble allows for expansion of the inner buffer solution when the electrode is thermostatted to 37

The potential difference across the glass membrane is due to a change in the charge balance at the membrane.

The glass membrane is sensitive to

ir bubble

Glass membrane

ions. The metal ions in the glass are exchanged with protons on either side of the membrane, from the inner buffer solution on one side and the sample on the other.

A difference in the ion exchange on either side of the membrane occurs if the H

concentration (and therefore pH) is unequal on both sides. The number of positive and negative ions is no longer equal, so the potential difference across the membrane changes. If the H

concentrations on either side of the membrane are

equal, the potential difference will theoretically be 0 mV.

The total potential across the electrode chain is the sum of the potential differences at each element in the chain:

Element Potential Symbol

Ag/AgCl electrode /electrolyte solution. (Reference electrode)

Known and constant when the Ag/AgCl wire is immersed in the electrolyte solution.

Membrane junction between the electrolyte solution in the reference electrode and the

Known and constant. Independent of sample composition.

sample.

pH-sensitive glass membrane between the sample and the pH

Unknown. Dependent on

sample composition.

electrode.

Ag/AgCl electrode/inner buffer solution (pH electrode)

Known and constant when the Ag/AgCl wire is immersed in the inner buffer solution.

Total potential Measured by the voltmeter. E

Continued on next page

ref

Sample

tot

2-16

ABL700 Series Reference Manual 2. Electrodes

(

++−

=−×

−

pH Electrode, Continued

Electrode Chain Potentials (continued)

Nernst Equation

The unknown potential difference across the pH-sensitive glass membrane is the difference between the measured total potential and the sum of the known potentials:

)

mVEEEE=E

The theoretical sensitivity of the pH electrode at 37

per pH unit, using pH = −log [H

], and converting concentration to activity, the

EMJreftotalsample

C being equal to −61.5 mV

Nernst equation can be expressed as:

Sensitivity

Status

EE615pH m

sample 0

The sensitivity of the pH electrode (SenspH) is obtained from the calibration line obtained from a 2-point calibration on Calibration Solutions 1 and 2 (Cal 1 and Cal

2), and is calculated from the following equation:

Sens(pH)

= (fraction)

[]

Cal1)E(pH,Cal2)E(pH,

pH(Cal1)pH(Cal2)61.5

−×−

where:

E(pH,Cal2) = Potential of the pH electrode chain from a calibration

measurement on Cal 2 solution

E(pH,Cal1) = Potential of the pH electrode chain from a calibration

measurement on Cal 1 solution

−61.5 mV/pH

pH(Cal2)

pH(Cal1)

= Theoretical sensitivity of the pH electrode at 37

= Specific pH of Cal 2 solution

= Specific pH of Cal 1 solution

The sensitivity of the pH electrode should fall between 0.92 - 1.03 or 92 -103 %.

The status of the pH electrode is calculated from the following equation:

Cal1)(pH,ECal1)E(pH,

Status(pH)

pH(Cal1)nom)pH(Cal1, 2

−+

61.5-

where:

E(pH,Cal1) = Potential of the pH electrode chain from a calibration on

Cal 1 solution

(pH,Cal1) = Standard potential of the pH electrode chain with a

nominal pH = 7.4 (the approximate pH of Cal 1 solution)

−61.5 mV/pH

= Theoretical sensitivity of the pH electrode at 37

Continued on next page

2-17

2. Electrodes ABL700 Series Reference Manual

−

pH Electrode, Continued

Status

(continued)

Drift 1

pH(Cal1,nom)

pH(Cal1)

= Nominal pH of Cal 1 solution (pH = 7.4)

= Specific pH of Cal 1 solution

The status of the pH electrode should fall between a pH of 6.7 and 8.1.

Drift 1 is calculated from the following equation:

1(pH)Drift −−

Cal1prev)E(pH,Cal1)E(pH,

prev)Sens(pH,61.5-

[]

prev)pH(Cal1,pH(Cal1)

where:

E(pH,Cal1) = Potential of the pH electrode chain from a calibration

measurement on Cal 1 solution

E(pH,Cal1prev) = Potential of the pH electrode chain from the previous

calibration measurement on Cal 1 solution

−61.5 mV/pH

= Theoretical sensitivity of the pH electrode at 37

E(pH,Cal1) = Potential of the pH electrode chain from a calibration on

Cal 1 solution

Sens(pH,prev) fraction

pH(Cal1)

pH(Cal1,prev)

= Sensitivity of the pH electrode from the previous 2-point

calibration

= pH of Cal 1 solution as specified in the bar code

= pH of Cal 1 solution in the previous calibration

measurement

NOTE: Under normal circumstances, pH(Cal1)−pH(Cal1,prev) = 0. However in

instances where the Cal 1 solution container has been replaced between two consecutive calibrations, pH(Cal1)−pH(Cal1,prev) ≠ 0.

The default drift tolerances set by Radiometer for Drift 1 are ± 0.020.

Drift 2

Drift 2 is calculated from the following equation:

Drift 2(pH)

E(pH,Cal2) E(pH,Cal1prev)

- 61.5 Sens(pH,prev)

−

pH(Cal2) pH(Cal1,prev)=

−−

[]

where:

E(pH,Cal2) = Potential of the pH electrode chain from a calibration on

Cal 2 solution

E(pH,Cal1prev) = Potential of the pH electrode chain from the previous

calibration on Cal 1 solution

Continued on next page

2-18

ABL700 Series Reference Manual 2. Electrodes

pH Electrode, Continued

Drift 2

(continued)

−61.5 mV/pH

Sens(pH,prev) fraction

= Theoretical sensitivity of the pH electrode at 37

= Sensitivity of the pH electrode from the previous 2-point

calibration

Measurement

pH(Cal2)

pH(Cal1,prev)

= pH of Cal 2 solution

= pH of Cal 1 solution used in the previous calibration

The default drift tolerances set by Radiometer for Drift 2 are ± 0.020.

The sample pH is calculated as follows:

pH(sample) =

E(pH,sample) E(pH,Cal1)

61.5 Sens(pH)

−×

−

pH(Cal1)

where:

Parameter Description

E(pH,sample) Potential of the pH electrode chain from a measurement

on the sample.

E(pH,Cal1) Potential of the pH electrode chain from a calibration on

Cal 1 solution.

−61.5 mV/pH

Theoretical sensitivity of the pH electrode at 37

Sens(pH) Relative sensitivity of the pH electrode chain.

pH(Cal) pH of Cal 1 solution.

pH is measured in the following syringe and capillary modes:

Analyzer Syringe Modes Capillary Modes

ABL735/725/715

195 µL

95 µL 85 µL

195 µL

95 µL 55 µL

35-85 µL

ABL730/720/710

85 µL 85 µL

55 µL

35-85 µL

ABL705

165 µL

95 µL 85 µL

165 µL

95 µL 55 µL

35-85 µL

Continued on next page

2-19

2. Electrodes ABL700 Series Reference Manual

pH Electrode, Continued

Measurement

(continued)

Corrections

Analyzer Syringe Modes Capillary Modes

ABL700

85 µL 55 µL

35-85 µL

The measured pH value is then corrected for systematic deviations from the reference method using the following equation:

pH(sample,corr.) = A

× pH(sample) + A

Equation A

where:

pH(sample) = uncorrected pH value of the sample

pH(sample,corr.) = corrected pH value of the sample.

= instrument-dependent correction factor

= instrument-dependent interception constant

NOTE: The 195

Series analyzers which do not have it. It is designated as "195

L is used as the reference measuring mode for those ABL700

L (ref.)" in the

correction tables.

Correction ABL735/725/15 - Syringe modes: equals to….

For all syringe modes, the measured pH value is corrected using Equation A.

µL 95 µL 85 µL

195

0.9964 0.9964 0.9964

0.0164 0.0164 0.0164

2-20

ABL735/725/15 - Capillary modes: equals to….

For the 195 µL, 95 µL and 85 µL modes, the measured pH value is corrected using Equation A. For the 55 µL mode, the measured pH value is first corrected using Equation A and the constants for the 195 µL mode. The obtained result is then used in Equation A as pH(sample) together with the constants for the 55 µL mode to obtain pH(sample,corr).

µL 95 µL 55 µL

195

0.9964 0.9964 1.01379

0.0164 0.0164

−0.1030

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

pH Electrode, Continued

Corrections (continued)

Correction ABL730/720/710 - Syringe modes: equals to…

85 µL

For the 85 µL mode, the measured pH value is corrected using Equation A.

0.9964

0.0164

ABL730/720/710 - Capillary modes: equals to…

For the 85 µL and 55 µL modes the measured pH value is first corrected using equation A and the constants for the 195 µL mode. The obtained result is then used in Equation A as pH(sample) together with the constants for the 85 µL and 55 µL modes to obtain pH(sample,corr).

µL (ref.*) 85 µL 55 µL

195

0.9964 1.0047 1.01379

0.0164

−0.0316 −0.1030

Correction ABL705 - Syringe modes: equals to…

For the 165 µL, 95 µL and 85 µL modes the measured pH value is corrected using equation A.

µL (ref.) 165 µL 95 µL 85 µL

195

0.9964 0.9964 0.9964 0.9964

0.0164 0.0164 0.0164 0.0164

ABL705 - Capillary modes: equals to…

For the 165 µL and 95 µL modes the measured pH value is corrected using equation A. For the 55 µL mode, the measured pH value is first corrected using Equation A and the constants for the 195 µL mode. The obtained result is then used in Equation

A as pH(sample) together with the constants for the 55 µL mode to obtain pH(sample,corr).

µL (ref.) 165 µL 95 µL 55 µL

195

0.9964 0.9964 0.9964 1.0161

0.0164 0.0164 0.0164

Continued on next page

−0.1181

2-21

2. Electrodes ABL700 Series Reference Manual

pH Electrode, Continued

Corrections (continued)

Correction ABL700 - Syringe modes: equals to…

µL

For the 85 µL mode, the measured pH value is first corrected using Equation A.

0.9964

0.0164

ABL700 - Capillary modes: equals to…

For the 55 µL mode, the measured pH value is first corrected using Equation A together with the constants for the 195 µL mode. The obtained result is then used in Equation A as pH(sample) together with the constants for the 55 µL mode to obtain pH(sample,corr).

µL (ref.) 55 µL

195

0.9964 1.0161

0.0164

−0.1181

All ABL700 Series analysers (software 3.83 and higher) Capillary -pH only mode:

Correction Capillary – pH only mode: equals to…

85 µL 55 µL 35 µL

A0 1.015 1.02 1.03

Stability Criteria

The measured pH value is first corrected using Equation A and the constants for the 195 µL mode. The obtained result is then used in Equation A as pH(sample) together with the constants for either the 85 µL, 55 µL or 35 µL modes to obtain pH(sample,corr).

−0.115 −0.153 −0.227

Chapter 5, Performance Specifications for more information on reference

See methods.

The following stability criterion must be met to obtain a stable electrode response during 1- and 2-point

calibration:

pH(limit)i).updpH(sample,last).updpH(sample, ≤−

Continued on next page

2-22

ABL700 Series Reference Manual 2. Electrodes

pH Electrode, Continued

Stability Criteria (continued)

The following stability criterion must be met to obtain a stable electrode response during

measurement:

pH(limit)i).updpH(sample,last).updpH(sample, ≤−

where:

pH(sample,upd.last) = pH value from the last updating with a measurement

on calibration solution or sample. (The last updating is number 30).

pH(sample,upd.i) = pH value for a given updating with a measurement

on calibration solution or sample. (The relationship must be fulfilled for at least one of the updating numbers 20 or 21).

pH(limit) = pH limiting value for the stability criterion (0.005).

2-23

2. Electrodes ABL700 Series Reference Manual

×−=

pCO2 Electrode

Basic Description

The pCO

mounted in a plastic jacket, which is filled with a bicarbonate electrolyte.

electrode (E788) is a combined pH and Ag/AgCl reference electrode

The jacket is covered by a 20 µm silicone membrane moulded on a 50 µm nylon net.

Electrolyte

The net both reinforces the silicone membrane and serves as a spacer in order to trap a

g/AgCl reference band

layer of the electrolyte between the membrane and the glass tip

g wire

of the electrode. The electrolyte also contains glycerol to

ir bubble

prevent collection of air bubbles in the electrode jacket

Membrane

thus improving electrode stability.

Nernst Equation

The membrane allows any uncharged molecules of CO Charged ions such as H

will not pass. Consequently, dissolved CO2 from the

, O2, N2 to pass through it.

sample will diffuse into the thin layer of bicarbonate electrolyte until the equilibrium is reached.

This produces carbonic acid:

O + CO

⇔ H

2CO3

Carbonic acid dissociates according to the following equilibrium reaction:

+−

⇔+

The release of H

HCO H HCO

23 23

ions changes the H+ concentration, and therefore the pH of the

solution on one side of the pH-sensitive glass membrane.

The concentration gradient of H

ions on the other side of the membrane affects the potential difference across the glass membrane. This change in potential across the glass membrane is measured by the voltmeter.

The Nernst equation is used to convert the potential reading into a pH value:

0glass

mV)(pH5.61

where:

= potential difference across the glass membrane

glass

= standard electrode potential

61.5 mV/pH = theoretical sensitivity of the pH electrode at 37

Continued on next page

2-24

ABL700 Series Reference Manual 2. Electrodes

[

(

pCO2 Electrode, Continued

Nernst Equation (continued)

The pH value is related to the partial pressure of CO2 in the sample by the following equation:

log +pK = pH

×p

CO2

HCO

where:

= −log K

, the equilibrium constant for the dissociation of carbonic acid in

water

= solubility coefficient for CO2 in water

Sensitivity

The bicarbonate concentration

HCO

is so large compared to

]

considered constant. At constant temperatures

is also constant. So the

that it can be

[

]

equation can be simplified to:

pH = K' - log CO

where:

K' is a constant incorporating the equilibrium constant for carbonic acid (K

bicarbonate concentration, and the solubility coefficient

−+

HCOH

of the sample is then calculated from the equation above.

pCO

The pCO

electrode is calibrated on two gases with known CO2 content.

Gas 1 contains 5.61 % CO

is the equilibrium constant for carbonic acid.

and Gas 2 contains 11.22 % CO2.

), the

The exact composition of the calibration gases is contained in their bar codes.

The partial pressures of CO

in the gas mixtures Gas 1 and Gas 2 are calculated

from the following equations:

pF BpCO CO

2 2 Gas 1 2

pF BpCO CO

2 2 Gas 2 2

HO kPa() ()Gas Gas11=×−

)

HO kPa() ()Gas Gas22=×−

)

where:

pCO pCO

Gas 1 or 2

(Gas1),

(Gas2)

= Pressure of CO

= Pressure inside the measuring chamber during a

in Gas 1 or Gas 2 respectively

measurement on Gas 1 or Gas 2 respectively

pHO

= Water vapor pressure (6.2571 kPa at 37

Continued on next page

2-25

2. Electrodes ABL700 Series Reference Manual

pCO2 Electrode, Continued

Sensitivity

(continued)

FCO

(Gas1),

(Gas2)

= Fraction of CO

The relative sensitivity of the

Sens( CO

) =

where:

,Gas2)

E(CO

= Potential of the pCO

Gas 2

E(CO

,Gas1)

= Potential of the pCO

Gas 1

in Gas 1 or Gas 2 respectively

pCO

electrode is calculated as follows:

E(CO ,Gas2) E(CO ,Gas1)

Sens( CO , theo) log

−

electrode from a measurement on

CO (Gas2)

CO (Gas1)

Status

Sens(pCO

pCO pCO

(Gas1)

(Gas2)

,theo)

= Theoretical (absolute) sensitivity of the pCO

= Partial pressure of CO

The sensitivity of the pCO

or 85 - 100 %.

The status of the pCO

electrode is calculated as follows:

where:

pCO

(Gas1)

E(CO

,Gas1)

(CO2,Gas1)

= Partial pressure of CO

= Potential of the pCO

= Standard potential of the pCO

at 37

in Gas 1

in Gas 2

electrode should fall between 0.85 -1.00

−

×=

in Gas 1 (see partial pressure

Gas1),(COEGas1),E(CO

202

theo),COSens(

above)

electrode from a measurement on

Gas 1

electrode with Gas 1

electrode

kPa10(Gas1)CO)COStatus(

2-26

Sens(pCO

,theo)

The status of the pCO

kPa).

= Theoretical (absolute) sensitivity of the pCO

electrode should fall between 6.2-260 mmHg /(0.83-34.66

at 37

electrode

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

[

pCO2 Electrode, Continued

Drift

Drift 1 is calculated as follows:

Drift 2 is calculated as follows:

− ×

prev)Gas1,,E(COGas1),E(CO

theo),COSens(prev),COSens(

ppp

−×=

− ×

prev)Gas1,,E(COGas2),E(CO

theo),COSens(prev),COSens(

ppp

−×=

kPa)prev(Gas1,CO10(Gas1)CO)CO1(Drift

kPa)prev(Gas2,CO10(Gas2)CO)CO2(Drift

Measurement

where:

(Gas1,prev),

pCO

(Gas2,prev)

E(CO

,Gas1), ,Gas2)

,Gas1,prev)

= Partial pressure of CO

Gas 1 and Gas 2, respectively

= Potential of the pCO

Gas 1 and Gas 2, respectively

= Potential of the pCO

from the previous measurement on

electrode from a measurement on

electrode from the previous

measurement on Gas 1

Sens(pCO

,prev)

= Relative sensitivity of the pCO

electrode from the

previous 2-point calibration

Sens(pCO

pCO pCO

(Gas1),

(Gas2)

,theo)

= Theoretical sensitivity (absolute) of the pCO

= Partial pressure of CO

at 37

in Gas 1 and in Gas 2, respectively

The default drift tolerances set by Radopmeter are as follows:

• for Drift 1 are ± 0.33 kPa (2.5 mmHg)

• for Drift 2 are ± 0.67 kPa (5.0 mmHg)

The pCO

=−ppCO (sample, upd30) CO (sample, upd1

predict

value for a sample is calculated from the following equations:

−

pip

2 2

CO (sample,upd6) CO (sample, upd30 CO (sample, upd18

2 2 2

CO (sample, upd6 CO (sample, upd30) CO (sample,upd18)

pp p

22 2

+−×

)

10)gas(CO)updsample,(CO

×=

×−

)

))

electrode

Gas1)E(COupdi)sample,E(CO

theo),COSens(prev),COSens(

]

Continued on next page

2-27

2. Electrodes ABL700 Series Reference Manual

×−+×−

pCO2 Electrode, Continued

Measurement (continued)

where:

pCO

(sample,upd.i) =

uncorrected pCO

from E(CO

sample,upd.i) = potential of the pCO

E(CO

value in the sample calculated

sample,updi) for updating number “i”.

number i with a measurement on the sample.

,Gas1) = potential of the pCO

E(CO

on Gas 1.

Sens(CO

,prev) = relative sensitivity of the pCO

determined from the last calibration on Gas 1 and Gas 2.

Sens(CO

pCO

,theo) = theoretical sensitivity of the pCO

(Gas 1) =

mV) at 37

partial pressure of CO

last calibration.

δ =

difference between pCO

and last updatings.

predict = extrapolated value for pCO

For δ < 1.33 kPa, pCO2(sample) = pCO

(sample,upd30)

For 1.33 kPa < δ < 2.66 kPa

electrode from updating

electrode from a measurement

electrode

electrode (= 61.5

in Gas 1 known from the

(sample) from the first

(.) (..)

CO (sample)

For δ ≥ 2.66 kPa, pCO

is measured in the following syringe and capillary modes:

pCO

predict CO (sample, upd30)

(sample) = predict.

133 266

133

Analyzer Syringe Modes Capillary Modes

ABL735/725/715

195 µL, 95 µL

195 µL, 95 µL, 55 µL

85 µL, Expired air

ABL730/720/710

ABL705

85 µL, Expired air 85 µL, 55 µL

165 µL, 95 µL

165 µL, 95 µL, 55 µL

85 µL, Expired air

ABL700

85 µL, Expired air 55 µL

Continued on next page

2-28

ABL700 Series Reference Manual 2. Electrodes

pCO2 Electrode, Continued

Corrections Blood Samples

The pCO

the reference method using the following equations:

pCO

and

measured on a sample is then corrected for systematic deviations from

(sample,corr) = A

× pCO

+ A

× pCO

(sample)3 + A

(sample) + A

× pCO

(sample)2 +

× (B − pH2O) Equation A

(sample,corr) = B

pCO

× pCO

(sample) + B

Equation B

where: pCO

(sample) = uncorrected value of pCO

in the sample.

B = barometric pressure during the measurement

NOTE: The 195

Series analyzers which do not have it. It is designated as "195

O = partial pressure of saturated water vapor (6.2571 kPa)

= instrument-dependent correction factor

= instrument-dependent interception constant

L is used as the reference measuring mode for those ABL700

L (ref.)" in the

correction tables.

ABL735/725/715 – Syringe mode:

1(95 µL)

0(95 µL)

-0.0000002 0.0051 1.1126 -0.003573 0.992 0.0089

Equation A is used to correct pCO2 value measured on a sample in 195 µL and 85 µL modes. For the 95 µL mode, the measured pCO The obtained result is then used in Equation B to obtain the corrected pCO

value is first corrected using Equation A.

value.

ABL735/725/715 – Capillary mode:

-0.0000002 0.0051 1.1126 -0.003573 1.0937

Equation A is used to correct pCO2 value measured on a sample in 195 µL and 95 µL modes. For the 55 µL mode, the measured pCO The obtained result is then used in Equation B to obtain the corrected pCO

1(55 µL)

0(55 µL)

−0.1463

value is first corrected using Equation A.

value.

Continued on next page

2-29

2. Electrodes ABL700 Series Reference Manual

pCO2 Electrode, Continued

Corrections – Blood Samples (continued)

ABL730/720/710 – Syringe mode:

-0.0000002 0.0051 1.1126

−0.00356

For the 85 µL mode, Equation A is used to correct the pCO

value measured on the sample.

ABL730/720/710 – Capillary mode:

1(55

µL)

0(55 µL)

1(85 µL)

0(85

µL)

-0.0000002 0.0051 1.1126 -0.003573 1.0937 -0.1463 0.997 0.0743

For the 55 and 85 µL mode, the measured pCO The obtained result is then used in Equation B to obtain the corrected pCO

value is first corrected using Equation A.

value.

ABL705 – Syringe mode:

-0.0000002 0.0051 1.1126

Equation A is used to correct pCO2 value measured on a sample in 165 µL and 85 µL modes. For the 95 µL mode, the measured pCO The obtained result is then used in Equation B to obtain the corrected pCO

−0.003573

value is first corrected using Equation A.

1(95 µL)

0(95 µL)

0.992 0.0089

value.

ABL705 – Capillary mode:

-0.0000002 0.0051 1.1126

−0.003573

1(55 µL)

1.0872

0(55 µL)

−0.0924

Equation A is used to correct pCO2 value measured on a sample in 165 µL and 95 µL modes. For the 55 µL mode, the measured pCO The obtained result is then used in Equation B to obtain the corrected pCO

value is first corrected using Equation A.

value.

ABL700 – Syringe mode:

-0.0000002 0.0051 1.1126

For the 85 µL mode, Equation A is used to correct the pCO

−0.003573

value measured on the sample.

ABL700 – Capillary mode:

-0.0000002 0.0051 1.1126

For the 55 µL mode, the measured pCO obtained result is then used in Equation B to obtain the corrected pCO

value is first corrected using Equation A. The

−0.003573

1(55 µL)

1.0872

value.

0(55 µL)

−0.0924

Continued on next page

2-30

ABL700 Series Reference Manual 2. Electrodes

×+×

pCO2 Electrode, Continued

Corrections Expired Air Samples

The pCO

from the reference method using the following equation:

where:

pCO2(sample) = uncorrected pCO

0,Gas

1,Gas

B =

measured from the sample is then corrected for systematic deviations

pBpp −

2Gas1,2Gas0,2

value of a gas sample

1.0196 (instrument dependent correction factor)

−0.00106 (instrument-dependent correction cut-off)

barometric pressure during the measurement

)OH(A(sample)COAcorr)(sample,CO

Stability Criteria

O =

6.2751 kPa (partial pressure of saturated water vapour)

The following stability criterion must be met to obtain a stable electrode response during calibration:

pp − ≤ pCO

upd.i)(sample,OCupd.last)(sample,OC

(limit)

This criterion is valid for calibrations using Gas 1 and Gas 2 where:

Parameter pCO2 value from the last updating number...

pCO

(CalGas,upd.last) 92 62

ABL7x5 ABL7x0

pCO2(CalGas,upd.i) 86 or 87 56 or 57

(the relationship must be fulfilled for at least one of the updating numbers)

pCO

(limit) value for the stability criterion is 0.40 kPa/3.0 mmHg.

Continued on next page

2-31

2. Electrodes ABL700 Series Reference Manual

−

pCO2 Electrode, Continued

Stability Criteria (continued)

The following stability criteria must be met to obtain a stable electrode response during measurement:

δ=

For δ

pp −

upd.i)(sample,OC)upd.30(sample,OC

Criterion

a. ≤1.33 kPa

b. >1.33 kPa

1.0

≤−

−

)upd.16(sample,OCupd.30)(sample,OC

)1upd.(sample,OC)upd.16(sample,OC

≤− pp

5.0

For b):

if the following criteria are fulfilled, then no result is reported:

−

)upd.16(sample,OCupd.30)(sample,OC

0.1

−<

)1upd.(sample,OC)upd.16(sample,OC

)upd.16(sample,OCupd.30)(sample,OC

5.0

≥

)1upd.(sample,OC)upd.16(sample,OC

Expired air samples:

Measurement on an expired air sample is accepted if the following criterion is fulfilled:

⏐pCO

(sample,upd.30) − pCO2 (sample,upd.24)⏐≤0.40 kPa (3.0 mmHg)

40.0)upd.16(sample,OCupd.30)(sample,OC

2-32

⏐pCO Error message "Measurement unstable" (= pCO

(sample,upd.30) − pCO2 (sample,upd.24)⏐≤0.04 × pCO

response fault during electrode

(sample,upd.30).

monitoring in Expired air mode) is displayed if the stability criterion is not fulfilled.

ABL700 Series Reference Manual 2. Electrodes

pO2 Electrode

Basic Description

The pO

anode, platinum cathode and Ag/AgCl reference band, all protected by an electrode jacket which is filled with electrolyte solution. At the tip of the electrode jacket an oxygen-permeable membrane protects the Pt cathode from protein contamination and is covered on the inner side with Pt-black.

electrode (E799) is an amperometric electrode which consists of a silver

The electrode chain is polarized with constant voltage of -630 mV.

Oxygen from the sample diffuses across the membrane into the electrolyte and is reduced on the

g anode

cathode (electrons are consumed) according to the following

gCl reference band

Electrolyte

equation:

+ 4H+ + 4e

2 +

The H

ions come from the

−

→ 2H

electrolyte solution.

This represents the complete

Pt cathode

Membrane

reduction of O however is only partially reduced according to the following

. Some of the O2

equation:

+ 2H+ + 2e

−

→ H

2O2

In the presence of Pt- black, H2O2 produced by the incomplete reduction of O2 at the cathode is immediately decomposed:

2O2

→ 2H

O + O2

This oxygen is then also reduced at the cathode. The reduction of oxygen produces a flow of electrons (an electrical current) the size of this current, I, proportional to the amount of oxygen and measured by the amperemeter:

I = Sens(pO

) × pO2 + I

where:

Sens(pO pO

= Zero current i.e. the current flowing through the circuit when

)= Sensitivity of the pO

= Partial pressure of O2 in the sample

= 0 kPa (mmH

electrode

To complete the electrical circuit, an oxidation reaction where electrons are released is necessary. This reaction which occurs at the silver anode is the conversion of Ag to Ag

Ag → Ag

+ e

−

In order to maintain a charge balance between the anode and cathode, 4 atoms of Ag need to be oxidized for one molecule of O

to be reduced.

Continued on next page

2-33

2. Electrodes ABL700 Series Reference Manual

[

−×=

[

−×=

pO2 Electrode, Continued

Basic Description

(continued)

Sensitivity

The Ag+ ions are released into the electrolyte solution where they react with the

−

ions present, producing AgCl which is insoluble and forms a layer on the silver

Cl rod:

Ag+ + Cl

−

→ AgCl

Not all Ag+ ions can be removed from the solution. Some reach the cathode where they are converted back to Ag and form a deposit of silver. This deposit must be periodically removed with the brush provided in the electrode box.

The pO

electrode is calibrated on two gases with known O2 content.

Gas 1 contains 19.76 % O

and Gas 2 contains 0.0 % O2.

The exact composition of the calibration gases is contained in their bar codes.

The sensitivity of the pO

electrode, Sens(pO

)OSens(

), is calculated as follows:

−

gas2),I(Ogas1),I(O

(gas2)O(gas1)O

2 2

pA/kPa

where:

,gas1)

I(O

pO pO

,gas2)

(gas1)

(gas2)

= Current recorded at the pO = Current recorded at the pO

= Partial pressure of O

= Partial Pressure of O

electrode from a measurement on Gas 1

electrode from a measurement on Gas 2

in Gas 1

in Gas 2

The partial pressures of O

in the gas mixtures Gas 1 and Gas 2 are calculated from

the following equation:

]

pBFp

kPaOH)gas1()gas1(O)gas1(O

222

pBFp

222

]

kPaOH(gas2))(gas2O)(gas2O

where:

FO FO

(gas1),

(gas2)

= Fraction of O

in Gas 1 or Gas 2, respectively

B(gas1), B(gas1)

pHO

= Pressure inside the measuring chamber during a measurement

on Gas 1 or Gas 2, respectively

= Water vapor pressure = 6.2571 kPa at 37

The sensitivity of the pO

electrode should fall between 5 - 40 pA/mmHg or 37.5 -

300 pA/kPa.

Continued on next page

2-34

ABL700 Series Reference Manual 2. Electrodes

−

pO2 Electrode, Continued

Zero Point

The zero point of the pO2 electrode is the electrode current at pO

calculated from the current measured at the electrode with Gas 2 (0 % O sensitivity:

I(O , gas2)

Zero point O

(p ) =

Sens( O , prev)

where:

,gas2)

I(O

= Current recorded at the pO

electrode from measurement on

Gas 2, see zero point current below

Sens(pO

,prev)

= Sensitivity of the pO

electrode measured at the previous 2-

point calibration

The zero point value of the pO

electrode should be less than 6.0 mmHg or 0.80 kPa.

kPa

=0. It is

), and the

Drift

The zero point current is the current measured at the pO

electrode with Gas 2 in

the measuring chamber. When the measurement on Gas 2 begins, a relatively high current is recorded due to residual O

from the rinse solution in the measuring

chamber. This current falls exponentially with time while Gas 2 is present in the measuring chamber.

Forty seconds into the measurement the

Current (pA)

current reaches a steady state which is then considered as the zero point current.

Time (secs)

Drift 1 is a measurement of the difference between two consecutive measurements on Gas 1, and is calculated from the following equation:

I(O gas1 I(O gas2, prev

,) , )

Drift 1( O

)

22)

Sens( O prev

Ogas1 kPa

()=

− p

Drift 2 reflects the change in sensitivity between 2-point calibrations and is calculated from the following equation:

I(O gas2 I(O gas2,prev

,) , )

Drift 2( O

22)

)

Sens( O prev

Ogas2 kPa

()=

− p

where:

,gas1),

I(O I(O

,gas2)

= Current recorded at the pO

on Gas 1 and Gas 2, respectively

electrode from a measurement

,gas2,prev)

I(O

= Current recorded at the pO

electrode from the previous

measurement on Gas 2

Continued on next page

2-35

2. Electrodes ABL700 Series Reference Manual

×−+

pO2 Electrode, Continued

Drift (continued)

Measurement

Sens(pO

,prev)

= Sensitivity of the pO

electrode from the previous 2-point

calibration

(gas1),

pO pO

(gas2)

= Partial pressure of O

in Gas 1 and Gas 2, respectively

The default drift tolerances set by Radiometer are ± 0.80 kPa (6.0 mmHg) for Drift 1 and Drift 2. The Drift tolerances can, however, be user-defined in the Setup program.

The pO

value for a sample is calculated from the following equations:

updi)(sample,O ×

Constant K

describes the gas/liquid relationship for the electrode.

This constant is defined as:

⎛

K 1+ 0 5 8370 21 712

=−+ +

=−ppO (sample, upd30) O (sample, upd1

predict

⎜

.. .

⎝

Sens( O

3.66294

where:

,sample,updi) = Current recorded at the pO

I(O

number i with a measurement on the sample.

,gas2,prev) = Current recorded at the pO

I(O

previous measurement on Gas 2.

Sens(pO

) = Relative sensitivity of the pO

from the last calibration on Gas 1 and Gas 2.

δ =

Difference between pO

updatings.

predict = Extrapolated value for pO

For δ < 2.66 kPa,

(sample) = pO

(sample, upd.30)

−

)OSens(

⎞

)

⎟ ⎠

)

()

ppp

−×

22˜2

ppp

×−+

electrode from updating

electrode from the

electrode determined

(sample) from the first and last

)prevgas2,,I(Oupd.i)sample,,I(O

)18upd.sample,(O)upd.30sample,(O)upd.6sample,(O

22˜2

)18upd.sample,(O2)30upd.sample,(O)upd.6sample,(O

For

2.66 kPa < δ < 5.32 kPa

266

×−(.) (.

Continued on next page

)

δ≥5.32 kPa

For

O(sample)

(sample) = predict

predict O (sample, upd30)

266 532

2-36

ABL700 Series Reference Manual 2. Electrodes

(

pO2 Electrode, Continued

Corrections Blood Samples

The pO

from the reference method using the following equation:

where:

and

k k

measured from the sample is then corrected for systematic deviations

O (sample, corr)

= e

× pO

(sample, v1) + e

dd ee e

−+ −× +× +×

11223 4

4 pp

= 0.02614 (correction constant)

= 0.02107 (correction constant)

O (sample, v1) O (sample, v1)

2 2

(sample)O

2122

)398.100()((sample)Ov1)(sample,O

Bekkpp

−××−+=

Equation A

Equation B

)

is measured in the following syringe and capillary modes:

= −0.00281(correction constant)

Analyzer Syringe Modes Capillary Modes

ABL735/725/715

195 µL, 95 µL

195 µL, 95 µL, 55 µL

85 µL, Expired air

ABL730/720/710

ABL705

85 µL, Expired air 85 µL, 55 µL

165 µL, 95 µL

165 µL, 95 µL, 55 µL

85 µL, Expired air

ABL700

85 µL, Expired air 55 µL

NOTE: The 195

L is used as the reference measuring mode for those ABL700 Series analyzers which do not have it. It is designated as "195 correction tables.

L (ref.)" in the

Continued on next page

2-37

2. Electrodes ABL700 Series Reference Manual

pO2 Electrode, Continued

Corrections Blood Samples (continued)

Constant ABL735/725/715 - Syringe mode

195 µL 95 µL 85 µL

−2.303 −2.303 −2.303

Equations above are used to correct pO

5.96942 5.96942 5.96942

0.83281 0.83281 0.83281

−6.0731 −6.0731 −6.0731

1.30565 1.30565 1.30565

value measured on a sample

ABL735/725/715 - Capillary mode

Equations above are used to correct pO µL and 95 µL modes. For the 55 µL mode, the measured pO corrected using the equations and the constants for the 195 µL mode. The

obtained result is then used in Equations A and B, together with the

constants for 55 µL mode to obtain the corrected pO

195 µL 95 µL 55 µL

−2.303 −2.303 −2.13930

5.96942 5.96942 6.11891

0.83281 0.83281

−0.16485

−6.0731 −6.0731 −5.54016

1.30565 1.30565 1.11462

value measured on a sample in 195

value is first

value for this mode.

Constant ABL730/720/710 - Syringe mode

2-38

Equations above are used to correct pO

µL

−2.303

5.96942

0.83281

−6.0731

1.30565

value measured on a sample.

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

pO2 Electrode, Continued

Corrections Blood Samples (continued)

Constant ABL730/720/710 - Capillary mode

195 µL (ref.) 85 µL 55 µL

−2.303 −2.303 −2.13930

5.96942 5.96942 6.11891

0.83281 0.83281

−0.16485

−6.0731 −6.0731 −5.54016

1.30565 1.30565 1.11462

Equations are used to correct pO2 value measured on a sample in 85 µL mode. For the 55 µL mode, the measured pO the 195 µL mode. The obtained result is then used in Equations A and B as pO together with the constants for 55 µL mode to obtain the corrected pO

value is first corrected using the equations and the constants for

(Sample,v1)

value for this mode

Correction ABL705 - Syringe modes

Equations are used to correct pO2 value measured on a sample in 165 µL, 95 µL and 85 µL

modes

195 µL (ref.) 165 µL 95 µL 85 µL

−2.303 −2.303 −2.303 −2.303

5.96942 5.96942 5.96942 5.96942

0.83281 0.83281 0.83281 0.83281

−6.0731 −6.0731 −6.0731 −6.0731

1.30565 1.30565 1.30565 1.30565

Correction ABL705 - Capillary modes

Equations are used to correct pO2 value measured on a sample in 165 µL and 95 µL modes. For the 55 µL mode, the measured pO constants for the 195 µL mode. The obtained result is then used in Equations A and B as pO

(Sample, v1) together with the constants for 55 µL mode to obtain the corrected pO

value for this mode

195 µL (ref.) 165 µL 95 µL 55 µL

−2.303 −2.303 −2.303 −2.16691

5.96942 5.96942 5.96942 5.17310

0.83281 0.83281 0.83281 0.85016

−6.0731 −6.0731 −6.0731 −5.01679

1.30565 1.30565 1.30565 1.15746

value is first corrected using the equations and the

Continued on next page

2-39

2. Electrodes ABL700 Series Reference Manual

pO2 Electrode, Continued

Corrections Blood Samples (continued)

Constant ABL700 - Syringe mode

µL

−2.303

Equations are used to correct pO

value measured on a sample.

5.96942

0.83281

−6.0731

1.30565

Constant ABL700 - Capillary mode

For the 55 µL mode, the corrected pO calculating pO then used in Equations A and B as pO constants for the 55 µL mode to obtain pO

(sample,corr.)

195 µL 55 µL

−2.303 −2.16691

5.96942 5.17310

0.83281 0.85016

−6.0731 −5.01679

1.30565 1.15746

value in the sample is found by first

for the 195 µL mode. The obtained result is

(sample, v1) together with the

(sample,corr.) for this mode.

2-40

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

−×+×=

pO2 Electrode, Continued

Corrections Expired Air Samples

The pO

from the reference method using the following equation:

where:

pO2(sample) = uncorrected pO

measured from the sample is then corrected for systematic deviations

)OH(A(sample)OAcorr)(sample,O

21202

0,Gas

pBpp

value of a gas sample

= 1.016 (instrument dependent correction factor)

Stability Criteria

B pH

1,Gas

= −0.004 (instrument-dependent correction cut-off)

= barometric pressure during the measurement

= 6.2571 kPa (partial pressure of saturated water vapor)

When measuring on gas samples, the constant K

which describes the gas/liquid

relationship for the electrode, is equal 1.

The following stability criterion must be met to obtain a stable electrode response during

calibration:

pp − ≤ pO

)i.upd(sample,Oupd.last)(sample,O

(limit)

This criterion is valid for 1-point calibrations (Gas 2 contains no oxygen) where:

Parameter pO2 value from the last updating number...

(Gas1,upd.last) 92 62

ABL7x5 ABL7x0

pO2(Gas1,upd.i) 86 or 87 56 or 57

(the relationship must be fulfilled for at least one of the updating numbers)

(limit) value for the stability criterion is 0.80 kPa/6.0 mmHg.

Continued on next page

2-41

2. Electrodes ABL700 Series Reference Manual

−

pO2 Electrode, Continued

Stability Criteria (continued)

The following stability criteria must be met in order to obtain a stable electrode response during

δ=|pO

(sample,upd.30)−pO2(sample,upd.1)|

For δ

measurement:

Criterion

a). ≤ 2.66 kPa

b). > 2.66 kPa

2.0

≤−

−

80.0)upd.16(sample,O(sample)O

≤− pp

)upd.18(sample,O)upd.30(sample,O

upd.6)(sample,O)upd.18(sample,O

For b):

if the following criteria are fulfilled then no result is reported:

−

)upd.18(sample,O)upd.30(sample,O

0.1

−<

upd.6)(sample,O)upd.18(sample,O

)upd.18(sample,O)upd.30(sample,O

6.0

≥

upd.6)(sample,O)upd.18(sample,O

Expired air samples

Measurement on an expired air sample is accepted if the following criterion is fulfilled:

⏐pO

(sample,upd.30) − pO2 (sample,upd.24)⏐≤0.80 kPa/6.0 mmHg,

6.0

(sample,upd30) − pO2 (sample,upd.24)⏐≤0.05 × pO

⏐pO

Error message "Measurement unstable" (= pO

response fault during electrode

(sample,upd.30).

monitoring in Expired air mode) is displayed if the stability criterion is not fulfilled.

2-42

ABL700 Series Reference Manual 2. Electrodes

Electrolyte Electrodes

Basic Description

Electrolyte

Ion-sensitive membrane

Cellophane membrane

The K electrode (E722) is an ionselective electrode whose sensing element is a PVC membrane containing a potassium-neutral ion carrier. The ionsensitive membrane is covered with a cellophane membrane in order to protect it from the samples.

The electrolyte has a constant and known concentration of potassium ions. When a sample is brought in contact with the electrode, a potential develops across the PVC and cellophane membranes. The potential depends on the difference between the potassium (more precisely, activity) in the

electrolyte and the sample. If the cK

in both solutions is the same, the potential across the electrode tip will be 0 V.

The Na electrode (E755) is an ion-

Electrolyte

Nasicon pin

selective electrode whose sensing element is a Na is contained in the tip of the jacket.

The electrolyte has a constant and known concentration of sodium ions. When a sample is brought in contact

-sensitive ceramic pin

with the electrode, a potential develops across the ceramic pin. The potential depends on the difference between the sodium (more precisely, activity) in the

electrolyte and the sample. If the cNa

Cellophane membrane

in both solutions is the same, the potential across the electrode tip will be 0 V.

Continued on next page

2-43

2. Electrodes ABL700 Series Reference Manual

Electrolyte Electrodes, Continued

Basic Description (continued)

Electrolyte

Ion-sensitive membrane

Cellophane membrane

The Ca electrode (E733) is an ionselective electrode whose sensing element is a PVC membrane containing a calcium-neutral ion carrier. The ionsensitive membrane is covered with a cellophane membrane in order to protect it from the samples.

The electrolyte has a constant and known concentration of calcium ions. When a sample is brought in contact with the electrode, a potential develops across the PVC and cellophane membranes. The potential depends on the difference between the calcium (more precisely, activity) in the

electrolyte and the sample. If the cCa

in both solutions is the same, the potential across the electrode tip will be 0 V.

Electrolyte

Ion-sensitive membrane

Cellophane membrane

The Cl electrode (E744) is an ionselective electrode whose sensing element is a PVC membrane containing a chloride ion carrier. The ion-sensitive membrane is covered with a cellophane membrane in order to protect it from the samples.

The electrolyte has a constant and known concentration of chloride ions. When a sample is brought in contact with the electrode, a potential develops across the PVC and cellophane membranes. The potential depends on the difference between the chloride (more precisely, activity) in the

electrolyte and the sample. If the cCl

−

in both solutions is the same, the potential across the electrode tip will be 0 V.

Continued on next page

2-44

ABL700 Series Reference Manual 2. Electrodes

(

Electrolyte Electrodes, Continued

Electrode Chain Potential

The total potential across the electrode chain is a sum of the potential differences at each of the elements in the chain, all but one of which is known and constant. This is outlined in the following table.

Element Potential Symbol

Nernst Equation

Ag/AgCl electrode /electrolyte solution. (Reference electrode)

Membrane junction between the electrolyte solution in the

Known and constant when the Ag/AgCl wire is immersed in the electrolyte solution.

Known and constant, independent of sample composition.

ref

reference electrode and the sample.

Ion-sensitive membrane (or pin) junction separating the

Unknown, dependent on sample

composition.

Sample

sample and the electrode.

Ag/AgCl electrode/inner buffer solution. (Electrolyte electrode)

Known and constant when the Ag/AgCl wire is immersed in the electrolyte solution.

Total potential. Measured by the voltmeter. E

tot

The unknown potential difference across the ion-sensitive membrane or pin is then the difference between the measured total potential and the sum of the known potentials:

EEEEE

=m−++ V

Sample tot ref MJ E

)

The potential difference at the membrane (or pin) in the electrolyte electrodes can be expressed by the Nernst equation:

23R

Sample 0 ion

log mV=+ ×

where:

= standard electrode potential

R =

T n

= absolute temperature (310.15 K at 37

F =

= activity of the specific ion

ion

gas constant (8.3143 J×K

charge on the ion (n = 1 for K

Faraday constant (96487 Cmol

−1

mol−1)

and Na

−1

)

, n = −1 for Cl

−

, n = 2 for Ca2+)

Continued on next page

2-45

2. Electrodes ABL700 Series Reference Manual

Electrolyte Electrodes, Continued

Calibration

The electrolyte electrodes are calibrated by determining the status and sensitivity from 1-point and 2-point calibrations respectively. Performance of the electrode from calibration to calibration is monitored by measuring the drift.

A 1-point calibration is performed using the calibration solution S1720 with the following nominal electrolyte concentrations:

cK cNa cCa cCl

4.0 mmol/L

145 mmol/L

1.25 mmol/L

−

102 mmol/L

The precise concentration of each electrolyte ion is contained in the solution’s bar code.

A 2-point calibration is performed using the calibration solutions S1720 given above and S1730. Calibration Solution S1730 has the following nominal electrolyte concentrations:

cK cNa cCa cCl

40.0 mmol/L

20.0 mmol/L

5.0 mmol/L

−

50.0 mmol/L

Sensitivity

The precise concentration of each electrolyte ion is contained in the solution’s bar codes.

The sensitivity of the electrolyte electrodes is calculated from the following equations:

K electrode

Sens(K)

E(K,Cal1) E(K,Cal2)

61.5 log

−

K(Cal1)

K(Cal2

c )

(fraction)

Na electrode

Sens(Na)

E(Na,Cal1) E(Na, Cal2)

61.5 log

−

Na (Cal1)

N(Cal2

ca )

(fraction)

Ca electrode

Sens(Ca)

E(Ca,Cal1) E(Ca, Cal2)

30 log

×.

−

Ca (Cal1)

Ca (Cal2

(fraction)

)

2-46

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

Electrolyte Electrodes, Continued

Sensitivity (continued)

Cl electrode

−

Cl (Cal1)

−

Cl (Cal2

c )

(fraction)=

Sens(Cl)

E(Cl,Cal1) E(Cl, Cal2)

-61.5 log

where:

E(K/Na/Ca/Cl,Cal1) = Potential of the respective electrolyte electrode

chain from a calibration on Cal 1 solution

E(K/Na/Ca/Cl,Cal2) = Potential of the respective electrolyte electrode

chain from a calibrration on Cal 2 solution

Status

61.5 = Theoretical sensitivity of the K and Na electrodes at

30.75 = Theoretical sensitivity of the Ca electrode at 37

−61.5

/cNa+/cCa2+/cCl

= Theoretical sensitivity of the Cl electrode at 37

−

= Specified concentration of the respective electrolyte

(Cal1)

/cNa+/cCa2+/cCl

−

= Specified concentration of the respective electrolyte

(Cal2)

in Cal 1 solution

in Cal 2 solution

The sensitivity limits of the electrolyte electrodes are as follows:

Electrode Sensitivity Limits

K 92 - 105 %

Na 90 - 105 %

Ca 90 - 105 %

Cl 85 - 105 %

The status of each of the electrolyte electrode is calculated from the following equations:

K electrode

E(K,Cal1) E (K,Cal1)

−

Status(K)

61.5

K(Cal1)

K(Cal1,nom)

mmol / L

Na electrode

E(Na,Cal1) E (Na,Cal1)

−

Status(Na)

61.5

N(Cal1)

N(Cal1,nom)

mmol / L

Continued on next page

2-47

2. Electrodes ABL700 Series Reference Manual

Electrolyte Electrodes, Continued

Status (continued)

Ca electrode

Status(Ca)

E(Ca,Cal1) E (Ca, Cal1)

−

30.75

C(Cal1)

C(Cal1,nom)

mmol / L

Cl electrode

E(Cl,Cal1) E (Cl,Cal1)

−

Status(Cl)

-61.5

Cl (Cal1)

−

Cl (Cal1, nom)

−

mmol / L

where:

E(K/Na/Ca/Cl,Cal1) = Potential of the respective electrolyte electrode

chain from a calibration on Cal 1 solution

(K/Na/Ca/Cl,Cal1) = Standard potential of the respective electrolyte

electrode chain with the following nominal electrolyte concentrations:

cK cNa cCa cCl

= 4.0 mmol/L

= 145.0 mmol/L

= 1.25 mmol/L

−

= 102.0 mmol/L

(These concentrations correspond to the approximate concentrations of each of the electrolytes in Cal 1 solution).

/cNa+/cCa2+/cCl

(Cal1,nom)

−

= Nominal concentration of the respective electrolyte

ion in Cal 1 solution (see above)

The status limits of the electrolyte electrodes are as follows:

Electrode Status Limits

K 0.5 - 12 mmol/L

Na 10 - 250 mmol/L

Ca 0.1 - 20 mmol/L

Cl 30 - 900 mmol/L

Continued on next page

2-48

ABL700 Series Reference Manual 2. Electrodes

Electrolyte Electrodes, Continued

Drift

Drift 1 is the difference between two consecutive calibrations on Cal 1 solution and is calculated for each of the electrolyte electrodes.

reflects the change in sensitivity between 2-point calibrations and is

Drift 2 calculated for each of the electrolyte electrodes.

The drift equations are given below.

K electrode

E(K,Cal1) E(K,Cal1, prev)

−

61.5 Sens(K,prev)

Drift 1(K) 10 K Cal1, prev K Cal1 mmol / L

Drift 2(K) 10 K Cal1, prev K (Cal2 mmol / L

=×−

E(K,Cal2)- E(K,Cal1,prev)

61.5 Sens(K,prev)

cc()()

() )

Na electrode

E(Na,Cal1) E(Na,Cal1,pr ev)

−

61.5 Sens(Na,prev)

Drift 1(Na) 10 Na Cal1, prev Na Cal1 mmol / L

Drift 2(Na) 10 Na Cal1, prev Na (Cal2 mmol / L

=×−

E(Na,Cal2)- E(Na,Cal1,prev)

61.5 Sens(Na,prev)

cc()()

() )

Ca electrode

E(Ca,Cal1) E(Ca,Cal1,prev)

−

30 Sens(K, prev)

×.

Drift 1(Ca) 10 Ca Cal1,prev Ca Cal1 mmol / L

Drift 2(Ca) 10 Ca Cal1, prev Ca (Cal2 mmol / L

=×−

E(Ca,Cal2) -E(Ca,Cal1, prev)

30 Sens(Ca, prev)

×.

2+ 2+

()()

() )

Cl electrode

−

prev)Cal1,E(Cl,Cal1)E(Cl,

prev)Sens(Cl,61.5-

prev)Cal1,E(Cl,-Cal2)E(Cl,

prev)Sens(Cl,61.5-

−−

−×= cc

−−

−×= cc

mmol/L)Cal1(Cl)prevCal1,(Cl101(Cl)Drift

mmol/L)(Cal2Cl)prevCal1,(Cl102(Cl)Drift

where:

E(K/Na/Ca/Cl,Cal1), E(K/Na/Ca/Cl,Cal2)

= Potential of the respective electrolyte electrode

chain from a calibration on Cal 1 and Cal2 solution, respectively

E(K/Na/Ca/Cl,Cal1,prev) = Potential of the respective electrolyte electrode

chain from the previous calibration on Cal 1 solution

61.5 = Theoretical sensitivity of the K and Na electrodes at 37

Continued on next page

2-49

2. Electrodes ABL700 Series Reference Manual

Electrolyte Electrodes, Continued

Drift (continued)

30.75 = Theoretical sensitivity of the Ca electrode at 37

−61.5

= Theoretical sensitivity of the Cl electrode at

Sens(K/Na/Ca/Cl,prev) = Sensitivity of the respective electrolyte

electrode from the last 2-point calibration

/cNa+/cCa2+/cCl

rev)

/cNa+/cCa2+/cCl

/cNa+/cCa2+/cCl−(Cal2)

−

(Cal1,p

−

(Cal1),

Concentration of the respective electrolyte in

Cal 1 solution in the previous calibration

Specified concentration of the respective

electrolyte in Cal 1 and Cal2 solution, respectively

NOTE: If Cal 1 solution bottle has not been changed between two consecutive

−

calibrations, the cX(Cal1,prev)

cX(Cal1) = 0, where X is the respective

electrolyte ion.

The default drift tolerances set by Radiometer are as follows:

Electrode Drift 1 Tolerances Drift 2 Tolerances

± 0.2 mmol/L ± 1.5 mmol/L ± 3 mmol/L ± 1 mmol/L ± 0.05 mmol/L ± 0.2 mmol/L ± 2 mmol/L ± 3 mmol/L

Measurement

The electrolyte concentration in a sample is calculated from the following equation:

E(X,sample)- E(X,Cal,prev)

Sens(theo) Sens(X,prev

ccX(sample) X(Cal, prev) 10

=×

× )

where:

E(X,sample) = Potential of the electrolyte electrode chain from a

measurement on the sample.

E(X,Cal,prev) = Potential of the electrolyte electrode chain from the

previous calibration on Cal 1 solution.

(Cal 1) =

Specific (true) concentration of the electrolyte ion in Cal 1 solution.

(theo) = Theoretical sensitivity of the electrolyte electrode.

Sens

Sens(X,prev) = Relative sensitivity of the electrolyte electrode chain from

the last 2-point calibration.

Continued on next page

2-50

ABL700 Series Reference Manual 2. Electrodes

+×=

(

)

Electrolyte Electrodes, Continued

Corrections

The measured electrolyte concentration is then corrected for systematic deviations from the reference method by the following equations:

X(sample)Acorr)X(sample, Acc

Equation A

L)µ(1951L)µ(1950µL195

and

ccX(sample,corr) X(sample)

=× +A

95 L 0 (95 L) (95 L)

µµ µ

Equation B

For the Cl electrode only, Equation A reads as:

L)µ(1950Lµ195

−

HCO0956.0(sample)ClAcorr)(sample,Cl Accc +×−×=

L)µ5(1913

where:

cX(sample) = uncorrected value of the electrolyte ion in the sample

cHCO

−

= bicarbonate concentration of 24.5 mmol/L.

= instrument-dependent correction factor

= instrument-dependent interception constant

Correction ABL735/725/715 - Syringe modes

Na Ca

For the 195 µL mode the measured electrolyte concentration is corrected using Equation A.

For the 95 µL mode, the measured electrolyte concentration is first corrected using Equation A and the constants for the 195 µL mode. cX(sample,corr) from this equation is then used in Equation B as cX(sample) to obtain the final corrected electrolyte concentration in the sample for this mode.

Electrolyte Ion

−

195

µL 95 µL

0.984 1.0228

0.9942 0.9750

1.00415 1.0174

1.247 0.991

−0.060 −0.0268

195 µL

5.5365

0.0155

0.887

obtained

−2.6020

−0.023

−30.756

Continued on next page

2-51

2. Electrodes ABL700 Series Reference Manual

Electrolyte Electrodes, Continued

Corrections (continued)

Correction ABL735/725/715 - Capillary modes

Na Ca

For the 195 µL mode the measured electrolyte concentration is corrected using Equation A.

Electrolyte Ion

−

195

µL 95 µL

0.984 1.059

0.9942 0.999

1.00415 1.097

1.247 0.991

−0.060 −0.179

−2.6020

3.190

−0.0230 −0.070

195 µL

0.887

obtained

−30.756

Correction ABL705 - Syringe modes

Electrolyte

195

µL 165 µL 95 µL

Ion

−

For the 165 µL mode the measured electrolyte concentration is corrected using Equation A.

For the 95 µL mode, the measured electrolyte concentration is first corrected using Equation A and the constants for the 195 µL mode. cX(sample,corr) this equation is then used in Equation B as cX(sample) to obtain the final corrected electrolyte concentration in the sample for this mode.

0.984 0.984 1.0228

0.9942 0.9942 0.975

1.00415 1.00415 1.0174

1.247 1.247 0.991

−0.060 −0.060 −0.0268

−2.6020 −2.6020

−0.0230 −0.0230

−30.756 −30.756

195 µL

5.5365

0.0155

0.887

obtained from

2-52

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

Electrolyte Electrodes, Continued

Corrections (continued)

Correction ABL705 - Capillary modes

Electrolyte

195

µL 165 µL 95 µL

Ion

−

0.984 0.984 1.059

0.9942 0.9942 0.999

1.00415 1.00415 1.097

1.247 1.247 0.991

−0.060 −0.060 −0.179

−2.6020 −2.6020

−0.0230 −0.0230 −0.070

−30.756 −30.756

3.190

0.887

Stability Criteria

For the 165 µL mode the measured electrolyte concentration is corrected using Equation A.

For the 95 µL mode, the measured electrolyte concentration is first corrected using Equation A and the constants for the 195 µL mode. cX(sample,corr)

obtained from

195 µL

this equation is then used in Equation B as cX(sample) to obtain the final corrected

electrolyte concentration in the sample for this mode

See Chapter 5, Performance Specifications for more information on reference

methods.

The following stability criterion must be met to obtain a stable electrode response during calibration:

upd.last)X(sample,K)upd.iX(sample,upd.last)X(sample, ccc ×≤−

This criterion is valid for calibrations using Cal 1 and Cal 2 solutions where:

cX(Cal,upd.last) = Concentration of the electrolyte ion from the last updating

when measuring on calibration solution. (The last updating is number 30).

cX(Cal,upd.i) = Concentration of the electrolyte ion for a given updating

when measuring on calibration solution. (The relationship must be fulfilled for at least one of the updating numbers 18 or 19).

Continued on next page

2-53

2. Electrodes ABL700 Series Reference Manual

Electrolyte Electrodes, Continued

Stability Criteria (continued)

where (continued):

K = Constant for the stability criterion.

Electrolyte Ion Cal1 solution Cal2 solution

−

0.01 0.01

0.01 0.02

0.02 0.02

0.022 0.022

The following stability criterion must be met to obtain a stable electrode response during measurement:

≤−

)upd.iX(sample,upd.last)X(sample,

()

X(Rinse)X(Rinse)upd.last)X(sample,K

ccc

+−×

where:

cX(sample,upd.last) = Concentration of the electrolyte ion from the median

of the last 5 updatings (for Ca

: 3 last updatings) when measuring on a sample. The last updating number is 30 (or 10 for some micromodes).

cX(sample,upd.i) = Concentration of the electrolyte ion for a given

updating when measuring on a sample. (The relationship must be fulfilled for at least one of the updating numbers shown below).

−

2-54

22 22 26 22

23 23 27 23

In some micromodes, substract 20 from number

above.

K Constant for the stability criterion; it equals to:

= 0.012; Na+ = 0.012; Ca2+ = 0.022; Cl− = 0.012

Rinse

Constant that includes the concentration of the electrolyte ion in rinse solution:

= 4.0; Na+ = 130.0; Ca2+ = 1.25; Cl− = 137.7

ABL700 Series Reference Manual 2. Electrodes

Metabolite Electrodes

Basic Description

g cathode gCl reference band

Electrolyte

The glucose electrode (E7066) and the lactate electrode (E7077) have similar construction described below.

The electrode consists of a silver cathode and a platinum anode. The electrode is protected by an electrode jacket filled with electrolyte solution and a multi-layer membrane mounted at the tip.

The membrane consisting of three layers:

Multi-layer membrane

1. outer membrane layer permeable to glucose.

2. middle enzyme layer.

3. inner membrane layer permeable to

2O2

A polarization voltage of 675 mV is applied to the electrode chain and the current through the chain is measured by an amperemeter.

Glucose or lactate molecules are transported across the outer membrane of the multi-layer membrane.

The enzyme glucose oxidase or lactate oxidase immobilized between the inner

g cathode

gCl reference band

Multi-layer membrane

Electrolyte

and outer membrane layers converts the glucose or lactate according to the following reactions:

glucose + O

lactate + O

for this reaction is supplied by the

outer membrane layer and also by the oxidation of H

The H

→ gluconic acid + H

→ pyruvate + H

at the Pt anode.

2O2

produced by the enzyme

2O2

reaction is transported across the inner membrane to the Pt anode.

Continued on next page

2-55

2. Electrodes ABL700 Series Reference Manual

Metabolite Electrodes, Continued

Basic Description (continued)

Zero Current

O → 2H

+ O2 + 2e

−

When a potential is applied to the electrode chain, the oxidation of H

produces an

2O2

electrical current proportional to the amount of H

, which in turn is directly

2O2

related to the amount of glucose or lactate.

To complete the electrical circuit a reduction reaction (where electrons are consumed) at the cathode converts Ag

(from AgCl) to Ag:

+ e

−

→ Ag

In order to maintain a charge balance between the anode and the cathode, two Ag ions need to be reduced for one molecule of H

to be oxidized.

2O2

The zero current is a small background current measured at the electrode when no glucose or lactate is present in a solution. As the rinse solution contains no glucose or lactate, a baseline representing the zero current, I

as a function of time (I0 =

f(t)), is obtained from continuous measurements on the rinse solution.

(current)

Rinse

xxx

N measurements of I on the rinse solution

I0(t)

mean

Extrapolated base-line

(t)

final

Time

This I0 baseline is obtained as follows:

• At the end of a rinse, with the rinse solution in the measuring chamber, zero

current of the metabolite electrodes is measured periodically (the intervals between these measurements become longer if the analyzer is idle).

• The previous N (N = 8) measurements on the rinse solution – before a calibration or

a sample measurement starts - are used to obtain a baseline representing the time function of I

Continued on next page

2-56

ABL700 Series Reference Manual 2. Electrodes

(

+−××=

Metabolite Electrodes, Continued

Zero Current (continued)

• The baseline is extrapolated throughout the whole electrode calibration or

sample measurement period, and represents the zero current time function.

• The I

baseline is used to determine the sensitivity of the metabolite electrode.

The extrapolated final zero current value at the metabolite electrodes at the last updating (illustrated by the I

baseline) is determined as follows:

)

0meanfinal slope10

pA(mean) IttI(final)I

where:

= Empirical constant dependent on electrode and determined from

tests against the reference method

final

= Time of the last measurement updating on the calibration solution

or sample.

mean

(mean) =

The mean time of the N zero current measurements on the rinse solution:

mean

where t

The zero current at the mean time (t

∑

sec

is the time of the nth measurement on the rinse solution.

mean

n0,

∑

(mean)I

where I

is the zero current at the nth measurement on the rinse

0,n

solution.

slope

= The slope or gradient of the I0 baseline

()

∑

1=n

slope

> 0.0, it is set to 0.0

If I

slope

meann

∑

()

−×−

(mean)IItt

0n0,

()

−

1=n

meann

pA/second

The zero current of the metabolite electrodes should be less than 10000 pA.

Continued on next page

2-57

2. Electrodes ABL700 Series Reference Manual

Metabolite Electrodes, Continued

Sensitivity

The sensitivities of the metabolite electrodes are calculated by measuring the current on Calibration Solution 1 (Cal 1) and then correcting for the zero current using the extrapolated I

baseline.

Cal 1 has a nominal glucose concentration of 10 mmol/L and a nominal lactate concentration of 4 mmol/L. The precise values are batch-individual and contained in the bar codes of the Cal 1 bottles.

The diagram below, together with the table, describes in principle how the sensitivities for the metabolite electrodes are obtained.

Electrode updatings

I(Cal 1,upd.N)

I(Cal 1)

I(Cal 1,upd.2)

xxx

N measurements of I on rinse solution

I(Cal 1,upd.1

Start of Calibration

I0(final)

End of

Calibration

Extrapolated base-line

The current at the metabolite electrodes with Cal 1 in the measuring chamber, I(Cal

1), is measured 30 times at regular intervals. The current at the 15th updating is used to determine sensitivity of the glucose electrode, and the current at the 30 updating is used to determine sensitivity of the lactate electrode.

The current due to the glucose or lactate presence in the sample is then calculated as the difference between the current at the final updating (the 15 and the30

for the lactate electrode) and the zero current at that time point:

for the glucose

− I

I(Cal 1) = I(Cal 1,final)

(final)

The sensitivities of the electrodes are calculated as follows:

2-58

Sens

1)I(Cal

1)X(Cal

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

−

Metabolite Electrodes, Continued

Sensitivity (continued)

Drift

where:

cX(Cal 1) = Actual concentration of glucose/lactate in the Cal 1

solution.

(final) = Extrapolated final zero current value of the metabolite

electrode at the time of the last updating.

I(Cal 1) = electrode current due to presence of glucose/lactate.

The sensitivity limits of the metabolite electrodes are as follows:

Electrode Sensitivity Limits

Glucose 100 - 1800 pA/mM

Lactate 150 - 2000 pA/mM

The drift in the sensitivity of the metabolite electrodes is calculated from the following equations:

(final)Ifinal)1,I(Cal

Drift

c−

1)X(Cal

Sens

where:

I(Cal 1,final) = Current at the final measurement on Cal 1 solution.

Sens = Sensitivity of the glucose/lactate electrode from the

calibration.

cX(Cal 1) = Actual concentration of glucose/lactate in the Cal 1 solution.

(final) = Extrapolated final zero current value of the metabolite

electrode measured at the time of the last updating.

The default drift tolerances set by RADIOMETER for the metabolite electrodes are:

± 0.5 mM for the glucose electrode ± 0.2 mM for the lactate electrode.

Continued on next page

2-59

2. Electrodes ABL700 Series Reference Manual

−

+×=

Metabolite Electrodes, Continued

Measurement

Corrections

The glucose/lactate concentration in a sample is calculated from the following equation:

(final)II(sample)

X(sample)

Sens

where:

I(sample) = Current of the metabolite electrode measured on the

sample.

(final) = Extrapolated final zero current value of the metabolite

electrode at the time of the last sample updating.

Sens = Relative sensitivity of the metabolite electrode.

The measured metabolite concentration is corrected for systematic deviations from the reference method by the following equations:

L195

X(sample)Acorr)X(sample,

Acc +×= Equation A

L)(1951L)(1950

µµ

and

cc Equation B

AX(sample)Acorr)X(sample,

µL)1(95/35µL)0(95/35µL95

where:

cX(sample) = uncorrected measured glucose/lactate concentration from a

sample

instrument-dependent correction factor

instrument-dependent interception constant

Continued on next page

2-60

ABL700 Series Reference Manual 2. Electrodes

Metabolite Electrodes, Continued

Corrections (continued)

Correction ABL735/725/715 - Syringe modes

Metabolite

195

µL 95 µL

cGlu 0.93 1.0040

cLac 0.93 1.0082

cGlu 0.1

−0.0171

cLac 0.0268 0.0017

For the 195 µL mode the measured metabolite concentration is corrected using Equation A.

For the 95 µL mode, the measured metabolite concentration is first corrected using Equation A and the constants for the 195 µL mode. cX(sample,corr) from this equation is then used in Equation B as cX(sample) to obtain the final corrected metabolite concentration in the sample for this mode.

195 µL

obtained

Correction ABL735/725/715 - Capillary modes

cLac

For the 195 µL mode the measured metabolite concentration is corrected using Equation A.

For the 95 µL and 35 µL modes, the measured metabolite concentration is first corrected using Equation A and the constants for the 195 µL mode. The obtained cX(sample,corr) corrected metabolite concentration in the sample for this mode.

Metabolite

cGlu

µL 95 µL 35 µL

195

0.93 1.053 1.1438

0.93 1.044 1.1724

cGlu cLac

is then used in Equation B as cX(sample) to obtain the final

195 µL

0.1 0.014

0.0268

−0.020 −0.0411

−0.0602

Correction ABL705 - Syringe modes

cLac

For the 165 µL mode the measured metabolite concentration is corrected using Equation A.

Metabolite

cGlu

cGlu cLac

µL 165 µL 95 µL

195

0.93 0.896 1.0040

0.93 0.900 1.0082

0.1 0.1576

−0.0171

0.0268 0.0268 0.0017

obtained

195 µL

Continued on next page

2-61

2. Electrodes ABL700 Series Reference Manual

Metabolite Electrodes, Continued

Corrections (continued)

Correction ABL705 - Capillary modes

Metabolite

µL 165 µL 95 µL 35 µL

195

Stability Criteria

cGlu

cLac

For the 165 µL mode the measured metabolite concentration is corrected using Equation A.

For the 95 µL and 35 µL mode, the measured metabolite concentration is first corrected using Equation A and the constants for the 195 µL mode. cX(sample,corr) from this equation is then used in Equation B as cX(sample) to obtain the final corrected metabolite concentration in the sample for this mode.

cGlu cLac

0.93 0.896 1.053 1.1438

0.93 0.900 1.044 1.1724

0.1 0.1576 0.014

0.0268 0.0268

−0.020 −0.0411

195 µL

−0.0602

obtained

See Chapter 5, Performance Characteristics for more information on reference

methods.

The following stability criteria must be met to obtain a stable electrode response during calibration:

I(Cal 1,upd.30)

< S

d,zero

log

− I(Cal 1, upd.21) − 9 × I

d,max

5.9

−

upd.11)1,I(Calupd.1)1,I(Cal

upd.21)1,I(Calupd.11)1,I(Cal

slope

≤ 0

≤

All of the three criteria must be fulfilled for a calibration using Cal 1 solution where:

I(Cal 1,upd.30)

I(Cal 1,upd.21)

= Electrode current at the 30

measurement on Cal 1 solution, respectively.

/21st/11th/1st updating during

2-62

I(Cal 1,upd.11)

I(Cal 1,upd.1)

d,zero

d,max

= Spreading of the zero point current updatings around the

regression line.

If Sens > 400 pA/mM, then = 0.025 × Sens,

otherwise = 10.0.

maxd,

Continued on next page

ABL700 Series Reference Manual 2. Electrodes

−

×−−

Metabolite Electrodes, Continued

Stability Criteria

(continued)

= Should be less than or equal to 50,

and

log

upd.11)1, I(Calupd.1)1, I(Cal

−

upd.21)1, I(Calupd.11)1, I(Cal

should be negative or equal zero.

The following stability criterion must be met to obtain a stable electrode response during measurement:

d,zero

< S

d,max

where:

d,zero

= Spreading of the zero point current updatings around the

regression line.

d,max

If Sens > 400 pA/mM, then S otherwise S

d,max

= 10.0.

= 0.025 × Sens,

d,max

The (glucose or lactate) in the sample is

If the corrected concentration of the metabolite,

cX(sample,corr).

cX(sample,corr) > 1, the following

criteria must be fulfilled:

I9upd.21)1, I(Calupd.30)1, I(Cal

≤

−

slope

200.

≤

)30.(updIupd.30)I(sample,

otherwise

I9upd.21)I(sample,upd.30)I(sample,

×−−

slope

≤

14.0

Sens

where:

I(Cal 1,upd.30)

I(Cal 1,upd.21)

2-63

= Electrode current at the 30th/21st updating during

measurement on sample, respectively.

Continued on next page

2. Electrodes ABL700 Series Reference Manual

Metabolite Electrodes, Continued

Stability Criteria (continued)

If all the criteria below are fulfilled, then the result of the measurement will be marked with an interference error.

upd.23)I(sample,-upd.30)I(sample,

≥

upd.9)I(sample,-upd.16I(sample,

I(sample,upd.16) > I(sample,upd.12)

I(sample,upd.12) > I(sample,upd.9)

cX(sample,corr)> 1.5 mmol/L

where:

I(sample,upd.30) I(sample,upd.23) I(sample,upd.16)

= Electrode current at the 30

updating during measurement on sample, respectively.

/23rd/16th/12th/9th

I(sample,upd.12) I(sample,upd.9)

cX(sample,corr) = Corrected concentration of glucose or lactate in

the sample.

2-64

ABL700 Series Reference Manual 2. Electrodes

References

List of References

List of the references for Chapter 2, Electrodes:

1. Linnet N. pH measurements in theory and practice. 1st ed. Copenhagen:

Radiometer Medical A/S, 1970.

2-65

Introduction

Contents

3. The Optical System

This chapter describes the optical system in the ABL700 Series analyzer, its construction, and the measuring method used.

This chapter contains the following topics.

Measuring Principle ......................................................................................... 3-2

Correcting for Interferences ............................................................................. 3-7

Calibration........................................................................................................ 3-9

Measurement and Corrections.......................................................................... 3-10

References........................................................................................................ 3-13

3. The Optical System ABL700 Series Reference Manual

Measuring Principle

Introduction

The optical system of the ABL700 Series analyzer is designed to measure the following parameters:

Parameter Description

ctHb concentration of total hemoglobin

Optical System

oxygen saturation

FO2Hb fraction of oxyhemoglobin FCOHb fraction of carboxyhemoglobin FHHb fraction of deoxyhemoglobin FMetHb fraction of methemoglobin FHbF fraction of fetal hemoglobin ctBil concentration of total bilirubin (the sum of unconjugated

and conjugated bilirubin) in plasma

NOTE: ctBil can be measured on a whole blood or plasma sample. Plasma samples provide the optimal measurement performance. To obtain optimal accuracy when following a patient trend in ctBil, use the same aspiration mode and the same analyzer.

Hematocrit (Hct) is also available as a derived parameter.

The optical system is based on a 128-wavelength spectrophotometer with a measuring range of 478 - 672 nm. The spectrometer is connected via an optical fiber to a combined hemolyzer and measuring chamber.

Spectrofotometer

Photodiode array

Concave grating

Slit

Optical fiber

Sample out

Hemolyze

Sample in

Cuvette

Lamp unit

Infrared filter

Lens

Continued on next page

3-2

ABL700 Series Reference Manual 3. The Optical System

Measuring Principle, Continued

Optical System

(continued)

The method used in the ABL700 Series analyzer's optical system is visible absorption spectroscopy.

Step Description

The blood sample is transported to the cuvette positioned in the

hemolyzer unit. The temperature of the cuvette is regulated to 37

1 µL of the sample is ultrasonically hemolyzed in the cuvette at a

frequency of about 30 kHz in order to rupture the walls of the red blood cells so that their content is mixed with the blood plasma, giving an optically clear solution. There is no bilirubin in the red blood cells, so after hemolyzation the red blood cell intracellular fluid dilutes the plasma bilirubin. The calculation discussed in

Measurement and Corrections corrects for this dilution.

To eliminate air bubbles in the sample and to enhance hemolyzation, an over-pressure of one atmosphere is maintained throughout hemolyzation and measurement.

Light from a 4 Watt halogen lamp is sent to the cuvette via an infra-

red filter and a biconvex lens.

The voltage across the halogen lamp is regulated by a thermostatted photodiode so that the amount of light sent to the cuvette has a constant intensity.

The light transmitted through the cuvette is guided to the spectrometer via

an optical fiber.

The light passes through a slit that directs it towards a combined

mirror and concave grating.

The grating separates the light into 128 single wavelengths and the

mirror focuses the 128 light signals on a photodiode array.

The photodiode array has 128 diodes or pixels, one for each

wavelength, which convert the monochromatic light signals to currents.

The currents and therefore the intensity of the light signals are

measured at each of the 128 diodes, which form the basis for the absorption spectrum for a particular sample.

The spectrum is sent to the analyzer’s computer, where the

calculations of the oximetry parameter values are made.

Continued on next page

3-3

3. The Optical System ABL700 Series Reference Manual

(

Measuring Principle, Continued

Lambert-Beer’s Law

Absorption spectroscopy is based on Lambert-Beer's law which states that the measured absorbance for a single compound is directly proportional to the concentration of the compound and the length of the light path through the sample [1]:

λλ

ε=××yl

where:

absorbance of compound y at wavelength λ

extinction coefficient of compound y at wavelength λ (a constant, characteristic of the compound)

Absorbance

Total Absorbance

= concentration of compound y in sample

= length of light path

The absorbance (A) of a compound is defined as the logarithm of the ratio of the light intensity before and after transmission through the compound.

In practice it is the logarithm of the ratio of the light intensity transmitted through water to the light intensity transmitted through the compound.

=log

is measured as the

where:

intensity of light transmitted through water (I

intensity of light transmitted through the Cal 1 or Cal 2 solutions)

= intensity of light transmitted through the compound

For samples containing more than one optically active compound, the total absorbance (A

) is the sum of the individual compounds’ absorbance, since

total

absorbance is an additive quantity.

For example, if a sample contains 6 compounds y measured for that sample at wavelength λ

λ λλλλλ

1 11111

A AAAAAA

=+++++

total y y y y y y

12345

λλλλλλ

111 1411

=+++++lc c c c c c

εεεεεε

yy yy yy yy yy yy

11 22 33 4 55 66

is:

, y2, ….y6, the total absorbance

)

If there are Y compounds and measurements are taken at

expression can be written for

at the wavelength λ

total

λλ

total y y

=×

=∑1

n wavelengths, a general

l×

where:

= the individual wavelengths.

Continued on next page

3-4

ABL700 Series Reference Manual 3. The Optical System

Measuring Principle, Continued

Continuous Spectrum

Absorption

can be depicted graphically as a function of wavelength, and if the

total

differences between the wavelengths are small enough, a continuous spectrum is produced.

EXAMPLES:

The figure below shows three spectra; pure O2Hb, pure HHb in a low concentration, a spectrum of 92 % oxygenated hemoglobin obtained by adding the spectra of O

Hb and HHb. The additivity of absorption and the continuity of the

spectra can clearly be seen.

480

O2Hb (9.2 mmol/L)

HHb (0.8 mmol/L)

92 % oxygenated hemoglobin (i.e., 92 % O2Hb + 8 % HHb)

500

520

540

560

580

600

620

640

660

Wavelength/nm

680

Example of the spectrum obtained from unconjugated bilirubin at concentration of 200

µL.

200umol/L Unconjugated B ilir ubin in Plasma

0.1

0.08

0.06

0.04

Absorbance

0.02 0

470 520 570 620 670

The spectrum of conjugated bilirubin is slightly different.

Continued on next page

3-5

3. The Optical System ABL700 Series Reference Manual

Measuring Principle, Continued

Determining Concentrations

Matrix of Constants

In the spectrum taken of a sample, the absorption recorded at each wavelength contains contributions from each of the compounds in the sample. The task then is to determine the magnitude of that contribution and thereby the concentration of each compound in the sample.

The concentrations are determined using the following equation:

128

λλ

∑

y y total

where:

a constant specific to compound y at wavelength

The constants ( ) are determined using Multivariate Data Analysis [2] where

the spectra of the calibration compounds were considered together with the reference values of the calibration compounds. The essential interfering substances were also taken into account.

3-6

ABL700 Series Reference Manual 3. The Optical System

Correcting for Interferences

HbF vs. HbA

Fetal hemoglobin (HbF) does not have the same spectrum as adult hemoglobin (HbA) due to a slight variation in molecular structure. The presence of HbF in a sample will interfere with the result if it is not corrected for.

It is thus important when measuring hemoglobin levels in premature neonates and neonates aged 0 to 3 months, as well as adults suffering from thalassemia, to take into account this difference

[3].

The ABL700 Series analyzer automatically corrects for HbF.

NOTE: Hb types other than HbA and HbF interfere with hemoglobin

measurements and are not compensated for in the ABL700 Series analyzers.

The diagram below shows the transition from fetal hemoglobin to adult hemoglobin

[4].

Deviation of Results

Detecting HbF

Correcting for HbF

This graph is only schematic and cannot be used to determine

FHbF.

If the difference between the two types of hemoglobin is not accounted for in measurements on samples containing HbF, e.g. from premature neonates and neonates aged 0 to 3 months, then a deviation in the measurement will arise.

The deviation is most important for measurements of oxygen saturation ( the fraction of carboxyhemoglobin (

FCOHb), since inaccurate measurements of

) and

these parameters can lead to incorrect diagnostic interpretation of the results, and consequent risk of inappropriate treatment.

The presence of HbF in a sample is detected from the difference spectrum between fetal and adult oxyhemoglobin. From the size of the difference spectrum the

concentration of fetal oxyhemoglobin,

The amount of cO

HbF exceeding a certain level indicates HbF interference. The

HbF, can be measured.

analyzer automatically corrects for this interference by subtracting the difference spectrum of fetal oxyhemoglobin from the measured spectrum. It then makes

further calculations, using

HbF to measure FHbF.

Continued on next page

3-7

3. The Optical System ABL700 Series Reference Manual

Correcting for Interferences, Continued

Most Likely Interfering Substances

Repressing Spectra

Fetal hemoglobin and non-hemoglobin substances present in blood that absorb light within the same wavelength range used to measure the oximetry parameters and bilirubin, will interfere with the true spectra of the blood samples.

The optical system in the ABL700 Series analyzers compensates for the most likely interfering substances by repressing their spectra.

The interference from following substances an ABL700 Series analyzer compensates for when measuring the oximetry parameters:

Intralipids (turbidity)

Sulfhemoglobin, SHb

Repressing the spectra of the likely interfering substances is done in two ways depending on the substance:

• Either the substance is taken account of in the calculation of the matrix of

constants, K (see the section

Measuring Principle in this chapter). This applies

to Intralipids and Sulfhemoglobin,

Residual Spectrum

• Or the substance is detected, and the measured spectrum is corrected

accordingly. This applies to HbF.

A measured spectrum is compared to a model spectrum calculated from the determined concentrations. The difference between the two spectra is then called the residual spectrum. If the difference is too high a warning (Oxi spectrum mismatch) is issued on all the oximetry module parameters

ctHb, sO

, FO

Hb,

FCOHb, FMetHb, FHHb, FHbF and ctBil.

The same action is taken if one of the following conditions exist and defined as one of the parameters

sO2, FO

Hb, FCOHb, FMetHb, FHHb:

FHb

deriv

• ctHb<−0.1mmol/L or ctHb>25mmol/L.

• FHb(deriv)<-2% or FHb(deriv)>102%.

• Negative fraction of SHb<−2% is detected.

• Value of Turbidity<−0.5%.

3-8

ABL700 Series Reference Manual 3. The Optical System

Calibration

Calibration Materials

The optical system is calibrated in 2 points as follows:

• on the S1720 or S1730 Calibration Solution used for zero point calibration;

• on S7770 tHb Calibrating Solution with known ctHb and ctBil values

Zero Point

Cuvette Pathlength

in order to determine the zero point, , and the cuvette path length,

The zero point, , is the current (or intensity) measured by the photodiode array

l. I

on one of the transparent calibration solutions present in the cuvette. During a zero point calibration

is measured automatically during every calibration.

ctHb and ctBil are zero point calibrated.

The cuvette path length (i.e. the length of light path) is determined from LambertBeer’s Law by measuring the absorbance of the colored dye present in the tHb Calibration Solution (S7770), which has a known equivalent hemoglobin and bilirubin concentration:

Beer’s Law: A = ε × ctHb × l or A = ε × ctBil × l

where:

ctHb

ctBil

absorbance

= extinction coefficient

= concentration of Hb

= concentration of total bilirubin

tHb/tBil Calibration Frequency

= length of lightpath

It is recommended that a tHb calibration is performed every three months. Bilirubin is also calibrated during a tHb calibration.

3-9

3. The Optical System ABL700 Series Reference Manual

Measurement and Corrections

Oximetry parameters

The oximetry parameters are calculated as follows:

Parameter Equation

ctHb(meas)

FCOHb

FHHb

FMetHb

FHbF

= cO

Hb + cCOHb + cHHb + cMetHb

OHb

ceHb = cHHb + cO

OHb

COHb

HHb

tHb

MetHb

HbF

tHb

eHb

tHb

Hb (effective hemoglobin)

where:

Hb = concentration of oxyhemoglobin in the sample

Bilirubin

cCOHb = concentration of carboxyhemoglobin in the sample cHHb = concentration of deoxyhemoglobin in the sample cMetHb = concentration of methemoglobin in the sample cHbF = concentration of fetal hemoglobin in the sample

Bilirubin is calculated as follows:

tBil(B)

tBil(P)

Hct(calc)1

−

where:

ctBil(P) = concentration of total bilirubin in plasma ctBil(B) = concentration of diluted plasma bilirubin after sample

hemolyzation

Hct(calc) = calculated hematocrit (a fraction).

Continued on next page

3-10

ABL700 Series Reference Manual 3. The Optical System

Measurement and Corrections, Continued

Bilirubin (continued)

Restrictions

Hct(calc)

For further details on Hct(calc) please refer to Interference Tests and the explanation of MCHC (Mean Corpuscular Hemoglobin Concentration) in chapter 5 in this manual.

The following parameters will not be calculated:

Parameter Is not calculated if…

0 0301.

g/dL

tHb=×

sO2, FCOHb, FMetHb, FHHb

ceHb = cHHb + cO ctHb< 1 mmol/L

Hb< 0.75 mmol/L;

ctBil ctHb > 15.5 mmol/L

The following conditions are required to exclude HbF interference:

Parameter or Feature Requirement

ceHb > 3 mmol/L FCOHb < 15 % FMetHb < 10 %

“HbF correction" has not

been activated

If ctHb < 5 mmol/L, cO

mmol/L.

If ctHb > 5 mmol/L, cO

HbF should be more than 1

HbF/ctHb should be more

than 0.2.

“HbF correction" has

been activated

No lower limit value for cO

HbF is required, i.e.

even adult blood samples will be corrected for HbF.

It may be of value when analyzing blood samples from newborns who received adult blood transfusion.

In these cases FHbF can be lower than 20 % and

significant deviations of oximetry parameters and bilirubin can occur.

HbF suppression has been activated

The FHbF value is displayed by the ABL735/730.

Message “HbF detected” is displayed on the other analyzer versions with the oximetry module installed.

<50 % or

ctHb<5 mmol/L

Message “FHbF measurement is not possible” is

displayed by the ABL735/730 if a HbF suppression has been activated.

Continued on next page

3-11

3. The Optical System ABL700 Series Reference Manual

Measurement and Corrections, Continued

Corrections

The uncorrected measured total hemoglobin concentration, ctHb(sample), and total bilirubin concentration, ctBil(sample), are corrected for slight variations in the

cuvette path length between individual analyzers, using the following equations:

ctHb(sample,corr)

ctHb(sample)

= and ctBil(sample)

F F

cuv dil

ctBil(sample)

F F

cuv dil

where:

ctHb(sample)

= Measured total hemoglobin concentration from a sample

(uncorrected)

Corrections

ctBil(sample)

= Measured total bilirubin concentration from a sample

(uncorrected)

cuv

dil

= Analyzer dependent constant determined at tHb calibrations

= Analyzer dependent constant determined during tests against

the reference method, which corrects for Hb and bilirubin dilution in the different aspiration modes.

NOTE: The constant F

is different for ctHb and ctBil.

dil

Correction ABL735/730/725/720/715/710 – Syringe modes

dil

195 µL 95 µL 85 µL

1.0000 0.9707 1.0050

ABL735/730/725/720/715/710 – Capillary modesCorrection

195

µL 95 µL 85 µL 55 µL 35 µL

dil

1.0057 0.9707 1.0050 0.9460 0.9650

3-12

See Chapter 5, Performance Characteristics for more information on specification

tests.

ABL700 Series Reference Manual 3. The Optical System

References

List of References

The list of the references for Chapter 3, The Optical System:

1. Ewing GW. Instrumental methods of chemical analysis. 5

ed. McGraw-Hill,

1985.

2. Martens H. Multivariate calibration: quantitative interpretation of non-selective chemical data. Dr. Techn. Thesis, NTH Univ. of Trondheim, 1986.

3. Krzeminski A. Why correct for fetal hemoglobin in blood oximetry measurements? Radiometer Publication Info. No. 1992-3. Copenhagen: Radiometer Medical A/S, 1992.

4. Huehns ER, Beaven GH. Developmental changes in human hemoglobins. Clin Dev Med 1971; 37: 175-203.

3-13

Introduction

Contents

4. User-Defined Corrections

This chapter describes the basis of the user-defined corrections available for all the parameters that are measured in the ABL700 Series analyzers.

This chapter contains the following topics.

General Information ......................................................................................... 4-2

Correction Factors for Oximetry Parameters and Bilirubin ............................. 4-4

Electrolyte and Metabolite Parameters ............................................................ 4-8

4. User-Defined Corrections ABL700 Series Reference Manual

General Information

Purpose of Use

NOTE:

User-Defined Corrections

User-defined corrections are most commonly implemented in situations where the values measured for a particular parameter by two or more analyzers, deviate consistently from each other.

Since the performance of all ABL700 analyzers is tested as described in Chapter 5, Performance Characteristics, and each instrument is assumed to operate accurately and optimally, the unnecessary correction of parameter values by the user can lead to inaccurate measurements being reported.

User-defined corrections are based on a linear correlation between the measured values (without user-defined corrections) and the displayed values (with userdefined corrections).

The correction factors for each measured parameter are the slope and the offset of the correction line. With user-defined corrections it is possible to change the values of either one or both of these correction factors, depending on the parameter type.

Corrected value = Slope × Uncorrected value + Offset

The diagram below is a schematic representation of the relationship between correction lines without and with user-defined correction.

Displayed (corrected) parameter value

Correction line without user correction

Correction line with user correction

Slope = 1

Offset

Measured (uncorrected) parameter value

4-2

Continued on next page

ABL700 Series Reference Manual 4. User-Defined Corrections

General Information, Continued

Entering User-Defined Corrections

In the ABL700 Series analyzers the slope and the offset for each parameter are

configured via the Parameters Setup screen under General Setup. User corrected

values are marked with a “*” after the result.

NOTE: The user-defined corrections will also be applied to measurements on QC

solution.

For detailed instructions on how to enter user-defined corrections, refer to the

section Parameter Setup in Chapter 5 of the Operator’s Manual.

4-3

4. User-Defined Corrections ABL700 Series Reference Manual

Correction Factors for Oximetry Parameters and Bilirubin

Introduction

The following corrections can be user-defined for the oximetry parameters and bilirubin:

Parameter Allowed User-defined Corrections

ctHb

FCOHb

FMetHb

FO Hb

FHHb FHbF

ctBil

Slope Offset

Yes No

Yes Yes

No Yes

No No

Yes Yes

NOTE: In order to define the corrections accurately, the measurements of the

oximetry parameters and bilirubin on the ABL700 Series analyzers should be made without any entered corrections. To avoid truncation errors from an enabled “Out of range suppression” function it is important to disable the function.

The following recommendations apply to ctHb:

Item Description

Units g/dL; g/L; mmol/L

Sample

Set ctHb of a SAT100 sample to ≈15 g/dL (9.3 mmol/L) and pH ≈ 7.4

ctHb, maximum

Uncorrected or corrected: ≈ 15 g/dL or 9.3 mmol/L

point Slope 0.950 - 1.050

Continued on next page

4-4

Radiometer ABL-700, ABL-800 Reference manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Contents

1. Introduction

ABL700 Series Documentation

Warnings/Cautions and Notes

2. Electrodes

General Construction

General Measuring Principles

Calibration

Electrode Measuring Time and Updatings

Reference Electrode

pH Electrode

pCO2 Electrode

pO2 Electrode

Electrolyte Electrodes

Metabolite Electrodes

References

3. The Optical System

Measuring Principle

Correcting for Interferences

Calibration

Measurement and Corrections

References

4. User-Defined Corrections

General Information

Correction Factors for Oximetry Parameters and Bilirubin