Elementar Analysensysteme GmbH vario EL cube Operating Instructions Manual
Variants Operating Instructions
vario EL cube
Analyzer
Version 17.02.2017
Elementar Analysensysteme GmbH
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
Copyright ©Elementar Analysensysteme GmbH
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This document contains proprietary information of Elementar Analysensysteme GmbH. Reprint is
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and intellectual property contained herein is confidential between Elementar Analysensysteme GmbH
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Elementar Analysensysteme GmbH
Elementar-Straße 1
63505 Langenselbold
Germany
+49 (0) 6184 9393 0
E-Mail: info@elementar.de
Internet: http://www.elementar.de
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
Contents 3
Contents
CHAPTER 1 General 7
Revision history ............................................................................................................................................. 8
About this document ...................................................................................................................................... 9
Display conventions .................................................................................................................................... 10
Working with the operating instructions ....................................................................................................... 10
General information on the operating instructions ....................................................................................... 10
Notes regarding modification ....................................................................................................................... 11
Warning notes during operation .................................................................................................................. 11
CHAPTER 2 Oxygen determination with TCD 13
Analytical characteristics and technical specifications ................................................................................. 14
Substance digestion and functional diagram ............................................................................................... 14
Separation of the reaction gases ................................................................................................................. 17
Detection ..................................................................................................................................................... 17
Tube fillings ................................................................................................................................................. 18
Modification to O Mode ............................................................................................................................... 19
Conditioning the pyrolysis tube ................................................................................................................... 23
Changing of the pyrolysis crucible ............................................................................................................... 24
Establishing of the analysis readiness ......................................................................................................... 25
Notes on performing calibration .................................................................................................................. 26
Oxygen analyses in routine operation ................................ ................................................................ ......... 27
Application notes for oxygen determination ................................................................................................. 29
Pyrolysis temperature ...................................................................................................................... 30
Difficult matrices ............................................................................................................................... 30
Lifetime of the pyrolysis tube ............................................................................................................ 31
Additional error messages in O mode ......................................................................................................... 32
CHAPTER 3 Oxygen determination with NDIR 33
Analytical characteristics and technical specifications ................................................................................. 34
Substance digestion and functional diagram ............................................................................................... 34
Detection ..................................................................................................................................................... 38
Tube fillings ................................................................................................................................................. 38
Modification to O Mode ............................................................................................................................... 40
Conditioning the pyrolysis tube ................................................................................................................... 46
Changing of the pyrolysis crucible ............................................................................................................... 47
Establishing of the analysis readiness ......................................................................................................... 48
Notes on performing calibration .................................................................................................................. 49
Oxygen analyses in routine operation ................................ ................................................................ ......... 50
Application notes for oxygen determination ................................................................................................. 52
Pyrolysis temperature ...................................................................................................................... 53
Difficult matrices ............................................................................................................................... 53
Lifetime of the pyrolysis tube ............................................................................................................ 54
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
Contents 4
Additional error messages in O mode ......................................................................................................... 55
CHAPTER 4 Oxygen determination with combined NDIR for measuring CO and SO2 57
Analytical characteristics and technical specifications ................................................................................. 58
Substance digestion and functional diagram ............................................................................................... 58
Detection ..................................................................................................................................................... 62
Tube fillings ................................................................................................................................................. 62
Modification to O Mode ............................................................................................................................... 64
Conditioning the pyrolysis tube ................................................................................................................... 71
Changing of the pyrolysis crucible ............................................................................................................... 72
Establishing of the analysis readiness ......................................................................................................... 73
Notes on performing calibration .................................................................................................................. 74
Oxygen analyses in routine operation ................................ ................................................................ ......... 74
Application notes for oxygen determination ................................................................................................. 76
Pyrolysis temperature ...................................................................................................................... 77
Difficult matrices ............................................................................................................................... 77
Lifetime of the pyrolysis tube ............................................................................................................ 78
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
Contents 5
Additional error messages in O mode ......................................................................................................... 79
CHAPTER 5 Sulfur determination with NDIR 81
Special features........................................................................................................................................... 82
Functional diagram ...................................................................................................................................... 83
Modification to S operation .......................................................................................................................... 84
CHAPTER 6 Sulfur determination with combined NDIR for measuring CO and SO2 89
Special features........................................................................................................................................... 90
Functional diagram ...................................................................................................................................... 91
Modification to S operation .......................................................................................................................... 92
CHAPTER 7 Chlorine determination with EC cell 97
Analytical characteristics and technical specifications ................................................................................. 98
Substance digestion and functional diagram ............................................................................................... 98
Detection ................................................................................................................................................... 100
Tube fillings ............................................................................................................................................... 100
Notes on performing calibration ................................................................................................................ 102
Chlorine analyses in routine operation ...................................................................................................... 103
Notes on sensitivity and measuring range ................................................................................................. 104
Cross-sensitivity of the EC cells ................................................................................................................ 105
Quantitative conversion from Cl to HCl ..................................................................................................... 106
Maintenance of the HCl EC cells ............................................................................................................... 106
Leak test .................................................................................................................................................... 107
Modification to Cl operation ................................................................................................ ....................... 108
CHAPTER 8 TIC solids module 115
General information ................................................................................................................................... 116
Scope of delivery ....................................................................................................................................... 116
Safety instructions ..................................................................................................................................... 116
Technical specifications ............................................................................................................................ 117
Analytical characteristics ........................................................................................................................... 118
Functional diagram TIC module ................................................................................................................ 119
The components........................................................................................................................................ 121
Tube fillings ............................................................................................................................................... 121
Installation and initial start up of the TIC module ....................................................................................... 123
Selecting the operating mode .................................................................................................................... 126
General measuring principle TIC ............................................................................................................... 127
Analysis run ............................................................................................................................................... 128
Defining custom standard substances ....................................................................................................... 130
Maintenance work ..................................................................................................................................... 130
CHAPTER 9 CHNS determination with the liquid autosampler vario LS 133
CHNS determination with vario LS ............................................................................................................ 134
Tube fillings ............................................................................................................................................... 137
Selecting the operating mode .................................................................................................................... 139
CHNS routine operation ............................................................................................................................ 139
Setting device parameters ......................................................................................................................... 139
Defining custom standard substances ....................................................................................................... 142
Defining custom methods .......................................................................................................................... 142
Modification into CHNS liquid mode .......................................................................................................... 143
Calibration ................................................................................................................................................. 145
View of the analytical results ..................................................................................................................... 147
Check list, prior to the analysis run ............................................................................................................ 147
Shut-down for measuring breaks............................................................................................................... 148
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
Contents 6
CHAPTER 10 CHN determination with the liquid autosampler vario LS 149
CHN determination with vario LS .............................................................................................................. 150
Tube fillings ............................................................................................................................................... 153
Selecting the operating mode .................................................................................................................... 155
CHN routine operation ............................................................................................................................... 155
Setting device parameters ......................................................................................................................... 156
Defining custom standard substances ....................................................................................................... 158
Defining custom methods .......................................................................................................................... 158
Modification into CHN liquid mode ............................................................................................................ 159
Calibration ................................................................................................................................................. 161
View of the analytical results ..................................................................................................................... 163
Check list, prior to the analysis run ............................................................................................................ 163
Shut-down for measuring breaks............................................................................................................... 164
CHAPTER 11 Upgrade kit for manual injection 165
Scope of the upgrade kit for manual injection ........................................................................................... 166
Removal of components not needed ......................................................................................................... 167
Installation of the required parts ................................................................................................................ 168
Functional diagram varioELcube CHNS ................................................................................................ .... 170
Functional diagram varioMACROcube CHN ............................................................................................. 172
Functional diagram varioMACROcube CHNS ........................................................................................... 174
Functional diagram varioMICROcube ....................................................................................................... 176
CHAPTER 12 Modification kit for special applications 179
Removing/installing and conditioning the special reaction tubes ............................................................... 180
Removing the special reaction tubes from the furnace .................................................................. 181
Installing special reaction tubes in the furnace and conditioning .................................................... 183
Emptying and filling special reaction tubes ................................................................................................ 188
Emptying special reaction tubes, CHNS / CNS / S mode ............................................................... 189
Filling the special reduction tube, CHNS / CNS / S mode .............................................................. 189
Filling the special combustion tube, CHNS / CNS / S mode .......................................................... 191
Emptying special reaction tubes, CHN / CN / N mode ................................................................... 194
Filling the special reduction tube, CHN/ CN/ N mode..................................................................... 194
Filling the special combustion tube, CHN/ CN/ N mode ................................................................. 196
Index 199
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
Purpose
In this chapter
Revision history .............................................................................................................................. 8
About this document ....................................................................................................................... 9
Display conventions .......................................................................................................................10
Working with the operating instructions .........................................................................................10
General information on the operating instructions .........................................................................10
Notes regarding modification .........................................................................................................11
Warning notes during operation ....................................................................................................11
C H A P T E R 1
General
This chapter contains general topics of the document.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
1 - General 8
Revision history
Date
Modification
20.10.2011
Creation.
03.04.2012
Tube 309 omitted.
29.05.2012
Length of empty ash finger in the Cl combustion tube modified.
02.01.2013
Replacing the tube no. 61 (omitted) to no. 108 (added)
14.05.2013
Picture with tube no. 108 removed
14.08.2013
Chapter "Manual injection" added
12.11.2013
Chapter "Modification kit for special applications" added.
18.06.2014
Desorption temperature CO from 260°C to 150°C changed.
19.11.2014
made different small text changes
09.06.2016
Reduction tube filling in CHNS mode with VLS changed
23.08.2016
Combustion tube and reduction tube filling in the CHNS mode with VLS
changed and made further small edits.
15.09.2016
Change of address Langenselbold
17.02.2017
Contents checked
List of modifications in this document up to now
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
1 - General 9
About this document
Status of the operating instructions
The status of the operating instructions is: 17.02.2017.
Identification number
The operating instructions identification number is: 19.00-5006.
Validity
The operating instructions are valid for all instruments as from serial number: 19105046.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
1 - General 10
Display conventions
Formatting convention
Type of information
Triangular bullet ()
Step by step procedure. You can follow these instructions to
complete a specific task.
Special bold
Items you must select, such as menu options (e. g. File > New),
command buttons (e. g. Cancel), or common accentuation.
Italics
Used to emphasize the importance of an item or for variable
expressions such as parameters.
CAPITALS
Names of keys on the keyboard, for example, SHIFT, CTRL, or
ALT.
KEY+KEY
Key combinations for which the user must press and hold down
one key and then press another, for example, CTRL+P, or
ALT+F4.
"Quotation marks"
Denote amongst others the names of dialogs in the software, e. g.
the "Replace part" dialog.
{Symbolic name}
Denotes a symbolic name, e. g. {Element} stands for the
corresponding name of an element.
Before you start using this guide, it is important to understand the terms and typographical
conventions used in the documentation. The following kinds of formatting in the text identify special
information.
Working with the operating instructions
Operating the analyzer
Read the operating instructions thoroughly before performing work with the analyzer.
Storing the operating instructions
Store the operating instructions carefully and make sure the instructions are accessible for all relevant
personnel.
Passing on the operating instructions
If you pass on the analyzer, always pass on the operating instructions, too.
General information on the operating instructions
Pictures
The instruments of Elementar underlie a permanent development and adjustment regarding the
optimum parameter settings. This may lead to deviations in terms of picture display of the manual and
the current instrument status which are not relevant for the understanding of the instrument operation.
The valid numbers of the parameter settings and/or variables can be found in the current text part.
Therefore, numbers in the pictures of software dialogs are mainly replaced by spaces or only reflect
examples. They do not reflect the proper, recommended set values.
Reading aids
Subheadings are displayed in the left margin as reading aids. They sum up the content of the
particular section and are useful for quick navigation.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
1 - General 11
Index
Warning
Gas pressure and caustic substances in the instrument
Consumables may escape under pressure and cause chemical burns. Before
performing the work:
Shut off the gas supply. To do so, execute the Options > Maintenance >
Replace parts command.
Caution
Lack of ventilation of the analyzer!
A lack of ventilation leads to overheating of the analyzer. Before you switch off the
instrument:
Ste the setpoint temperatures of the furnaces to 0 °C. To do so execute the
command Options > Settings > Parameter > Temperatures
Allow the furnaces to cool down until the temperature displayed is less than
55 °C
Warning
Hot components in the instrument
When working inside the instrument there is a risk of burning as many parts of the
instrument are hot.
When working inside the instrument always wear protective glasses and the
enclosed heat protection gloves.
An index is given at the end of the operating instructions that helps you locate certain topics more
easily. Index entries always refer to the first page of the section in which the index term is found.
Therefore, don't be confused if the index term does not appear on the first page but rather on one of
the following pages.
Notes regarding modification
Note
Due to the modular design of the analyzer, a large variety of modifications are possible. The individual
modifications described in these instructions are limited to established scenerios in order to keep the
comprehensiveness of the instructions within certain limits.
Warning notes during operation
Note
Always pay attention to careful handling when working with the instrument, especially for
modifications, maintenance and repairing works. The following notes have to be strictly observed
when performing the corresponding works.
Also observe the safety and warning notes in the operating instructions of the basic instrument.
Gas pressure
Please observe the following instruction:
Switching off the instrument
Please observe the following instruction:
Hot instrument parts
Please observe the following instruction:
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
1 - General 12
Changing mode
Caution
Overheating if tube fillings are not appropriate for the operating mode!
Overheated tube fillings melt, run into the furnace area and destroy the furnace.
Make sure that the tube fillings correspond to the selected operating mode.
Warning
Sharp pieces of broken glass!
When cold quartz or glass components break there is a risk of cut injuries.
Wear the enclosed protective leather gloves and protective glasses when
handling cold quartz and glass parts.
Caution
Cutting sealing elements apart/out (o-rings, quad rings, half shells, ferrules).
When cutting sealing elements apart/out with a knife you may damage sealing
surfaces.
Never remove sealing elements with a knife but rather with tweezers.
Warning
Hot components in the instrument
When working inside the instrument there is a risk of burning as many parts of the
instrument are hot.
When working inside the instrument always wear protective glasses and the
enclosed heat protection gloves.
Caution
Overheating if tube fillings are not appropriate for the operating mode!
Overheated tube fillings melt, run into the furnace area and destroy the furnace.
Make sure that the tube fillings correspond to the selected operating mode.
Please observe the following instruction:
Filling reaction tubes
Please observe the following instructions:
Installing and conditioning the reaction tubes
Please observe the following instructions:
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
Target group
In this chapter
Analytical characteristics and technical specifications ...................................................................14
Substance digestion and functional diagram .................................................................................14
Separation of the reaction gases ...................................................................................................17
Detection .......................................................................................................................................17
Tube fillings ...................................................................................................................................18
Modification to O Mode ..................................................................................................................19
Conditioning the pyrolysis tube ......................................................................................................23
Changing of the pyrolysis crucible .................................................................................................24
Establishing of the analysis readiness ...........................................................................................25
Notes on performing calibration .....................................................................................................26
Oxygen analyses in routine operation ...........................................................................................27
Application notes for oxygen determination ...................................................................................29
Additional error messages in O mode ...........................................................................................32
C H A P T E R 2
Oxygen determination with TCD
Personnel involved with the instrument.
Purpose
This section describes the special features of the oxygen determination with TCD.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 14
Analytical characteristics and technical specifications
Analytical characteristic
Comments
Analysis method
Oxygen determination by pyrolysis of samples, separation of
foreign gases, separation of the desired measuring components,
thermal conductivity detection.
Detector
Thermal conductivity detector (TCD)
Sample weight/sample volume
Approx. < 1 to 10 mg depending on the substance.
Working range
(depending on kit and measuring
mode)
O: 0.03 - 5 mg
Precision / standard deviation
<0,2 % with benzoic acid (approx. 2 mg)
Duration of analysis
(depending on element content
and sample weight)
O: 8 - 15 min
Calibration
Linear and non-linear curve adjustment; total work range.
Data storage and data output
Storage on hard disk or external storage media.
LIMS transfer possible.
Data output to screen and printer.
Reference value
Technical specifications
Supply gases
Helium, purity 99.995%
Consumption of supply gases
Per analysis approx. 1.4 to 2.6 liters helium
Phase
Process
1
The substance to be analyzed is digested in reductive atmosphere at a temperature of
approx. 1,170 °C by means of pyrolysis (cracking).
Analytical characteristics
The following table explains the analytical characteristics:
Technical specifications
The following table contains the technical specifications of the gas supply:
Substance digestion and functional diagram
Introduction
The following section explains:
Which procedures in the pyrolysis tube of the furnace are processed.
How the reaction gas mixture is prepared for adsorption and separation into its constituents.
Processes during substance digestion and preparation of the reaction gas mixture
The substance digestion will be improved with and additive of approx. 8 mg polyethylene (PE)
(temporarily there is a H2 concentration of > 10% in ambiance of the sample).
The O recovery becomes more matrix independent. The PE can be inserted in the carousel in a
second boat.
Substance digestion and preparation of the reaction gas mixture is divided into the following phases:
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 15
2
For the digestion weigh in the sample into silver boats (for liquid samples silver capsules are
available). The folded boat is thrown into the quartz glass pyrolysis tube by means of an
autosampler.
3
The oxygen containing radicals formed in the pyrolysis tube are converted quantitatively at a
carbon contact (special carbon black) into carbon monoxide (Boudouard equilibrium).
4
Acidic pyrolysis products like e.g. H2S, HCN, HCl etc. are absorbed at NaOH by means of
an absorption tube which is downstream of the pyrolysis tube.
5
Usually, water is set free during the reaction of NaOH with an acidic medium. Therefore, the
gas mixture is dried once again after the NaOH layer.
6
Other pyrolysis products like e.g. N2 and CH4 are led to a separation and measuring system
together with the carbon monoxide to be detected.
2 - Oxygen determination with TCD 16
Notes
Two-way valve
Pressure sensor
Gas separation
For a better understanding see also the following illustration (tubing diagram, oxygen determination).
Symbols
The following list names the functional and basic symbols:
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 17
Three-way valve
Loop
Measuring cell
Check valve
Heated tube
Sensor
Throttle
Drying
Hose line
Flow controller
Combustion
Copper tube
Flow sensor
Post combustion
Reduction
Pressure contoller
Actuator
Phase
Process
1
The gas mixture of CO and the by-products N2, H2and CH4 flow through the adsorption
column at a temperature of 40 °C.
Thus, the CO is removed quantitatively from the gas stream.
2
As the first component, the by-products unaffected by the adsorption column enter into the
TCD together with the carrier gas helium.
3
The measurement of the N2, H2 and CH4 fractions takes place. The result is ignored
(dummy peak).
4
The adsorption column loaded with CO is heated up to 150°C whereby the CO is desorbed
quickly and flushed by helium into the TCD.
5
A fan cools the adsorption column to cooling temperature of 40 °C and, thus making it ready
for the next analysis sample.
Separation of the reaction gases
Introduction
The following section explains how the individual measuring components in the reaction gas mixture
are separated from each other.
Procedures during separation
The separation of the measuring components is divided into the following phases:
Note
Samples containing fluorine and phosphorus may cause false O results. Fluorine my cause damages
in the instrument, particulary at the quartz parts. Alkaline, earth alkaline and sulfurous samples have
to be loaded with a 1:1 mixture of hexamethylentetramine and ammonia chloride. When measuring
heavy alkaline/earth alkaline samples the pyrolysis tube will corrode.
Detection
Introduction
The method of detection is described under Detection of measuring components and evaluation of
the measuring signal in the vario EL cube operating instructions.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 18
Variations relevant for the oxygen determination
Legend:
1 Ash finger (used as protection tube)
2 Ash crucible
3 Graphite felt (10 mm)
4 Carbon black (55 mm)
5 Support rod (110 mm)
6 Quartz chips, coarse (2-4 mm)
7 Quartz wool (2 mm)
O integration
After the dummy peak integration has been finished, the following is possible:
Directly heat-out the CO collected on the adsorption column (approx. 260°C).
Heat-up the adsorption column to an "interim temperature" (approx. 60°C) in order to
separate hydrocarbons from the CO if necessary.
Prior to the start of the CO integration, another autozero alignment is carried out.
The O integration has been finished if the process time "peak anticipation time for O" (factory set
to 150 sec) has expired, and the dector signal is smaller than the cut-off threshold "O peak"
(defined internally).
Tube fillings
Requirements:
Before starting work, the following requirements must be met:
All quartz and glass components must be cleaned before their usage. Clean the tubes from
fingerprints by means of a suitable solvent (e.g. acetone) before installing. Otherwise there is a
risk of crystallization which will lead to premature ageing of the quartz.
Use chemicals necessary for the tube fillings only in the appropriate quality. Delivery directly from
the instrument manufacturer.
Safety instruction
Strictly observe the safety instruction "Filling reaction tubes" under Warning notes during operation
(on page 11).
Filling of the quartz pyrolysis tube (crack tube) for O determination
The arrangement of the filling must be carried out as shown in the following illustration.
The insert in the core of the tube contains the solid pyrolysis residue as well as the melted silver from
the silver boats.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 19
Removal of traces of moisture and other contaminations from the carrier gas
Legend:
1 Cotton
2 NaOH
3 Quartz wool (10 mm)
4 Sicapent®
5 Gas inlet
For gas drying insert commercial cleaning cartridges between gas delivery point and instrument, if
necessary.
Humid carrier gas causes a CO base which will be collected as a blank on the adsorption column.
Filling the NaOH absorption tube
The following picture shows the filling of the absorbtion tube:
Proceed as follows:
Fill the tube with NaOH (on carrier) and with Sicapent® (identical fill heights).
Close the tube ends with cotton.
Insert the NaOH tube into the already mounted clamps at the left side of the combustion furnace.
Modification to O Mode
Scope of the modification kit for oxygen determination
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
All parts necessary for the tube modification are included in the O upgrade kit for detecting oxygen
with TCD and are labeled with numbers.
2 - Oxygen determination with TCD 20
Legend:
4 Pyrolysis tube
5 Glass tube
9 Insulation plug
10 Adsorption column
14 Quad ring, black
15 Ball
16 Ground-in clamp
35 Pan, closed
37 Tube no. 46
38 Hose line no. 47
39 Hose line no. 48
40 Combustion tube flange
42 Hose line no. 10
Safety instruction
Note
Process
Phase 1: Removal of components not needed
The following parts are also part of the kit but are not pictured.
Sheath tube
Ash crucible
D-sub-adapter
Software update CD.
Strictly observe the safety instruction "Gas pressure" under Warning notes during operation (on
page 11).
To remove/install the tubes proceed as described in chapter Removing standard reaction tubes of the
vario EL cube main operating instructions.
The modification is divided into the following phases:
Removal of components not needed
Modification
Installation of components necessary for the O operation
Proceed as follows:
Before starting the installation of the pyrolysis tube, remove the components as following listed:
O2 supply line
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 21
Quartz glass bridge
Combustion tube
Reduction tube with plug
Tube no. 108 (heated)
These components are not needed for the oxygen operation mode.
Phase 2: Modification
Safety instruction
Strictly observe the safety instruction "Hot instrument parts" under Warning notes during operation
(on page 11).
Proceed as follows:
Open the right side door.
Loosen the plug of the heating cartridge holder (X47) and close the right side door.
Note: For a modification to a mode with quartz glass bridge, the plug of the heating cartridge
holder has to be plugged back into socket X47!
Open the front door.
Remove the heat protection below the furnace.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 22
If not already done, loosen all connections to the reaction tubes.
Pull the furnace out of the instrument.
Remove the ground-in clamps, the quartz glass bridge and the combustion tubes.
Phase 3: Installation of components necessary for the O operation
The numbers shown in parentheses refer to the illustration above "Scope of the upgrade kit".
Proceed as follows:
Insert the pyrolysis tube (4) which is filled and mounted with the combustion tube flange (40) into
the right tube of the furnace.
Note:
The top o-ring used for sealing of the bayonet catch has to be checked frequently for mechanical
damages and replaced if necessary.
Push carefully the filled absorption tube (5) into the clamps located at the left side of the furnace.
Observe that the NaOH layer is on the bottom (gas inlet).
Connect the pyrolysis tube outlet with the NaOH tube inlet by means of the tube No. 46 (37).
Push the furnace back into the instrument.
Connect the outlet of the NaOH absorption tube (top) with tube no. 47 (38). Connect the other
end of the tube by means of the ground-in clamp to the ball of hose line no. 10 located at the
instrument.
For that purpose the ball joint has to be turned to 90° and pushed into the appropriate clamp.
Close the left heating tube by means of the insulation plug (9).
Fasten the pyrolysis tube to the ball valve by means of the bayonet catch. The centering bolt has
to be within the notch of the centering angle (lock against rotation).
Close the tube 26 with the ball (15) and ground-in clamp (16).
Close the open tube at the combustion tube flange with the pan (35).
Exchange the CO2 adsorptions column against the CO adsorption column (10).
Proceed as described under Removing/installing and conditioning the adsorption column of the
vario EL cube main operating instructions.
Connect tube no. 10 (42) with the CO column (10) by means of the ground-in clamp.
The modification has now been completed and the instrument is ready for the O determination in
routine operation.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 23
View after the modification has been completed
The following picture shows the oxygen mode after the modification has been completed.
Conditioning the pyrolysis tube
Introduction
The following section describes in detail how to condition the pyrolysis tube.
Prior to routine analysis the pyrolysis tube has to be conditioned. For this purpose flush the carbon
black filling for approx. 12 hours at 1,170°C under helium in the instrument; subsequently, analyze 5
samples polyethylene (weight 8 mg).
Conditioning the pyrolysis tube
Proceed as follows:
Turn on PC and printer. Wait until the boot process has been finished.
Switch on the instrument.
The instrument performs now a reference run of the ball valve and autosampler.
Switch on the operating gas. Set the intake pressure at the delivery point to 0.5 bar.
Open the gas connection to the NaOH tube.
Connect tube no. 48 with the outlet of the pyrolysis tube. Lead the end of the hose line through
the crack in the door into the open. The front door has to be closed.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 24
Note
Connect th end of tube no. 48 with the furnished black hose (Article No. 03 651 010, 25 m) and
lead the gases resulting from conditioning (e.g. H2S, water vapor) into an exhaust hood or into
the open.
Start the instrument software and select in the menu System > Mode the operation mode "O",
option "TCD" checked.
Leave the mode menu by clicking OK; if necessary a new initialization of the instrument occures.
To heat up the furnace call the menu Options > Settings > Parameters. Set the temperature of
oven 1 to 1170 °C.
Note: The modification of the instrument parameters is only possible with the appropriate
access rights.
After reaching the setpoint temperture (after approx. 1.5 hours) heat-out the pyrolysis tube for
another 12 hours (over night).
Remove tube no. 48.
Connect the 25 m long exhaust hose with the outlet at the instrument rear.
Close the gas connection at the NaOH tube and adjust the intake pressure at the delivery point
until the PC displays a pressure of approx. 1.2 bar.
Analyze 5 samples polyethylene each 8 mg (conditioning) and 10 samples benzoic acid each
approx. 1.5 mg (stability test) after the flush process.
Now the instrument is ready for the O determination in routine operation.
Samples containing fluorine and phosphorus may cause false O results. Fluorine my cause damages
in the instrument, particulary at the quartz parts. Alkaline, earth alkaline and sulfurous samples have
to be loaded with a 1:1 mixture of hexamethylentetramine and ammonia chloride. When measuring
heavy alkaline/earth alkaline samples the pyrolysis tube will corrode.
Changing of the pyrolysis crucible
Changing of the pyrolysis crucible
In addition to the common maintanance work, the replacement of the pyrolysis crucible for oxygen
determination will be described here. The crucbile has to be emptied after approx. 80 samples, if you
work with the polyethylene additive.
Safety instruction
Strictly observe the safety instruction "Hot instrument parts" under Warning notes during operation
(on page 11).
Proceed as follows:
Cool the furnace down to approx. 600°C.
Open the front door.
Initiate a pressure drop by clicking the menu command Options > Maintenance > Replace
parts.
After completion of the pressure drop procedure detach the ground-in clamp at the NaOH tube
outlet.
Open the bayonet catch at the ball valve.
Pull the furnace out of the instrument.
Pull the combustion tube flange out of the pyrolysis tube.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 25
Pull the sheath tube and the crucible with the tongs out of the pyrolysis tube.
Empty the crucible.
Install...
... either the emptied crucible once again, or
... a new crucible immediately after the filled crucible has been removed. This has to be
conditioned by running 5 samples polyethylene (weight 8 mg).See Conditioning the
pyrolysis tube TCD (on page 23).
Push the furnace into the instrument. Observe that the ball valve adaptor is centered in the
bayonet catch.
Close both the bayonet catch at the ball valve and the ground-in ball-and-socket joint at the
NaOH tube.
Leave the "Replace part" dialog by clicking Finish.
Flush the apparatus for approx. 1 hour and set the furnace temperature back to 1,170 °C.
Wait until the PC display of the baseline of the detector is stable.
The flushing time depends on the amount of atmospheric nitrogen penetrated into the apparatus
during the replacement of the tube insert.
In unpropitious cases, the flushing procedure can last up to 45 minutes.
Establishing of the analysis readiness
Establishing of the analysis readiness
Proceed as follows:
Turn on PC and printer and wait until the boot process has been completed.
Switch on the instrument.
The instrument performs now a reference run of the ball valve and carousel.
Switch on the operating gases.
Launch the operating software.
Open the "Analysis mode" dialog in the operating software by selecting System > Mode. Select
the desired operation mode ("O" for oxygen).
Set the detector mode to "TCD".
Leave the mode dialog by clicking OK; a re-initialization of the system takes place.
Defining test/standard substances
By means of the menu Options > Settings > Standards you can see whether the test substances to
be used are stored there.
A description how to define a new and/or modify an existing standard is given under Edit standard
samples in the vario EL cube operating instructions.
If no modifications have been carried out in the standard samples dialog, leave it by clicking Close,
otherwise by clicking Save followed by Close.
Note:
If the value "0" stands for the element content percentage of a test substance, this test substance will
be ignored for the respective element during calibration and/or during the calculation of the daily
factor.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 26
Routine operation
For a description of the particular software terms refer to Menu and dialog descriptions in the vario EL
cube operating instructions.
Setting the furnace temperature
Proceed as follows:
Open the "Device parameter" dialog in the operating software by selecting Options > Settings >
Parameters.
Check and/or enter the following oven temperature (oven 2 is not needed here):
For operating mode O: Pyrolysis tube (oven 1): 1170 °C
Leave the dialog by clicking OK (or by clicking Cancel). The modules are now re-initialized if
necessary.
In the sataus view you can observe how the temperature of oven 1 increases.
The heat-up time takes approx. 60 minutes.
For an optimum lifetime of the instrument, the tubes and the consumables, we recommend to
leave the instrument turned on.
Once the setpoint temperature has been reached the instrument is ready to measure.
Notes on performing calibration
Background
The calibration serves for creating a correlation between the measured peak area of the individual
element and the concentration of the element in the sample.
This correlation is established via the so called calibration coefficients which are calculated from the
calibration run.
Checking the calibration
Prior to the beginning of each series of measurements, it has to be checked if the instrument is
calibrated.
Proceed as follows:
Open the "Calibration coefficients" dialog in the operating software by selecting Math. >
Coefficients.
The coefficients dialog allows manual input of the calibration coefficients as well as of the limit
values of the corresponding calibration range.
Sample weights
In practice, the following sample sequence has proven for a measuring range of 0.03 mg to 2.0 mg O:
10 conditioning samples of benzoic acid, approx. 2 -3 mg each for O conditioning
3 conditioning samples, 0.1-0.15 mg each
27 samples with sample weights as follows:
0.1 - 0.1 - 0.15 - 0.2 - 0.25 - 0.3 - 0.4 - 0.5 - 0.6 - 0.7 - 0.8 - 0.9 - 1.0 - 1.5 - 2.0 - 2.5 - 3.0 - 4.0 -
4.5 - 5.0 - 5.5 - 6.0 - 6.5 - 7.0 - 7.5 - 8.0 mg.
If the measuring range is to be extended, the following sample weights can be added:
Benzoic acid 9 - 10 - 12 - 14 - 16 - 18- 19 mg.
Thus, a measuring range up to 5 mg absolute oxygen will be covered.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 27
Polyethylene additive
Sample weight
polyethylene
Blank value area
8,014
504
8,03
508
8,04
505
8,006
502
The poylethylene additive improves the absolute accuracy and/or recovery. In practise an addition of
approx. 8.0 mg per sample has proven to be of value.
Attention should be paid to:
Conditional of manufacturing, polyethylene contains minor concentrations of oxygen (approx. 0.2 ...
0.4%).
Prior to a measuring series start, especially during the calibation, the blank value of the used
polyethylene has to be determined. Enter the blank value area in the column "O-blank", e.g. the mean
value from 4 or 5 measurements.
Example:
The mean value of the blank value area is 505 and has to be entered for the analysis samples /
calibration samples in the column "O-blanks".
To ensure a correct calculation of the calibration select the manual calculation under Options >
Settings > Calculation > Blank Value Determination > Manual Input.
Subsequently, start the calcuation of the calibration under Math. > Calibrate, where the mathematical
treatment of the blank values is done automatically.
Oxygen analyses in routine operation
Sample sequence
In routine operation, the following sample sequence (if necessary with PE additive of each 8 mg per
sample) is recommended:
3 x conditioning sample (approx. 2.0 mg benzoic acid)
4 x benzoic acid (approx. 2.0 mg) for the determination of the daily factor
20 real samples
3 x benzoic acid (approx. 2.0 mg) for the monitoring of the daily factor
20 real samples
3 x benzoic acid (approx. 2.0 mg) etc.
The sample weight values can be entered either directly from a connected balance or manually via
the keyboard.
Parameter menu settings
The instrument has factory set analysis parameters for test substances defined in the standards
menu (e.g. acetanilide, benzoic acid).
Note: The modification of the instrument parameters is only possible with the appropriate
access rights.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 28
Temperature parameters
Parameter
Meaning
Factory setting
Oven 1 (pyrolysis tube) in O
mode
Pyrolysis tube
1,170 °C
Furnace 2
not used
Ads. col. standby
Adsorption temperature of the CO column
40 °C
Adsorp. column, Cooling temp.
At the end of analysis, the program waits until
column temperature drops below this value.
50 °C
Parameter
Meaning
Factory setting
Flushing time
Time in which the blind hole of the ball valve
is flushed, so the atmospheric oxygen will be
removed.
10 s
Integrator reset delay dummy
This time comes into effect for the first peak
of the respective operation mode after the
sample is fed and prevents the ensuing
detector instabilities from being jointly
integrated.
2 sec, operating
mode O
Integrator reset delay peak O
See above.
2 s
Desorpt. mid.
1 s
Parameter
Meaning
Factory setting
Autozero delay dummy
On starting up, the autozero alignment is
carried out after the autozero delay.
2 sec, operating
mode O
Autozero delay O
See above.
2 s
Peak Anticipation dummy
The anticiaption time comes into effect after
the integrator reset. During this time the
integrator waits for a measuring peak. If the
measuring peak does not appear within this
time, the integration is concluded and the
next analysis is started.
250 s
Peak anticipation O
See above.
150 s
Desorpt. O
Corresponds to the desorption temperature of
the column in O/TCD mode.
260 °C
Desorpt. midtemp.
40 °C
The following table shows the pre-set temperatures and explains the meaning of the parameters:
Time parameters
The following table shows the pre-set times and explains the meaning of the parameters:
Further process times and parameters are set via the "Method" dialog:
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 29
Application notes for oxygen determination
In this section
Pyrolysis temperature ....................................................................................................................30
Difficult matrices ............................................................................................................................30
Lifetime of the pyrolysis tube .........................................................................................................31
Target group
Personnel with basic knowledge of chemistry and experience with laboratory work, e. g. chemistry
laboratory workers.
Purpose
This section gives additional notes about the application for oxygen determination.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
2 - Oxygen determination with TCD 30
Pyrolysis temperature
Pyrolysis temperature
The method provides correct results only, if the carbon black filling in the pyrolysis tube is operated at
a temperature of at least 1120°C.
In order to set the correct pyrolysis temperature, some samples of benzoic acid (approx. 2,0 mg) are
analyzed with different pyrolysis temperatures.
The optimum temperature value has been reached if the analysis results with the increase of
temperature do no longer vary significantly (< 0.2 % absolute).
Difficult matrices
Organic substances
Samples hard to digest (crackable) may be digested by hyrogen containing, carbon containing and/or
chlorine containing additives like graphite, polyethylene, hexamethylentetramine or NH4Cl .
The additives must be dry and must not contain any oxygen.
Substances containing fluorine
Substances containing fluorine react with the quartz glass forming silicon tetrafluoride and discharge
oxygen which will be measured as CO.
Additives, containing blank values
Partially, the recommended additives are hygroscopic and therefore they will deliver a oxygen blank
value.
This blank value has to be determined in order to be able to correct the analysis results.
Procedure example:
6 x analysis of 15 - 16 mg additive.
If the results are stable, compute the mean value from samples 4, 5 and 6 and then subtract this
value from all samples which have been weighed in with an additive. (Input in column "Blank")
Measuring alkaline/earth alkaline samples
When measuring alkaline/earth alkaline samples the pyrolysis tube will corrode and its lifetime will be
shortened.
The system pressure will bloat the tube until it eventually bursts.
This may lead to destruction of the furnace.
It is recommended to check the tube regulary for bloatings and to replace it in time with original spare
parts.
Notes on matrix dependency
Due to the nature of pyrolysis, differences in recovery may occur, depending on the molecular
structure and bond type of the oxygen. This fact has to be considered when very precise
measurements are required.
To guarantee the absolute accuracy of the measuring results, it is recommended to use standard
substances for calibration and daily factor determination which have the same bond type like oxygen.
For general measurements of unknown substances use the average daily factor of 2 measured
standards.
Variants Operating Instructions vario EL cube ©Elementar Analysensysteme GmbH
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