Metrohm 784KFP User Manual

Mertrohm AG CH-9101 Herisau/Switzerland Phone +41 71 353 85 85 Fax +41 71 353 89 01 Internet www.metrohm.ch E-Mail info@metrohm.ch

784 KFP Titrino

Instructions for Use

8.784.1003 99.08 / sn

Table of contents

1 Overview...................................................................................................................2

2 Manual operation .....................................................................................................6

2.1 Keypad ......................................................................................................................... 6

2.2 Principle of data input .................................................................................................. 7

2.3 Text input ...................................................................................................................... 8

2.4 Configuration, key <CONFIG>................................................................................... 9

2.5 Key <MODE> ........................................................................................................... 14

2.6 Parameters, key <PARAM> ..................................................................................... 15

2.6.1 Parameters for KFT ............................................................................................. 15

2.7 Result calculations ..................................................................................................... 25

2.8 Statistics calculation................................................................................................... 28

2.9 Common variables ..................................................................................................... 30

2.10 Data output............................................................................................................... 31

2.10.1 Reports for the output at the end of a determination....................................... 31

2.10.2 Display of the Curve .......................................................................................... 33

2.11 User name, key <USER> ....................................................................................... 34

2.12 Method memory key <USER METH>.................................................................... 35

2.13 Current sample data, key <SMPL DATA> ............................................................. 37

2.14 Silo memory for sample data................................................................................... 38

2.15 Storing determination results and silo calculations ................................................ 41

2.15.1 Storing determination results ............................................................................ 41

2.15.2 Silo calculations................................................................................................. 42

2.16 Manual dosing.......................................................................................................... 44

3 Operation via RS232 Interface ..............................................................................45

3.1 General rules .............................................................................................................. 45

3.1.1 Call up of objects................................................................................................. 46

3.1.2 Triggers................................................................................................................ 47

3.1.3 Status messages................................................................................................. 48

3.1.4 Error messages ................................................................................................... 49

3.2 Remote control commands ....................................................................................... 52

3.2.1 Overview .............................................................................................................. 52

3.2.2 Description of the remote control commands.................................................... 67

3.3 Properties of the RS 232 Interface............................................................................. 90

3.3.1 Handshake .......................................................................................................... 90

3.3.2 Pin Assignment.................................................................................................... 93

3.3.3 What can you do if the data transfer does not work?......................................... 95

4 Error messages and Troubleshooting.................................................................. 97

4.1 Error and special messages ...................................................................................... 97

4.2 Diagnosis.................................................................................................................. 100

4.2.1 General .............................................................................................................. 100

4.2.2 Procedure .......................................................................................................... 100

4.2.3 Equipment required:.......................................................................................... 101

4.2.4 Diagnosis steps................................................................................................. 101

4.3 Initialize and test RAM.............................................................................................. 110

4.4 Releasing a locked spindle...................................................................................... 111

784 KFP Titrino

Table of contents

5 Preparations......................................................................................................... 112

5.1 Setting up and connecting the instruments ............................................................ 112

5.1.1 Titrino with Stirrer or Titration Stand .................................................................. 112

5.1.2 Connection of a printer...................................................................................... 113

5.1.3 Connection of a balance ................................................................................... 114

5.1.4 Connection of a KF Oven.................................................................................. 115

5.1.5 Connection of a Sample Changer .................................................................... 116

5.1.6 Connection of the 774 Oven Sample Processor .............................................. 117

5.1.7 Connection of a computer................................................................................. 118

5.1.8 Connection of a Remote Box ............................................................................ 118

5.2 Connection of electrodes and preparing titration vessel ........................................ 122

6 Appendix ..............................................................................................................123

6.1 Technical specifications........................................................................................... 123

6.2 Pin assignment of the "Remote" socket................................................................... 125

6.2.1 Lines of the "Remote" socket during the titration.............................................. 127

6.2.2 Possible configurations of the activate pulse KFT ........................................... 128

6.3 User methods ........................................................................................................... 129

6.3.1 General............................................................................................................... 129

6.3.2 KF Titer determination with H2O or methanol standard "H2OTiter".................. 130

6.3.3 KF Titer determination with sodium tartrate "TarTiter" ...................................... 131

6.3.4 Blank determination for KFT "Blank_KF"........................................................... 132

6.3.5 KF-titration with blank value subtraction "KF-Blank"......................................... 133

6.3.6 KF-titration without blank value subtraction "KF".............................................. 135

6.3.7 KF titrations with various KF reagents .............................................................. 137

6.3.8Determination of the bromine number "BrNumber"........................................... 138

6.4 Titrino validation........................................................................................................ 139

6.4.1 Electronic tests .................................................................................................. 139

6.4.2 Wet tests ............................................................................................................ 139

6.4.3 Maintenance and adjustment of the Titrino ...................................................... 139

6.5 Warranty and certificates.......................................................................................... 140

6.5.1 Warranty............................................................................................................. 140

6.5.2 Certificate of Conformity and System Validation .............................................. 141

6.6 Scope of delivery and ordering designations.......................................................... 143

Index ........................................................................................................................147

784 KFP Titrino

Overview

784 KFP Titrino

Instructions for Use

784 KFP Titrino

Overview

1 Overview

Front view of instrument:

784 KFP Titrino

1 Exchange Unit

2 Display

3 Control keys and indicator lamps on the Titrino

Key < > Power switch

Key < 4 > Switching stirrer ON/OFF

Key <DOS> Dosing key. Dispensing is performed as long as

<DOS> is being pressed. Used e.g. to prepare the Exchange Unit. The dispensing rate can be set with potentiometer (5).

Key <STOP/FILL> - Stops procedures, e.g. titrations, conditioning.

- Filling after manual dosing with <DOS>.

Key <START> Starts procedures, e.g. titrations, conditioning.

Identical with key <START> of the separate

keypad. Indicator lamps: "COND." Lamp flashes when conditioning is performed

and the titration vessel is still wet. It is on if con-

ditioning is ok. "STATISTICS" Lamp is on when the "statistics" function

(calculation of mean and standard deviation) is

on. "SILO" Lamp is on when silo memory (for sample data)

is on.

Overview

4 Setting of display contrast

5 Controls the dosing rate during manual dosing with <DOS> and

subsequent filling

784 KFP Titrino

Overview

Rear view of instrument:

RS 232

Keyboard

Remote

Pol

1.784 Nr.

100 - 240 V

f = 50 - 60 Hz

S = 15 W

Made by Metrohm Herisau Switzerland

784 KFP Titrino

6 RS232 interfaces

2 separate interfaces for the connection of printer, balance, and computer

7 Remote lines (input/output)

for the connection of the Remote Box, Sample Changers, robots etc.

8 Connection of electrodes

• 1 measuring input for polarized electrodes, e.g. KF electrode

9 Connection for separate keypad

10 Connection for power cable

With power supplies where the voltage is subject to severe HF disturbances, the Titrino should be operated via an additional power filter, e.g. Metrohm 615 model.

Overview

11 Connection for stirrer

728 Magnetic Stirrer, 722 Rod Stirrer, 703 or 727 Ti Stand

Supply voltage: 10 VDC (I ≤ 200 mA)

12 Rating plate

with fabrication, series and instrument number

784 KFP Titrino

2.1 Keypad

SILO

–9STATISTICS

MEAS/HOLD

→↑←

↓

STOP

START

/6*

USER METH

)3DEF

(2C-FMLA

MODE

REPORTS

USER

CURVE

2 Manual operation

2.1 Keypad

PARAMCONFIG

SMPL DATA

PARAM Parameters.

SMPL DATA Sample data.

CONFIG Configuration.

STATISTICS ON/OFF switching of statistics calcu-

lations of consecutive determination, see page 28.

MEAS/HOLD ON/OFF switching of measurements

between titrations and hold during titrations.

SILO ON/OFF switching of silo memory for

C-FMLA Calculation values, see page 27.

sample data, see page 38.

DEF Formulas, data output, see page 25ff.

ABC

;

–

USER METH Management of internal method mem-

ory, see page 35.

PRINT Printing of reports, see page 33.

REPORTS Result output.

MODE Mode dialogue, see page 14.

USER User name, see page 34.

CLEAR ENTER

CURVE Switching result/curve display, see

page 33.

←,→ Selection of special values (dialog

marked with ":").

QUIT

↑,↓ Cursor key for navigation.

CLEAR Clears values, set special values.

6.2130.050

ENTER Stores values.

STOP Stops methods.

QUIT Quits inquiries, waiting times, printing.

START Starts methods.

The third functions (inscriptions in the triangle) on the keys of the keypad are used for formula entry, see page 25.

784 KFP Titrino

2.2 Principle of data input

remo

te box: OF

• If you press a key, you will find a group of inquiries

in the display.

configuration >monitoring >peripheral units >auxiliaries >RS232 settings COM1 >RS232 settings COM2 >common variables

configuration >peripheral units send to COM1: IBM send to COM2: IBM man.reports to COM: 1 balance: Sartorius stirrer control: OFF

configuration >monitoring >peripheral units >auxiliaries >RS232 settings COM1 >RS232 settings COM2 >common variables

Example key <CONFIG>:

In the first line you see where you are: You pressed

key <CONFIG> and you are now in the inquiries "configuration".

• The cursor is inverted. In our example the cursor is

on the inquiry ">monitoring". You can move the cur-

sor up and down with keys <↑> and <↓>.

• If a dialog text is marked with ">", it contains a

group of inquiries itself. You go to this group pressing <ENTER>. Example inquiries of "peripheral units":

The first two lines indicate again where you are.

Then you find the inquiries. If a dialog text of an inquiry is marked with ":", you

can select a value with keys <←> and <→>

(forward/backward).

• A value is stored with <ENTER> and the cursor

moves to the next inquiry.

• With key <QUIT> you move one level up, in our ex-

ample you go back to ">peripheral units".

If you press <QUIT> once more, you quit the in-

quiries in "configuration" altogether.

• If you can scroll, "↓" or "↑" appear in the right lower

or upper corner of the display.

2.2 Principle of data input

784 KFP Titrino

2.3 Text input

REPORTS

2.3 Text input

Example storing a method:

user methods >store method method name: ********

<CLEAR>

ABC

user methods >store method: method name:

ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz µ°!"#$&'()*+,-./ 0123456789

<QUIT>

user methods >store method method name: Text

<ENTER>

• Press key <USER METH>.

Place the cursor to ">store method" and press <ENTER>. The name of the method which is currently in the working memory is displayed.

• Delete this name with <CLEAR>.

• Open the "text writing mode" with key <ABC>.

You can now select the desired character by means of the cursor keys, then confirm this character. Select the next character... When you confirmed the last character, i.e. your name is complete, you quit the text writing mode with <QUIT>. Confirm now the name with <ENTER>.

• During text input you can correct typing errors with

<CLEAR>: <CLEAR> deletes the characters one by one.

• If you wish to modify an existing name, do not de-

lete the existing name before you start the text input mode. Proceed then as follows:

1. Press <USER METH>, place the cursor to ">store method" and press <ENTER>.

2. Open the text writing mode directly: Press key <ABC>.

3. <CLEAR> now deletes the characters one by one or you can add additional characters.

4. If your text is complete, leave the text writing mode with <QUIT> and confirm the text with <ENTER>.

784 KFP Titrino

2.4 Configuration, key <CONFIG>

Key <CONFIG> serves to enter device specific data.

CONFIG

configuration >monitoring >peripheral units >auxiliaries >RS232 settings COM1 >RS232 settings COM2 >common variables

The set values apply to all modes.

monitoring:

Monitoring of instrument validation, service interval and printout of diagnostic report.

peripheral units:

Selection of printer, balance, stirrer control and COM for manual report output.

auxiliaries:

e.g. setting of dialog language, date, time, type of result display.

RS232 settings COM1 and 2:

RS parameters for the COM's.

common variables:

Values of common variables.

2.4 Configuration, key <CONFIG>

>monitoring

validation: OFF

time interval 365 d

time counter 0 d

service: OFF

The display texts of the Titrino are shown on the left side. The values are the default values.

Monitoring functions

Monitoring the validation interval (ON, OFF)

Monitoring is carried out at the end of the titrations and when the Titrino is switched on. If the monitoring responds the message "validate instrument" appears. The message vanishes with <CLEAR>. At the same time the counter is reset to zero.

If "ON" has been set:

Time interval for validation (1...9999 d)

see also page 90 Identical for COM2.

Baud rate (300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200)

Data bit (7, 8)

Stop bit (1, 2)

Parity (even, odd, none)

Handshake (HWs, SWline, SWchar, none)

see page 90.

Values of the common variables

Common variables C30...C39 (0.. ± 999999)

The values of all common variables are displayed. For creating common variables see page 30.

Settings with key <CONFIG> and power ON

Proceed as follows:

1. Switch the Titrino OFF.

2. Press <CONFIG> and keep it pressed during switching the Titrino ON. The display shows the following:

Setup >lock >curve

lock:

Locking keys <CONFIG>, <PARAM> and <SMPL DATA>, and the functions "recall method", "store method" and "delete method" of the internal method memory in the Titrino.

curve:

Changes the appearance of the curve printout.

>lock

lock

"ON" means that the corresponding function is not accessible anymore.

<configuration>: OFF

<parameters>: OFF <smpl data>: OFF

recall method: OFF store method: OFF delete method: OFF

The corresponding key is locked.

The corresponding function in the internal method memory of the Titrino is locked.

784 KFP Titrino

2.4 Configuration, key <CONFIG>

>curve

grid: ON

frame: ON

scaling: Full

width 0.5

length 0.05

curve

The settings are valid for COM1 and COM2. If you change the printer type, the following settings are initialized according to the printer.

Grid drawing (ON, OFF)

Frame drawing (ON, OFF)

Type of scaling (Full, Auto)

Full: The scaling goes from the greatest to the smallest value. auto: The scaling from tick to tick, e.g. the smallest/greatest values lie in between the first/last tick.

Width (0.2...1.00)

1 is greatest width. If you set 1, you may loose the label at the right margin.

Length (0.01...1.00) Time axis:

Curve length

0.01 100 cm

0.1 10 cm

0.5 2 cm 1 1 cm

784 KFP Titrino

2.5 Key <MODE>

MODE

2.5 Key <MODE>

;

–

mode mode: KFT measured quantity: Ipol

With the key <MODE> the dialogue „mode“ is opened.

The 784 Titrino is a titrator, specially designed for Karl Fischer water determinations. It has exclusively the mode KFT (Karl Fischer Titration).

With <ENTER> the selection of the measured

quantity is activated. Select Ipol or Upol with <←> or <→> and confirm it also with <enter>.

The following modes can be selected:

• KFT: Karl Fischer Titration, the determination of

water content.

The mode KFT is equipped with a set of standard parameters. They only need few settings in order to be ready to work.

784 KFP Titrino

2.6 Parameters, key <PARAM>

The key <PARAM> is used for the entry of values that

PARAM

2.6.1 Parameters for KFT

determine the modes. Values marked with "cond." are accessible during the conditioning in the KFT mode. "**titr." means that these values can be changed during the titration. They influence the ongoing determination. Other values can only be changed in the inactive state. The display texts of the Titrino are shown on the left side. The values are the default values.

2.6 Parameters, key <PARAM>

parameters >control parameters >titration parameters >stop conditions >statistics >preselections

>control parameters

EP at U 250 mV cond.

dynamics 100 mV **titr.

control parameters:

for the EP.

titration parameters

control the general course of the titration.

stop conditions:

Parameters for the termination of the titration.

statistics:

Calculation of mean values and standard deviation, see page 28.

preselections:

ON/OFF of various auxiliary functions such as automatic requests after the start and activate pulse.

Control parameters

Endpoint (input range depending on the measured quantity: U, Ipol: 0.. ±2000 mV

I, Upol: 0...±200.0 µA)

Control (input range depends on the measured quantity: U, Ipol: 1...2000 mV

I, Upol: 0.1...200.0 µA)

Outside of the control range: constant dosing, see page 21.

784 KFP Titrino

2.6 Parameters, key <PARAM>

max.rate max. ml/min **titr.

min.volume incr. min. µl **titr.

stop crit: drift **titr. stop drift 20 µl/min **titr.

t(delay) 10 s **titr.

Maximum dosing rate (0.01...150 mL/min, max.)

<CLEAR> sets "max.". This parameter determines primarily the addition rate outside the control range, see page 21. The maximum rate depends on the Exchange Unit: Exchange Unit max. rate

5 mL 15 mL/min 10 mL 30 mL/min 20 mL 60 mL/min 50 mL 150 mL/min

Minimum volume increment (0.1...9.9 µL, min.)

<CLEAR> sets "min.". This parameter determines the addition rate at the start and the end of the titration, see also page 21. This parameter influences the titration speed and therefore its accuracy very strongly: A smaller "min.volume incr." results in a slower titration.

Type of stop criteria (drift, time)

Titration stops, if EP and stop drift are reached

(1...999 µL/min)

Titration stops if there is no dosing during t(delay) (0...999 s, INF)

<CLEAR> sets "INF". Switch off when EP is reached and the set time after the last dosing has elapsed.

stop time OFF s **titr.

>titration parameters

titr.direction: –

pause 1 0 s **titr.

If t(delay) is "INF"

Stop after a time (0...999999 s, OFF)

<CLEAR> sets "OFF". Stop after the set time after start of titration. "OFF" means no stop, i.e. titration for an "infinitely" long time.

Titration parameters

Direction is set automatically (+, –, auto)

auto: The direction is set automatically by the Titrino. +: Direction of higher voltage (more "positive"),

larger currents.

– : Direction of lower voltage, smaller currents.

Pause 1 (0...999999 s)

Waiting time before start volume, e.g. for equilibration of the electrode after start. The waiting time can be aborted with <QUIT>.

784 KFP Titrino

2.6 Parameters, key <PARAM>

start V: OFF cond.

start V 0.0 ml cond.

factor 0 cond.

dos.rate max. ml/min **titr.

pause 2 0 s **titr.

Type of start volume (OFF, abs., rel.)

"OFF": start volume switched off "abs.": absolute start volume in mL "rel.": relative start volume to sample size.

If "abs." is set:

Absolute start volume (0...999.99 mL)

If "rel." is set:

Factor for relative start volume (0...±999999).

Calculated as: start V in mL = factor ∗ sample size

Dosing rate for start volume (0.01...150 mL/min, max.)

<CLEAR> sets "max.". The maximum rate depends on the Exchange Unit: Exchange Unit max. rate

5 mL 15 mL/min 10 mL 30 mL/min 20 mL 60 mL/min 50 mL 150 mL/min

Pause 2 (0...999999 s)

Waiting time after start volume, e.g. reaction time after dosing of a start volume. The waiting time can be aborted with <QUIT>.

extr.time 0 s **titr.

I(pol) 50 µA

U(pol) 400 mV

electrode test: OFF

temperature 25.0 °C cond.

time interval 2 s cond.

Extraction time (0...999999 s)

During this time the titration is running. It will not be stopped (also if EP is already reached), before the extraction time is terminated. The extraction time can be aborted with <QUIT>.

Polarization current (–127...127 µA)

or the

polarization potential (–1270...1270 mV, in steps of 10 mV) is inquired.

Electrode test (OFF, ON)

Test for polarized electrodes. Performed on changeover from the inactive standby state to a measurement. "OFF" means that the test is not performed.

Titration temperature (–170.0...500.0 °C).

The temperature can be entered manually.

Time interval (1...999999 s)

Time interval for acquisition of a measured value into the measuring point list.

784 KFP Titrino

2.6 Parameters, key <PARAM>

>stop conditions

stop V: abs. **titr.

stop V 99.99 ml **titr.

factor 999999 **titr.

filling rate max. ml/min **titr.

Stop conditions for titration

If this is not "normal", i.e. after reaching the EP

Type of stop volume (abs., rel., OFF)

"abs.": absolute stop volume in mL "rel.": relative stop volume to sample size "OFF": stop volume switched off. Stop volume is not

monitored. The stop volume applies for one single titration. The conditioning volume is not monitored.

If "abs." is set:

Absolute stop volume (0...9999.99 mL)

If "rel." is set:

Factor for relative stop volume (0...±999999)

Calculated as: Stop V in mL = factor ∗ sample size

Filling rate after titration (0.01...150 mL/min, max.)

<CLEAR> sets "max.". The maximum rate depends on the Exchange Unit: Exchange Unit max. rate

5 mL 15 mL/min 10 mL 30 mL/min 20 mL 60 mL/min 50 mL 150 mL/min

>preselections

conditioning: ON

display drift: ON cond.

drift corr: OFF cond.

drift value 0.0 µl/min cond.

req.ident: OFF cond.

Preselections for the sequence

Automatic conditioning of titration vessel (ON, OFF)

If conditioning is "ON", the solution is constantly kept at the endpoint. When conditioning is performed, the volume drift can be displayed during the conditioning:

Display of drift during conditioning (ON, OFF).

Volume drift.

Type of drift correction (auto, man., OFF)

Type of drift correction: (EP – drift ∗ time)

auto: drift value at start is valid man.: see below OFF : no correction

Value for manual drift correction (0.0...99.9 µL/min)

Request of identifications after start of titration (id1, id1&2, all, OFF)

After start, sample identifications can be requested automatically: Only id1, id1 & id2, all three id's or no inquiries.

784 KFP Titrino

2.6 Parameters, key <PARAM>

req.smpl size: OFF cond.

limit smpl size: OFF cond.

low lim. 0.0 cond. up lim. 999999 cond.

oven: no cond.

Request of sample size after start of titration (value, unit, all, OFF)

"all" the value and the unit will be requested.

Limiting value check for sample size (ON, OFF)

With "ON" the error message "sample size out." appears if the entry is outside the set limits. The limiting values are shown in the display window. The absolute value of the limit is checked during sample size input and during the calculation of the results.

If "ON" has been set:

Lower limit for sample size (0.0...999 999)

Upper limit for sample size (0.0...999 999)

Connected oven (COM1, COM2, no)

COM of the Titrino to which the oven is connected. If an oven is connected via RS232 an inquiry will be made for the oven results and these will be inserted into the result report of the Titrino. The report output on the oven must be switched OFF (see also page 115). Set "no" if no oven has been connected or if you have not connected the oven to Titrino the via RS232 interface.

activate pulse: OFF cond.

Pulse output on I/O line L6 (L6, pin 1) of the remote socket (first, all, cond., OFF) e.g. start of a Dosimat,

see page 126.

784 KFP Titrino

2.6 Parameters, key <PARAM>

<START>

(Sta

rt delay)

(Sta

rt conditions)

Calculation

sData output

(Reconditioning)

(Stirrer OFF

)

Titration sequence of KFT

(Activate pulse)

(Stirrer ON)

(Preconditioning)

(<START>

(Activate pulse)

(Start delay)

(Request ident.)

(Request smpl size)

(Extraction time)

Titration with test of

stop criterion

After the start, the activate pulse is outputted and the stirrer switched on.

The start delay time is waited off.

If conditioning is on, the sample solution is titrated until the EP is reached. The display shows then

drift OK 2.3 µl/min

KFT conditioning

The vessel is now conditioned. The titration can be started with <START>.

The sample identifications and the sample size are requested.

Pause 1 is waited off, the start volume is dispensed and pause 2 waited off.

The titration is executed. If the extraction time is not yet over when the endpoint has been reached, the titration will only be terminated after the extraction time is over.

The stirrer is switched off when there is no conditioning.

Calculations are carried out.

Data are outputted.

Conditioning is carried out.

784 KFP Titrino

2.6 Parameters, key <PARAM>

Control parameters for KFT

The control parameters can be set according to your samples. The default parameters are already set to get satisfactory results. Optimize the control parameters for specific samples only.

During the titration, reagent dosing is carried out in 3 phases:

U/mV

t/s

Initial

dosing

I/uA

KFT Ipol

Continuous

dosing

Control

range

V/mL

1. Initial dosing: Here the dosing rate increases constantly up to "max.rate".

2. Continuous dosing: Dosing is performed at the maximum rate "max.rate" until the control range (dynamics) is reached.

3. Control range (dynamics): In this range, dosing is performed in single steps. The last dosing steps are controlled by the parameter "min.volume incr.".

KFT Upol

V/mL

Remarks:

• Titer determination should have the same modes and the same parameters as the

sample titrations.

• In most cases the preset default parameters provide precise and reproducible results.

• Ipol gives relatively steep curves. They are flatter with Upol.

784 KFP Titrino

2.6 Parameters, key <PARAM>

Mechanisms of the KFT parameters in Ipol mode

U/mV

Titration

(direct titration)

EP at U

Titration (Back titration)

I(pol)

Excess H2O

Excess Iodine-

darker solution

I/µA

• The position and curve characteristics of the line between the ranges of excess water

or excess iodine depends on the type of sample and the ingredients of the working media.

• The endpoint has to be set close to the range margin, but always within the iodine

excess range. If the endpoint is set too close to the limit, an overdose of KF reagent may be dispensed. The steeper the curve at the preset polarization current I(pol), the more delicate it is to titrate to a steady and reproducible endpoint. For the titration of troublesome samples, the particular conditions must be optimized by trial and error. Always mind the color of the working medium at the end point as your guideline. Remark: In most cases the preset default parameters provide precise and reproducible results.

• If you select negative values for a parameter, you should choose negative values for all

other parameters too in order to have compatible parameter sets.

• In KFT Upol mode, all parameters work in a similar manner as in KFT Ipol mode.

784 KFP Titrino

2.6 Parameters, key <PARAM>

The determination of the free water is easily done, as far as the specifications of the reagent manufacturer regarding the "water capacity" of the reagents are considered. Problems may occur with specific sample matrices. The relevant literature contains many precise analysis instructions. Here, we give you some useful hints for the sample addition.

Sample addition

For sample addition various accessories are available, for example injection syringes, weighing spoons etc.

It is a good idea to apply the back-weighing technique, except when you are disposing small amounts of liquids with a micro-syringe. Fill the syringe or the weighing spoon with your sample just before the titration (e.g. during conditioning) and tare it on a balance with an appropriate precision, which ideally is connected to the Titrino. Sample size request should always be switched on (see page 19). Add the sample during the request for the sample size, and weigh the syringe or weighing spoon again to evaluate the weight difference. Use the transfer of balance data to enter the correct sample size if possible. The weight has to be transmitted in gram. If you transfer the sample size from the balance, the sample size request is confirmed automatically, and the titration is started at once. Otherwise use the keypad to enter the weight.

If the sample size request is switched off, and preconditioning is set, you are explicitly prompted to add your sample. For six seconds, the message "add sample" is displayed after which the titration is started by the Titrino itself. This waiting time can be extended by pressing <MEAS/HOLD>.

Solid samples

Use the glass weighing spoon 6.2412.000 and dispose the sample through the opening for the septum stopper.

Liquid samples

Use a disposable syringe (2...20 mL) or a micro-syringe with a long needle attached. Puncture the septum and dispose the sample carefully. When using disposable syringes, add the liquid sample carefully without dipping into the solvent. Draw back the last drop of sample into the syringe before you redraw the needle. For disposing an exact, small volume of liquid sample, use a micro-syringe. Proceed as described above, but dip the needle into the preconditioned solvent and dispose the sample carefully. Here drawing back of solvent or sample adhering to the needle is not recommended. Always keep in mind to exchange the septum as soon as it shows any large punctures impairing the tightness of the titration cell.

Pasty, viscous samples

For samples which cannot be disposed with a needle because of their high viscosity, you can handle your samples with disposable syringes with a large volume without using a needle. Dispose your sample through the opening of the septum stopper. Back-weigh the syringe after addition of the sample. Be sure to wipe off any adhering excess sample substance of the syringe before taring it.

In any case, pay attention to prevent the penetration of atmospheric moisture into the titration vessel when you are disposing the sample. If you still have to open the titration cell for any reason, determine a blank value and take it into account for the calculation of the titration result (see page 132).

784 KFP Titrino

2.6 Parameters, key <PARAM>

In the following table we attempt to show you solutions related more to the instrument's side:

What to do if ...

Problem Possible causes and remedial action

Dosing at end too long and increments too small. "Is never finished!"

The increments at the end of the titration are too large. "Overshoots".

Solution becomes too brown at the end of the titration.

Solution becomes darker with every titration.

• Increase "min.volume incr.".

• Change stop criterion. Try to increase stop drift or

use a short stopping time as stop criterion, e.g.

• For problematic samples change solvents with

ketones or aldehydes in 2-methoxyethanol or with amines mixture in methanol/glacial acetic, e.g., see literature.

• Lower "max.rate". The following experiment gives you

a reference point for the optimum max.rate: Drift display during conditioning and add sample without starting the titration. Select a value below the maximum drift as "max.rate".

• Optimize setup of electrode and buret tip and

improve stirring.

• The methanol fraction in the solvent is too low.

Change the solvent.

• Electrode could be coated; wipe off with acetone.

• Renew solvent.

• Electrode could be coated; wipe off with acetone.

The drift increases with every titration.

The endpoint is reached "too rapidly".

The titration times become longer and longer.

• Does your sample evolve water extremely sluggishly?

Work with the KF oven.

• Are acids esterified in your sample? Change solution

more frequently. Increase buffer capacity of the solvent.

• Does your sample contain ketones or aldehydes?

Use special reagents suitable for ketones and aldehydes.

• Reduce "max.rate".

• With 2-component reagents the buffer capacity of the

solvent can be exhausted. Change solution.

• If the drift increases at the same time, see above.

784 KFP Titrino

2.7 Result calculations

Formula entry, key <DEF>

2.7 Result calculations

DEF

def >formula >silo calculations >common variables >report >mean

>formula

RS?

RS1=

RS1=EP1∗C01/C00

(

Key <DEF> contains various inquiries for result calculations and data output. The data of this key are method specific and they are stored in the method memory together with the method.

formula:

Formulas for result calculations.

The display texts of the Titrino are shown on the left side. The values are the default values.

Input of formulas

Enter formula number (1...9)

You can calculate up to 9 results per method. Enter a number 1...9.

Input of formula

Example:

RS1=EP1∗C01/C00

Enter formula by means of 3rd functions of keyboard. Here you will find operands, mathematical operations and parentheses. Operands require a number as an identification. You can use the following operands: EPX: EP's. X = 1...9 RSX: Results which have already been calculated with

previous formulas. X = 1...9

CXX: Calculation constants. XX = 00...45

784 KFP Titrino

Rules:

• Calculation operations are performed in the algebraic hierarchy: ∗ and / before + and –.

• Store formula with <ENTER>.

• Calculation quantities and operands can be deleted

with <CLEAR> one by one.

• To delete a complete formula press <CLEAR>

repeatedly until only RSX remains in the display. Confirm with <ENTER>.

If a formula is stored with <ENTER>, result text, number of decimals, result unit and the settings of the result limit control will be requested:

2.7 Result calculations

RS1 text RS1

Text for result output (up to 8 characters)

Text input see page 8.

RS1 decimal places 2

RS1 unit: %

Number of decimal places for result (0...5)

Selection of result unit (%, ppm, g/L, mg/mL, mol/L, mmol/L, g, mg, mL, mg/pc, s, mL/min, no unit or up to 6 characters).

RS1 limit control: OFF

Limit control for the result (ON, OFF)

The limits are checked each time a result is calculated.

If "ON" has been set:

RS1 low lim. 0.0

RS1 up lim. 0.0

RS1 L13 output: OFF

Lower limit (0.0...999 999) Upper limit (0.0...999 999)

Sets line L13 of the remote socket (OFF, active, pulse)

if the result lies outside the limits.

Enter next formula, e.g. for RS2.

Meaning of the calculation variables CXX:

C00 Sample size, see page 37. C01...C19 Method specific operands, see page 27. They are stored with the

method in the method memory. C21...C23 Sample specific operands, see page 37ff. C26, 27 Mean values from silo calculations, see page 41ff. C30...C39 Common variables. C40 Initial measured value of the sample. C41 End volume. C42 Determination time. C43 Volume drift for KFT with conditioning. C44 Temperature. C45 Dispensed start volume.

784 KFP Titrino

Input of method specific operands C01...C19, key <C-FMLA>

C-FMLA

2.7 Result calculations

With <C-FMLA> the operands C01...C19 can be put in. For the calculation, the operands are used, which were introduced in the formula.

The inputs method specific and are store in method memory.

The calculation report can be printed with the key sequence

<PRINT><←/→> (press keys repeatedly until "calc" appears in the display) <ENTER>.

Example for a calculation report:

'fm

784 KFP Titrino 02134 784.0010

user sn

date 1999-08-15 time 15:01 3

KFT Ipol KF-Blank

>calculations

Water=(EP1-C38)*C39*C01/C00/C02;2;%

Titer=C39;4;mg/ml

Blank=C38;4;ml

C00= 1.0

C01= 0.1

C02= 1

C38= 0.0

C39= 0.0

------------

Calculation report

mode und method name formulas: result name=formula;number of decimal places;result unit

sample size method specific operands

values of the common variables that are used

784 KFP Titrino

+ 123 hidden pages

Metrohm 784KFP User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual