7.3 Coulometer validation, GLP mode
756/831 KF Coulometer, Instructions for Use
134
7.3.2 Wet tests
GLP (Good Laboratory Practice) requires the periodic validation of the analytical instru-
ments. The reproducibility and accuracy of the instruments are checked.
An annual repetition of the procedure appears to be sensible. Depending on the require-
ments a more frequent check may be indicated, e.g. every 3 or 6 months.
The validation interval can be checked by the Coulometer (set under <CONFIG>, moni-
toring). If the interval has elapsed the Coulometer displays the message validate i
nstru-
ment.
The GLP mode can be used in order to carry out the validation. It contains the
appropriate calculation formulas:
1. content = H2O/C01/C00;3;mg/g
2. recovery = RS1/C22;2;
where
C01=1000
C22=id2= content according to the reagent manufacturer in mg/g
The second formula calculates the recovery rate and is therefore a measure of the accu-
racy. The limit control for the second result is switched on and the limits are 0.97...1.03.
These values apply for a 1.00 mg/g standard.
For a 0.10 mg/g standard the limits should be set to 0.90...1.10.
7.3.3 Maintenance and adjustment of the Coulometer
The Coulometer should be serviced and adjusted by Metrohm service at regular intervals.
The Coulometer can check the date of the next service with the help of the monitoring
function "Service" under <CONFIG>, monitoring. If this date has been passed then the
Coulometer will display the message
service is due.
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