Metrohm 942 Extension Module Vario Manual page 57

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942 Extension Module Vario ONE/Deg (2.942.1060)
2 Aspirating the sample and measuring the time
Aspirate a sample typical for the later application and use a stop-
watch to measure the time the sample needs to go from the sample
vessel to the end of the sample loop.
The time upon stopping the watch corresponds to the "transfer
time". The rinsing time should be at least three times the transfer
time.
Checking the rinsing time
You can also determine if the applied rinsing time is sufficient by measur-
ing the sample carry-over directly. Proceed as follows to do this:
1 Preparing two samples
Sample A: A typical sample for the application.
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Sample B: Ultrapure water.
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2 Determining "Sample A"
Allow "Sample A" to run through the sample path for the duration of
the rinsing time; inject and then measure it.
3 Determining "Sample B"
Allow "Sample B" to run through the sample path for the duration of
the rinsing time; inject and then measure it.
4 Calculating the sample carry-over
The extent of sample carry-over corresponds to the ratio of the peak
areas of the measurement from Sample B to the measurement from
Sample A. This ratio can be modified by varying the rinsing time,
allowing you to determine the rinsing time required for the applica-
tion.
5 Operation and maintenance
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