Metrohm 850 Professional IC Anion MCS Prep 3 - Manual (Page 100)

4.8 Rinsing the sample path
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850 Professional IC –Anion – MCS – Prep 3
2 Aspirating the sample and measuring time
Aspirate a sample typical for the later application and use a stop
watch to measure the time required by the sample to travel from the
sample vessel to the end of the sample loop.
The time measured corresponds to the "transfer time". The rinsing
time should be at least 3 times the transfer time.
Checking the rinsing time
It is possible to determine whether the rinsing time is adequate via a direct
measurement of the sample carry-over. Proceed as follows:
1 Preparing two samples
￭ Sample A: A typical sample for the application.
￭ Sample B: Ultra pure water.
2 Determining "Sample A"
Let "Sample A" pass through the sample path for the duration of the
rinsing time, then inject and measure.
3 Determining "Sample B"
Let "Sample B" pass through the sample path for the duration of the
rinsing time, then inject and measure.
4 Calculating sample carry-over
The degree of the sample carry-over corresponds to the ratio of the
peak areas of the measurement for sample B to the measurement for
sample A. The lower the ratio, the lower the sample carry-over. This
ratio can be altered by varying the rinsing time – thus allowing the
rinsing time required for the application to be ascertained.