7 inline sample preparation, 8 rinsing the sample path, Inline sample preparation – Metrohm 850 Professional IC Anion MCS Prep 3 User Manual
Page 99: Rinsing the sample path
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4 Operation and maintenance
850 Professional IC –Anion – MCS – Prep 3
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4.7
Inline sample preparation
To protect the separation column (see Chapter 2.23, Page 68) against for-
eign particles which can affect the separating efficiency, we recommend
that all samples undergo a microfiltration (filter 0.45 µm). The ultrafiltra-
tion cell can be used for filtration (see documentation on the IC Equip-
ment for Ultrafiltration).
Samples containing significant amounts of gas should be degassed. The
sample degasser (see Chapter 2.13, Page 39) (if available) is used for
degassing.
Matrix-loaded samples (e.g. blood, oil) should be prepared for the meas-
urement by means of dialysis (see documentation on the IC Equipment for
Dialysis).
If the concentration of the sample is too high, it should be diluted before
feeding (see documentation on the IC Equipment for Sample Dilution).
For the sample preparation methods Neutralization (replacement of e.g.
Na
+
with H
+
) and cation exchange (replacement of e.g. heavy metals
with H
+
), a sample preparation module (SPM) is used(see Chapter 2.14,
4.8
Rinsing the sample path
Before a new sample can be measured, the sample path must be rinsed
with it so that the measuring result is not falsified by the previous sample
(Sample carry-over).
In the case of automated sample feeding, the rinsing time should be at
least 3 times the transfer time. The transfer time is the time required by
the sample to flow from the sample vessel to the end of the sample loop.
Ascertaining the transfer time
The transfer time depends on the pump capacity of the peristaltic pump,
the total capillary volume and the volume of the gas removed by the sam-
ple degasser (if used) - in other words the amount of gas in the sample.
1 Emptying the sample path
Pump air through the sample path (pump tubing, tubing connec-
tions, capillary in the degasser, sample loop) for several minutes until
all liquid is displaced by the air.