Metrohm 6.02729.110, Руководство пользователя

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IC equipment: Inline Ultrafiltration 2 - push mode
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6 Maintenance
6.1 Service life of the filtration membrane
One common problem in filtration is that solid substances in the sample
are deposited on the filtration membrane, causing it to become blocked
over time. This effect is reduced with the following design measures.
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The ultrafiltration cell has a symmetrical design.
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The ultrafiltration cell is placed horizontally in the sample changer.
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The sample flows through the sample chamber of the ultrafiltration
cell. The filtrate is aspirated on the filtration side. In this way, solid sub-
stances adhere less to the membrane.
Monitor the filtration process and replace the filtration membrane if
needed.
A declining recovery rate in standard solution analyses is an indicator for
an imminent blockage of a filtration membrane. Prepare standard solu-
tions ideally with the sample matrix to be analyzed.
If a large number of samples is analyzed, we, at Metrohm, recommend
measuring check standards regularly. In the case of samples with high par-
ticle loads, measure check standards after every 5th to 10th sample. No
general prediction regarding the number of filtration cycles can be made.
Also, the change in the recovery rate may be different with more samples
being analyzed. Whereas the recovery rate with one sample matrix may
remain constant over many samples and then suddenly drop off severely,
its decline may be slow and continuous with a different sample composi-
tion.
At which time a filtration membrane needs to be replaced depends on the
sample matrix and the specifications of the analysis method applied. Expe-
rience has shown that minuscule particles and suspended substances in
the sample matrix will lead to blockage of the filtration membrane faster
than coarser particles will. Coarser particles are more readily propelled
past the membrane in the flow of sample material.
The table Service life of the filtration membrane contains samples that
were filtered with the ultrafiltration cell and a filtration membrane 1
(6.2714.020) with a pore size of 0.2 µm and analyzed on a Metrohm ion
chromatograph.
The listed results were obtained with Inline Ultrafiltration (push mode). The
results are to be seen as examples, not guidelines. Deviating values for the
service life can be found depending on the actual sample matrix.