| Many of our customers
would like to determine the moisture content of their
gases. Metrohm has now developed a clever method based
on the ISO standard 10101: «Natural gas:
Determination of water by the Karl Fischer method».
The reproducible determination
of the water content is tricky as many gases
usually only contain a few µg/L water. The problem
is not the coulometric measurement itself, but the sample
introduction. An optimal measuring setup and the exact
determination of the gas volume are the be-all and end-all
of water determination in the lower ppm range.
In order to ensure a reproducible gas
introduction time, the control of the valves should
be automated. The tiamo™
titration software is also extremely suitable for
this purpose: by using a relay box, the valves can be
opened and closed according to the conditioning or determination
status of the coulometer. In addition, the duration
of the gas introduction is documented and can be used
for calculating the gas volume.
The gas to be analyzed is passed through
the Karl Fischer titration cell in which the water is
absorbed by the KF reagent and then determined using
Metrohm’s 831
KF Coulometer. In addition to natural gas, the Metrohm
method can also be used for other gases (e.g. nitrogen)
that do not react with the Karl Fischer reagent.
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