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Finnigan GasBench
Measurement Procedures for Real Samples
II ___________________________________________________________ Introduction
phosphoric acid. A similiar idea leads to DIC measurements. In both cases,
the air in the headspace must be replaced prior to the reaction by He which is
inert and thus will not influence GC analysis.
Measurement timing must take into consideration the times reqired for the
reactions mentioned above as well as the times the autosampler needs to
perform its injections. Nevertheless, one can use only one acquisition script
for all analysis types. If you take care of the reference gas settings in the
method (that is the reference port setting in the Instrument tab and the
reference port switching in the Time Events list), you can use the same
method and sequence for all GasBench II standard work. It is comprehensible
that acqisition script, method and sequence must satisfy the most complicated
of all measurements, i.e. carbonate analysis.
Cleaning Procedure for Sample Vials
The sample vials used for carbonate measurements should be free of organic
and inorganic contaminations before they are loaded with carbonate. To clean
them perform the four steps described below:
1. Fill up the vials with warm diluted phosphoric acid (i.e. phosphoric acid
plus warm distilled water) and leave them for eight hours.
2. Rinse the vials repeatedly with distilled water using a washing bottle.
3. Rinse the vials with acetone using a washing bottle, too. This helps to dry
the vials faster.
4. Dry the vials in a drying chamber at 72 ºC for 2.5 hours. Cover them with
aluminum foil to protect them against contamination.
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