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Abstract:
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A portable gas chromatograph, using a single flame ionization
detector, was constructed. The unit was tested for response to
surge, sway and heave accelerations up to 0.3g. Also the detector's
response was studied for roll and pitch up to 25 degrees with
periods ranging from 3 to 20 seconds. The effect on the detector's
response of variation in hydrocarbon concentrations in the parts
per million range was investigated and response increased with increasing
concentration. Samples containing 1, 10, 100, 1000, and
10,000 parts per million dodecane were analyzed, and under the higher
accelerations trace distortion was evident for concentrations below
10 parts per million. Stationary isothermal chromatograms of a
normal alkane sample (nC6 - nC32) were compared with those obtained
under the various test conditions and no detectable difference in
peak area (which represented approximately 1 microgram of the
particular hydrocarbon) or retention time was evident. The limits
of detection for the Aerograph detector were found to be 21.8 x 10-6
mg/sec for a 30 degree roll, 29.1 x 10-6mg/sec for 20 degree pitching and 21.8 x 10-6 mg/sec for a 0.6g heave acceleration. For the
range of translational and angular accelerations that might be expected
on a platform at sea, it was found that medium resolution
gas chromatography using a flame ionization detector can be conducted,
but in the trace analysis region, trace distortion can be
expected. |