Trial manufacture of an analyzer with a semiconductor detector for greenhouse gases in water

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(1) Assembling and preliminary tests of a gas analyzerA new analyzer for greenhouse gases in water was assembled by connecting four units in a series. They are a purge and trap unit, a gas chromatograph, a detector, and a data processor. As a data processor, we use Chromatopak of Shimadzu Co. Ltd., Japan. The purge and trap unit is consisted of a gas-purging bottle, a cold-trap, and a volume-measuring tube. The gas chromatograph for gas separation contains a gas-separation column and a controller of the column temperature within a range from 40 to 100ﾟC.Nitrogen is used as a carrier gas instead of pure air because of a higher efficiency of nitrogen in separating gas constituents. The detector is a semi-conductor detector installed in an aluminum block which is thermally controlled. The detector temperature is set at 42ﾟC based on the data obtained by preliminary tests. An oxygen inlet and a gas mixing tube is attached to the detector.(2) Field tests of the gas analyzerThe availability of the analyzer was tested at Lake Kizaki and Mikawa Bay. The analyzer showed sensitivity enough to determine in situ concentrations fo hydrogen, carbon monoxide and methane dissolved in fresh-or sea-water samples. It is also shown that the analyzer is useful for hydrogen sulfide at high concentrations. However, the sensitivity was too low to detect nitrous oxide at in situ concentrations.