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

(1)气体分析仪的组装和初步测试一种新型的水中温室气体分析仪是由四个单元串联而成的。它们是吹扫和捕集装置、气相色谱仪、检测器和数据处理器。作为数据处理器，我们使用Shimadzu Co. Ltd.的Chromatopak，日本吹扫捕集装置由吹扫瓶、冷阱和体积测量管组成。用于气体分离的气相色谱仪包括气体分离柱和将柱温控制在40至100 ℃范围内的控制器。由于氮气在分离气体成分中的效率更高，因此氮气代替纯空气用作载气。探测器是安装在热控制铝块中的半导体探测器。根据初步测试获得的数据，将检测器温度设定为42 ° C。氧气入口和气体混合管连接到检测器。(2)气体分析仪的现场测试在木崎湖和三川湾测试了分析仪的可用性。该分析仪显示出足够的灵敏度，以确定在现场浓度的氢，一氧化碳和甲烷溶解在淡水或海水样品。它还表明，该分析仪是有用的硫化氢在高浓度。然而，灵敏度太低，无法在原位浓度下检测一氧化二氮。

(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.