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

(1)气体分析仪的组装与初步试验将四个单元串联组装成一种新型的水中温室气体分析仪。它们是一个吹扫和捕集装置，一个气相色谱仪，一个检测器和一个数据处理器。作为数据处理器，我们使用日本岛津株式会社的chroopak。吹扫和疏水装置由气体吹扫瓶、冷阱和体积测量管组成。用于气体分离的气相色谱仪包含一个气体分离柱和一个控制柱温度的控制器，温度范围从40到100个色谱柱。氮气被用作载气而不是纯空气，因为氮气在分离气体成分方面效率更高。该探测器是安装在热控铝块中的半导体探测器。根据初步测试数据，将探测器温度设置为42‰。氧气入口和气体混合管连接在探测器上。(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。该分析仪的灵敏度足以测定溶解在淡水或海水样品中的氢、一氧化碳和甲烷的原位浓度。实验还表明，该分析仪适用于高浓度硫化氢的检测。然而，灵敏度太低，无法检测到原位浓度的一氧化二氮。

(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.