Analytical Sciences

Abstract − Analytical Sciences, 21(4), 421 (2005).

Determination of Trace Water in Gas Samples by an Improved Karl Fischer Coulometer
Huiru DONG, Pengyu BI, Jianping CAO, and Shouyong ZHAO
College of Science, Beijing University of Chemical Technology, Beijing 100029, Peoples Republic of China
The determination of trace water in gas samples, such as isobutene, chloromethane (polymeric staple gases) and SF6 by a conventional Karl Fischer coulometer is very difficult, because of the adsorption of trace water on the surface of sample pipe, the gasification of the liquefied samples, and the migration of moisture into the measuring cell from the surroundings. To solve these problems, we improved a device for coulometric determination of water by Karl Fischer method. The improved coulometer was used to determine the trace water in isobutene, chloromethane and SF6; RSD was less than 5%, and recoveries ranged from 94.1 to 109.1%, which is adequate for the analysis of industry.