Analysis of Sulfur-Containing Gases in the Ambient Air Using Selective Pre-Filters and a Micro-coulometric Detector

Abstract

A sulfur-sensitive, coulometric, microtitration cell, originally designed as a gas chromatographic detector, has been converted to direct atmospheric analysis by continuously pumping ambient air through the cell. A method is suggested for sequentially separating H₂S, S0₂, CH₃SH, CH₃SCH₃, and CH₃SSCH₃ in ambient air by using a series of chemically-impregnated membrane filters. Chemical imprégnants have been developed which retain one or more of these compounds from mixtures and allow the others to pass quantitatively. Those sulfur compounds remaining in the air stream emerging from each selective filter are then analyzed with the microtitration cell. Air is sequentially sampled through an appropriate series of filters to provide a continuous, step-wise analysis of typical sulfur-containing gases. Over 100 potentially selective formulations were studied. The basis for collection of each type of sulfur-containing gas is discussed.