Determination of gas-phase dimethyl sulfate and monomethyl sulfate.

Analytical techniques were developed for the collection and determination of gas-phase dimethyl sulfate and monomethyl sulfuric acid in the flue lines and plumes of power plants and in the ambient atmosphere. The techniques involve the collection of the gas phase species in denuders which are selective for monomethyl sulfuric acid or which collect both dimethyl sulfate and monomethyl sulfuric acid, and determination of the deposition pattern of the collected alkyl sulfates in the denuder. In addition, both dimethyl sulfate and monomethyl sulfuric acid are collected in filter pack, sorbent-bed combinations which allow for the separate determination of both dimethyl sulfate and monomethyl sulfuric acid or for their joint collection and determination. Monomethyl sulfuric acid is determined by ion chromatography. Dimethyl sulfate is determined either by ion chromatography or by gas chromatography, depending on the collection device used.