Sampling and Analysis of Sulfur Dioxide and Particulate Sulfate in Air Using Impregnated Filters

Abstract

A simple procedure for simultaneous sampling, but separate analysis of SO₂ and SO^2- ₄ is described in this paper. Both species are collected on one and the same impregnated filter. Using tetrachloromercurate solution for impregnation, sulfur dioxide is effectively absorbed and stabilized as sulfite, but can easily be separated from the co-collected sulfate by a microdiffusion step. By this means both species can be determined in one sample by isotope dilution analysis (IDA). Because the humidity of the impregnated filter has a distinct influence on the collection efficiency for SO₂, it is recommended to use the proposed technique for short-term sampling.