The methylthymol blue (MTB), modified Brosset, and barium chloranilate sulfate methods were evaluated for precision, accuracy, working range, interference effects, and degree of agreement with x-ray fluorescence analysis (XRF) using atmospheric particulate samples. The samples used were collected simultaneously with glass fiber, quartz fiber and Fluoropore filters, the latter being used in a dichotomous sampler. Studies of interference effects were based upon measured concentrations of potential interferents extractable from the particulate matter as well as the filter media. The results demonstrated agreement within 16% for determining atmospheric sulfate concentrations by the three wet chemical procedures with all the filter media. XRF results on the 'fine' Fluoropore samples agreed within 10% of those obtained by wet chemical procedures on the samples and were, on average and within experimental error, equivalent to results obtained by the MTB method on 8 x 10 inch glass fiber high volume samples. Small differences in results obtained with different filter media in the present study are more consistent with the effects of analytical interferents rather than artifact sulfate formation as the cause.

"EPA-600/7-77-128." "November 1977." "Interagency Energy-Environment Research and Development Program report." Includes bibliographical references. Final report.