Determination of Part-per-Trillion Levels of Sulfur Dioxide in Humid Air

Abstract

Measurement of low part-per-trillion levels of sulfur dioxide by chromatographic techniques requires cryogenic preconcentration. To prevent loss of sulfur dioxide in the cotrapped water when sampling humid ambient air, we have used tubing made of Nation perfluorinated membrane to dry the sampled air at flow rates of 0.25-1.0 L/min. The lower limits of detection (LLD) on polyphenyl ether/Chromosorb T columns depend on column length, sample volume, and base line chromatogram noise. For a 3-L sample collected in 3 min the LLD is 13 parts per trillion by volume for a 6-m column with peak resolution to the base line from interfering compounds in ambient air. © 1986, American Chemical Society. All rights reserved.