DETERMINATION OF PASSIVE-SAMPLED SULFUR-DIOXIDE IN AMBIENT AIR AS SULFATE ION BY FLOW-INJECTION ANALYSIS WITH AN IN-LINE REACTION COLUMN

A modified FIA method was developed for the determination of sulphur d ioxide (SO2) in ambient air collected by a passive sampler. SO2 was ox idized by hydrogen peroxide and determined as sulphate ion in solution . Barium-dimethylsulfoazo-III complex was used as spectrophotometric r eagent. A BaSO4-immobilized in-line reaction column was introduced int o the flow system to increase the sensitivity and reproducibility. An in-line cation exchange column was used to eliminate triethanolamine, which was used as the absorbent reagent in the passive sampler. Sulpha te ions can be analyzed in the range of 0.08-10.00 mg l(-1) with the R .S.D. less than 1.6% at the rate of 15 samples h(-1). It was satisfact ory to apply this method to the analysis of sulphur dioxide in ambient air and the results agreed with those obtained by ion chromatography. (C) 1997 Elsevier Science B.V.