Determination of atmospheric sulfur dioxide by ion chromatography in the city of Cabimas, Venezuela

Sulfur dioxide (SO2) is an atmospheric pollutant that at certain concentrations may produce harm to human health and contribute to acid rain formation. Measurements of SO2 concentrations were made at two sampling sites in the city of Cabimas, Venezuela, during several months of the dry season (March and April) and of the rainy season (May to July) of 1994. SO2 samples were collected in a dilute solution of hydrogen peroxide (H2O2) with a Graseby/Andersen sampler, Model 209068 and analyzed as sulfate by ion chromatography (IC) using Dionex equipment, Model 2000i/sp. The detection limit for sulfate was 0.044 mu g/ml, based on three times the standard deviation of the blank (n=23). For a sulfate sample with a mean of 0.198 mu g/ml (n=7), a relative standard deviation of 5.56% was obtained. The recovery of a sulfate standard (0.2 mu g/ml) was 99%, The pararosaniline method was also used during the dry season in order to compare the results. Most of the SO2 concentrations were detected during the dry season by the H2O2 IC method. The average concentrations at the sampling sites were 15.4 mu g/m(3) (n=14) and 16.6 mu g/m(3) (n=15). The total average (16.0 mu g/m(3)) represents 20% of the lowest Venezuelan air quality standard (80 mu g/m(3)).