Determination of atmospheric sulphur dioxide by solid-phase spectrophotometry

Abstract

A solid-phase spectrophotometric method for the determination of sulphite and its application to the determination of atmospheric sulphur dioxide is described. In this method, sulphur dioxide is trapped with morpholine to form an adduct which reacts with pararosaniline and formaldehyde, and the reaction product is sorbed on Dowex 1-X8 resin. The absorbance of the resin phase at 565 and 700 nm is measured directly, allowing for the determination of sulphur dioxide in the range 4–56 µg l^–1 in solution, with a relative standard deviation of 2.1%. The method was applied to the determination of sulphur dioxide in air samples from laboratory emissions.