Toxicology of Sulphur Dioxide and its Spectrophotometric Determination in Air Using a New Absorbing Agent

An aqueous solution of malonyldihydroxamic acid is proposed for the absorption of atmospheric sulphur dioxide. The reagent has an absorption efficiency of ∼100% and the resulting sulfite solution is stable for more than 30 days. The effect of variables for absorption of sulphur dioxide such as reagent concentration, flow rate and temperature has been investigated. The absorbed sulphur dioxide has been subsequently determined spectrophotometrically by p-aminoazobenzene-formaldehyde reagent in hydrochloric acid medium at optimized conditions. The pink coloured dye has a γmax at 505 nm. The interference of nitrogen dioxide has been removed by use of sodium azide/oxalyldihydrazide. The proposed reagent is superior to TCM method in regard of manipulation, speedy results, use of stable and freely available pure and non-toxic reagents. The procedure has been applied for analysis of sulphur dioxide in vicinity of steel plant and work room air. Key Words: Sulphur dioxideairadsorption solutionmalonyldihydroxamic acid.