SPECTROPHOTOMETRIC DETERMINATION OF HYDROGEN-PEROXIDE IN RAINWATER

Hydrogen peroxide in rainwater has been determined from the measuremen t of absorption at 432 nm after the formation of the stable oxo-peroxo -pyridine-2,6-dicarboxylatovanadate(V) complex (OPDV) in acid media. D eterminations were in good agreement with those using a modified p-hyd roxyphenylacetic acid (PHPA) emission method. The linear range for the OPDV method is from 0.05 to 50 ppm H2O2, and the limit of detection u nder the analytical conditions employed was 5.8 nmol H2O2 for a 20 cm( 3) rainwater sample. The volume weighted mean H2O2 concentration in ra inwater collected at roof-top level in central Kowloon was 15.9 mu M ( N=10), and the ratio of non-sea salt sulphate and H2O2 concentrations was significantly correlated with pH. The OPDV absorption method was a lso employed for the determination of ambient gaseous H2O2, and liquid -nitrogen cold-trap collection gave results about 30% lower than impin ger sampling, where artifact H2O2 formation occurred. (C) 1998 Elsevie r Science B.V. All rights reserved.