Spectrophotometric determination of hydrogen peroxide in rainwater

Hydrogen peroxide in rainwater has been determined from the measurement of absorption at 432 nm after the formation of the stable oxo-peroxo-pyridine-2,6-dicarboxylatovanadate(V) complex (OPDV) in acid media. Determinations were in good agreement with those using a modified p-hydroxyphenylacetic acid (PHPA) emission method. The linear range for the OPDV method is from 0.05 to 50 ppm H2O2, and the limit of detection under the analytical conditions employed was 5.8 nmol H2O2 for a 20 cm(3) rainwater sample. The volume weighted mean H2O2 concentration in rainwater 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 also employed for the determination of ambient gaseous H2O2, and liquid-nitrogen cold-trap collection gave results about 30% lower than impinger sampling, where artifact H2O2 formation occurred. (C) 1998 Elsevier Science B.V. All rights reserved.