1) Hunt, D. F.; Shabanowltz. J.; Harvey, T. M.; Coates, M. Anal. Chem. 1985, 5 7 , 525-537. McMuttrey, K. D.; Wildman, N. J.; Tai, H. Bull. Environ. Toxicol. 1983, 31 ~ 734-737. van Graas, 0.; de Leeuw, J. W.; Schenck, P. A. in Advances h Organic Geochemistry 1979; Douglas, A. G., Maxwell, J. R., Eds.; Pergamon: London. 1980 DD 485-494. van de W n t I D.; Brown, S. c.; philp, R. P.; Simonett, B. R. T. GWchlm. C o s m h l m . Acta W80, 4 4 , 999-1013. van de Meent, D.; de Leeuw, J. W.; Schenck, P. A. J. Anal. Appl. fvrol. 1980. 2 . 249-263. Schenck, P.' A.; de Leeuw, J. W.; Viets, T. C.; Haverkamp, J. I n Petroleom, Geochemkf?y and Exploration of Europe; Brooks, J., Ed.; Blackweil Scientlfic: 1983; pp 267-274. van der Kaaden. A.; Boon, J. J.; de Leeuw, J. W.; de Lange, F.; Schuyi, P. J. W.; Schulten, H. R.; Bahr, U. Anal. Chem. 1884, 56, SaizJimenez, C.; de Leeuw, J. W. Org. Geochem. 1984, 6 , SaizJimenez, C.; de Leeuw, J. W. Org. Geochem. 1984, 6 , Nlp. M.; de Leeuw. J. W.; Schenck, P. A.; Meuzeiaar, H. L. C.; Stout, S. A.; Given, P. H.; Boon, J. A method for the determlnatlon of hydrogen peroxide In the amblent atmosphere is described, using bnplnger or dlffuslon scrubber collectlon of H,02 wlth aqueous-phase analysis by an enzyme-catalyzed fluorescence technique. Interference from ozone at amblent levels Is removed by gas-phase reactlon wtth excess nltrlc oxlde. The lmplnger and dMuslon scrubber collectlon technlques glve equlvalenl results for atmospherlc gas-phase H202 wtth h l t s of detectkn of 0.1 ppbv for approximately 60-mln and 10-mln sampllng times, respectlvely . The development of techniques for measuring gaseous and aqueous HzOz and other hydroperoxy compounds has been the focus of substantial research effort following the recog-Permanent address: Practical Engineering College of Beer-Sheva, P.O. Box 45, Beer-Sheva, Israel.nition that HzOz could rapidly oxidize dissolved S(1V) compounds to sulfuric acid throughout the normal pH range of rain, cloud, and fog waters (pH 2-7) (1,2). The high solubility of HzOz in water (Henry's law constant -lo5 M atm-') leads to significant aqueous concentration (1-100 MM) in, e.g., cloud water, even a t low parts-per-billion by volume gaseous HzOz concentrations in air entering clouds (3-5). Several methods for determining aqueous-phase HzOz in atmospheric samples have been developed or improved recently based on luminol chemiluminescence (61, (p-hydroxypheny1)acetic acid (POH-PAA) dimer fluorescence (5, 7-9), scopoletin fluorescence quenching (lo), and peroxyoxalate chemiluminescence (I 1).Measurements of gas-phase hydrogen peroxide have been attempted by collection of the peroxide in aqueous solution using impingers or condensation collection devices (12).However, these efforts have been shown to give unreliable resulta due to the in situ formation of hydrogen peroxide from low-solubility constituents of ambient air and/or compressed air during collection (13-15). It has been suggested that this