Hydrogen peroxide method intercomparision study in seawater

Hydrogen peroxide (H2O2) has been studied extensively in the atmosphere and natural waters employing numerous techniques based on absorbance, voltammetry, fluorescence or chemiluminescence. Here we compare the 10-methyl-9-(p-fonnylphenyl)-acridinium carboxylate trifluoromethanesulfonate chemiluminescent-based (AE-CL) flow-injection analysis (FIA) method to the p-hydroxyphenylacetic acid (POHPAA) batch fluorescence method on 108 paired samples representing a wide range of ocean water types. Over the oceanographically relevant concentration range of 0-250 nM, the two methods are indistinguishable. Since the AE-CL method does not respond to t-butyl hydroperoxide, and no other species including trace metals have been found to cause interferences, it an ideal method for quantification of H2O2 in natural waters. The POHPAA method, which cannot distinguish organic peroxides from H2O2, was also compared to the HPLC method of Lee et al. The latter method separates organic peroxides from H2O2 and then measures the concentration of each species. These two methods produced results that are not significantly different from each other, demonstrating that hydrogen peroxide is the only peroxide detected in seawater. It can be inferred from these studies that previous H2O2 measurements made with nonselective techniques measure H2O2 in seawater, and that organic peroxides comprise an insignificant fraction of the total peroxide signal. This study also validates the use of the HPLC method for seawater analyses, as the method was originally developed for atmospheric gas-phase studies. (c) 2005 Elsevier B.V. All rights reserved.