A chemiluminescence method for the analysis of H2O2 in natural waters

Hydrogen peroxide (H2O2) was determined at nanomolar levels in natural waters by a chemiluminescent method involving reaction of hydrogen peroxide with an acridinium ester 10-methyl-9-( p-formylphenyl)-acridinium carboxylate trifluoromethanesulfonate. The method is simple, rapid, requires no catalyst or metal ion complexes, and has an analytical precision of 4% RSD at typical natural water concentrations. The analysis also produces a linear response over the concentration range, 5 x 10(-9) to 60 x 10(-6) M, simply by changing the pH of the solution prior to addition of the acridinium compound or by varying the concentration of the acridinium ester at constant pH. The detection limit is 5 nM and is limited primarily by the capability to obtain H2O2-free blank water. Analytical results were verified in distilled and a variety of natural water matrices by intercomparison with a completely independent fluorescence decay technique involving the hydrogen peroxide oxidation of the fluorophore scopoletin. The two methods produced results with no statistical differences in the data at the 99.9% confidence level. In addition, the method does not suffer from background fluorescence matrix effects in organic-rich environments, which hinders the applicability of commonly used natural water hydrogen peroxide analyses. Application of the method to these highly fluorescent waters is also presented. (C) 2000 Elsevier Science B.V. All rights reserved.