Determination of subnanomolar levels of hydrogen peroxide in seawater by reagent-injection chemiluminescence detection

A reagent-injection chemiluminescent method for the determination of hydrog en peroxide (H2O2) has been developed. The method is based on the catalytic (cobalt (IT)) oxidation of luminol by hydrogen peroxide in an alkaline sol ution. One mixed reagent is used for the analysis using the reagent injecti on method. The mixed reagent is optimized for pH and concentration of lumin ol and Co2+. Apart from Fe2+, none of the 14 species tested showed interfer ence at their seawater levels. Because Fe2+ oxidation is rapid compared to the rate of decay of hydrogen peroxide, the Fe2+ interference can be elimin ated by storing seawater samples for 1 h. The combination of reagents and t he adaptation of reagent injection lead to a subnanomolar detection limit. The accuracy of the method is at least 0.42 nM. The precision of the method is 17 pM (for a 0.57 nM sample). The method has been used aboard ship to d etermine the concentrations of hydrogen peroxide in seawater samples in the open ocean as well as on the continental shelf.