A new sensitive assay for the measurement of hydroperoxides

The enzyme glutathione (GSH) peroxidase can be used to measure hydroperoxides quantitatively, easily, and specifically. A timed reaction of GSH peroxidase, coupled with the oxidation of NADPH by GSH reductase, allows a direct spectrophotometric measurement of hydroperoxide. Addition of catalase prior to the addition of GSH peroxidase permits the distinction between hydrogen peroxide and organic hydroperoxides. The solvents that can be used with the assay include methanol, ethanol, water, and aqueous solutions of detergents such as Brij 35, Triton X-100, and cetyl trimethyl ammonium bromide. The utility of the method is demonstrated by the measurement of hydrogen peroxide and organic hydroperoxides formed upon ozonolysis of an unsaturated fatty acid.