A specific spectrophotometric determination of long chain nitro compounds and its application to NO2‐initiated lipid autoxidation

A specific spectrophotometric method is described for the determination of nitro‐β‐hydroperoxides produced during the initiation of lipid autoxidation by ppm NO2; this determination provides a measure of the rate of initiation by addition of NO2 to lipids. The nitro group is reduced to an amine using polymethylhydrosilane (PMHS) and Pd on charcoal, and the amine is then determined spectrophotometrically as a neutral methyl orange salt. Although this method was developed for the determination of micromolar quantities of nitro‐β‐hydroperoxides in lipid samples, it can be used to determine any long chain, nonpolar nitro compound. The method also can be adapted to allow the determination of polar or short chain nitro compounds by using a different amine determination.