TRACE DETERMINATION OF HYDROXYL RADICAL IN BIOLOGICAL-SYSTEMS

A simple and highly sensitive method to quantify the rates of producti on of OH in biological systems is described. This method employs the r eaction between OH and dimethyl sulfoxide to generate quantitatively a methyl radical, which then reacts with a fluorescamine-derivatized ni troxide to produce the stable O-methylhydroxylamine. This O-methylhydr oxylamine is separated by reversed-phase high-performance liquid chrom atography and quantified fluorometrically, The estimated detection lim it of the O-methylhydroxylamine is 3.5 nM for a 50 mu L injection at a signal to noise ratio of 2. The method is applied to the determinatio n of the rates of OH production in a biologically relevant model syste m and in a mouse epidermal cell line treated with a quinone anticancer compound.