Abstract
Some plastic syringes introduce a nitroxide free radical into the fluids they contain. The EPR spectrum shows a triplet with aN = 17.0 +/- 0.1 G in plasma. We report here that this nitroxide/hydroxylamine couple serves as an antioxidant system, whose redox potential appears to be between that of vitamin C and vitamin E. This adventitious antioxidant can alter the course of free radical processes.