FLOW-INJECTION ANALYSIS WITH AMPEROMETRIC DETECTION OF NALTREXONE IN PHARMACEUTICALS

Flow injection analysis (FIA) with amperometric detection using a carb on paste electrode is applied to the determination of naltrexone. The sample solution was injected into the carrier stream of 0.1 M perchlor ic acid, being determined by oxidation at +1.0V vs. Ag/AgCl/sat. KCl u sing a flow rate of 4 ml min(-1). A relative standard deviation of 1.5 % was calculated for a concentration level of 10(-5) M (n = 17) withou t carrying out a carbon paste electrode pretreatment. Calibration curv es were found to be linear between 2x10(-8) and 10(-5) M (almost three orders of magnitude) and the method has a detection limit of 2x10(-8) M. A simple and reproducible procedure is proposed for the determinat ion of naltrexone in pharmaceuticals. The results compared favourably with those obtained by an HPLC-UV method. (C) 1997 Elsevier Science B. V.