KINETIC DETERMINATION OF MORPHINE IN ILLICIT POWDERS, USING A FLUORIDE SELECTIVE ELECTRODE, BASED ON REACTION WITH 1-FLUORO-2,4-DINITROBENZENE

A simple, accurate and selective method is described for the determina tion of morphine in illicit powders, based on monitoring the initial r ate of fluoride ion liberation from the reaction of morphine with 1-fl uoro-2,4-dinitrobenzene at pH 9 and 35 degrees C, using a solid-state fluoride ion-selective electrode. Under optimized reaction conditions, as little as 15 mu g/ml of morphine is determined with an average rec overy of 99.5% and a mean relative standard deviation of 1.2%. Determi nation of morphine in real illicit powders containing 6-18% morphine g ives results comparing favorably with those obtained from isocratic re verse-phase high-performance liquid chromatography. No interferences a re caused by many structurally related and associated compounds such a s codeine, acetylcodeine, ethylmorphine, acetylmorphine and diacetylmo rphine (heroin).