HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ELECTROSPRAY MASS-SPECTROMETRIC DETERMINATION OF MORPHINE AND ITS 3-GLUCORONIDES AND 6-GLUCURONIDES- APPLICATION TO PHARMACOKINETIC STUDIES

A rapid and selective assay of morphine and its 3- and 6-glucuronides in serum, based on high-performance liquid chromatography-electrospray mass spectrometry has been developed. The analytes and the internal s tandard, codeine or naltrexone, were subjected to solid-phase extracti on, using ethyl solid-phase extraction columns, prior to chromatograph y. A reversed-phase column and a gradient mobile phase consisting of w ater and methanol were used. The mass spectrometer was operated in the selected-ion monitoring mode. The following ions were used: m/z 286 f or morphine, m/z 300 for codeine, m/z 342 for naltrexone, and m/z 462 for morphine 3- and 6-glucuronides. The limit of quantitation observed with this method was 10 ng/ml morphine, 50 ng/ml morphine-6-glucuroni de and 100 ng/ml morphine-3-glucuronide. The present method proved use ful for the determination of serum levels of the parent drug and its m etabolites in pain patients, heroin addicts and in morphine-treated mi ce.