High-performance liquid chromatographic monitoring of intravenously administered diacetylmorphine and morphine and their metabolites in human plasma

A rapid and selective reversed-phase high-performance liquid chromatographic assay with gradient elution and diode-array detection for diacetylmorphine, morphine, codeine, and their free and glucuronidated metabolites in plasma, was developed. After addition of ethylmorphine as internal standard the plasma samples were extracted using C-18 ODS-2 solid-phase columns with a recovery better than 80%. The limit of quantitation using an injection volume of 2 mu l was 25 ng/ml for each compound. The intra- and inter-day precision was better than 5%. The described method cannot only be used for pharmacokinetic studies but also for intoxication cases to monitor a wide range of opiates.