Determination of opiates and cocaine in hair as trimethylsilyl derivatives using gas chromatography-tandem mass spectrometry

An analytical method for the determination of heroin, 6- monoacetylmorphine, morphine, codeine, cocaine, benzoylecgonine, and cocaethylene in human hair using gas chromatography-tandem mass spectrometry is presented. The analytes were extracted from finely cut hair with methanol at 56°C for 18 h in the presence of nalorphine as the internal standard. After the incubation, methanol was evaporated to dryness, and all the analytes, except heroin, cocaine, and cocaethylene, were converted to their trimethylsilyl derivatives. The reaction products were identified and quantitated using product ions formed from the parent ions by collision- induced dissociation in the ion-trap mass spectrometer. This method provided excellent sensitivity and specificity for analytes at the concentrations usually found in the keratin matrix.