Simultaneous solid-phase extraction on C18 cartridges of opiates and cocainics for an improved quantitation in human hair by GC-MS: one year of forensic applications.

We have developed a new solid-phase extraction (SPE) on C18 cartridges which allows a very simple protocol of manipulation and a single elution of opiates and cocainics from human hair samples. The method involved decontamination in a phosphate buffer and dichloromethane, pulverization in a ball mill, addition of deuterated internal standards, heated acid hydrolysis and SPE. Quantitation utilized gas chromatography and mass spectrometry. Between days precise study gave relative standard deviations always inferior to 8.9% for each compound at 4 ng/mg (except methylecgonine ester = 15.7%). Accuracy was tested using a t-statistic versus a reference material from the NIST. Limits of detection were calculated from an analysis of the blanks which contained between 0.12 and 0.28 ng/mg for each drug. The method was applied in forensic cases for 1 year of toxicological activity. Among the 108 analyses performed, 30 were positive for cocaine and 33 for opiates. Concentrations were in the range 0.9-242.0 ng/mg (cocaine), 0.3-71.3 ng/mg (benzoylecgonine), 0.0-9.8 ng/mg (methylecgonine ester), 0.0-2.9 ng/mg (cocaethylene), 0.1-11.5 ng/mg (codeine), 0.4-44.6 ng/mg (morphine) and 0.7-131.2 ng/mg (6-acetylmorphine). Ratios of the metabolites to parent drugs were proposed to avoid risk of external contamination.