Hair samples cocaine and morphine quantification by chromatography mass spectrometry

Purpose: The analyses of xenobiotics (XB) are usually performed on blood or urine and, in post-mortem cases, on liver or kidney tissues. Nevertheless, blood and urine specimens only reflect recent exposure. Therefore, it is imperative the use of an alternative biological matrix that may provide relevant and important retrospective information about the use of drugs, namely cocaine and morphine which are commonly abused. Methods: A qualitative and quantitative method for the simultaneous determination of cocaine and morphine in human hair was developed and validated. After decontamination, hair samples (20 mg) were incubated with a mixture of methanol/hydrochloric acid (2:1) at 65 °C overnight in order to extract the XBs of the matrix. Samples were cleaned-up by mixed-mode solid-phase extraction (SPE), XBs were derivatized with N-methyl-N-(trimethylsilyl) trifluoroacetamide and then analyzed by gas chromatography/electron impact/mass spectrometry (GC/EI/MS). Results of the study: The developed method proved to be specific, accurate and precise across the calibration range (0.25–10 ng/mg), where good linearity was observed for both the analytes with correlation coefficients ranging 0.999 and 0.9993. The coefficients of variation oscillated between 0.18% and 16.16%. The limits of quantification (LOQ) were 0.04 and 0.05 ng/mg for cocaine and morphine, respectively. The proposed GC/EI/MS method can be successfully applied in the screening and quantification of these XBs in real cases, namely in clinical and forensic toxicology.