Method Development for the Detection of Basic/Weak Basic Drugs in Hair by LCMSMS: Comparison between Methanolic and Alkaline Extraction on Real Samples

Detection of drugs in hair has become popular in recent years. The significantly long drug detection window (months) in hair has allowed the retrospective investigation and measurement of past consumption of drug. As the majority of drugs are basic, an extraction method was developed based on a methanolic solution for detection of basic/weak basic drugs in hair. It was compared with alkaline digestion (NaOH) followed by LLE. A filtration step with filtration vials was added and their materials were compared. After filtration, extracts were injected directly onto a C18 column coupled to Sciex ABI 2000 MSMS. The mobile phase was 50% methanol, 0.1% formic acid and 2 mM ammonium acetate (isocratic). Both methods were compared by applying them to real samples. Results showed that calibration was linear with r2 of 0.991-0.999 for 20 tested analytes. The matrix effect was assessed to be between 91.4%- 110.2% for 18 analytes. PTFE filter material showed better recoveries over the GMF and PVDF based filters. Stability of analytes during extraction in general was better with methanolic incubation rather than alkaline digestion. With regard to real sample recovery, 6 out of 10 analytes recovered better with alkaline digestion. In conclusion, the methanolic method is capable of extracting most basic drugs in hair samples but only part of the total incorporated drug. Therefore, these results suggest that a combination of both methods (methanolic and alkaline extractions) in hair sample processing for general detection of basic and weak basic drugs may produce better results. However, not all basic drugs are stable under alkaline digestion.