Determination of Various Drugs of Abuse in Oral Fluid by a Fabric Phase Sorptive Extraction–LC-MS/MS Method

Toxicological testing for drugs of abuse (DOAs) is an essential tool for healthcare practitioners and law enforcement agencies. Oral fluid (OF) is an alternative biological fluid for detecting recent DOA intake and is widely employed in forensic investigations. In the current study, a relatively novel and “green” fabric phase sorptive extraction (FPSE) procedure for sample preparation was coupled to liquid chromatography–tandem mass spectrometry (LC–MS/MS) to provide simplicity, cost-effectiveness, rapidity, low solvent consumption, and high analytical performance for the quantitative determination of ten commonly encountered DOAs and metabolites: amphetamine, benzoylecgonine, cocaine, codeine, ecgonine methyl ester, methadone, methamphetamine, 3,4-methylenedioxyamphetamine, 6-monoacetylmorphine, and morphine. The FPSE procedure was optimized by testing different filters, pH, extraction time, and solvents. The validated method demonstrated excellent linearity for all analytes, selectivity, acceptable precision, and high sensitivity (ranges for limits of detection (LODs) and quantification (LOQs) were 0.01–2 ng/mL and 0.03–6 ng/mL, respectively). Autosampler and short-term freeze stability exceeded 95% and 90% for all analytes, respectively. Overall, the combination of FPSE with LC–MS/MS provided a sensitive, selective, and environmentally friendly innovative analytical approach for the determination of DOA in OF and is suitable for both screening and confirmatory forensic and clinical applications.