Quantification of seven novel synthetic opioids in blood using LC–MS/MS

Abstract

Purpose: The objective of this study was to develop, optimize, and validate a method for the simultaneous quantification of U-47700, AH-7921, U-49900, U-50488, MT-45, W-18, and W-15 in whole blood using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Methods: Blood samples (500 µL) were fortified with mixed calibrator or quality control (25 µL) and internal standard (10 µL) solutions. Analytes were isolated via a solid-phase extraction procedure. Analysis was performed using an Agilent 1290 Infinity II liquid chromatograph coupled to an Agilent 6470 triple quadrupole mass spectrometer. The method was validated in accordance with Scientific Working Group for Forensic Toxicology (SWGTOX) standard practices for method validation in forensic toxicology and applied to the analysis of postmortem blood specimens. Results: Lower limits of quantification were 0.25–1 ng/mL and the upper limits of quantification were 100 ng/mL. The coefficients of determination (R 2 ) for the calibration curves were > 0.99. Analytical bias, within-run imprecision, and between-run imprecision were within ± 15%, ≤ 16%, and ≤ 17%, respectively. All analytes were found to be stable at room temperature for 24 h, refrigerated (4 °C) for 72 h, and in the autosampler (4 °C) for 72 h. Authentic blood samples (n = 30) were analyzed using the validated method. Mean (range) U-47700 concentrations were 214 (3.2–1448) ng/mL in 15 cases. Conclusions: A quantification method for seven synthetic opioids (U-47700, AH-7921, U-49900, U-50488, MT-45, W-18, and W-15) in whole blood was developed, optimized, and validated in accordance with SWGTOX standard practices for method validation in forensic toxicology. This sensitive method was successfully applied to postmortem casework.