Analytical method development and validation of a serum LC–MS/MS assay for 2 emerging synthetic cannabinoids

BACKGROUND: This study aimed to develop and validate a highly sensitive and reproducible liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of 5F-MDMB-PICA and MDMB-4en-PINACA in human serum, ensuring suitability for both forensic and clinical toxicology applications. METHODS: Drug-free serum samples were fortified with target analytes, extracted through solid-phase extraction, and analyzed using a triple-quadrupole LC-MS/MS system (Shimadzu LCMS-8045) equipped with a biphenyl column. Calibration was established within 1-100 ng/mL, and validation parameters - linearity, sensitivity, accuracy, and precision - were assessed according to international guidelines. RESULTS: The calibration curves displayed excellent linearity (r2 = 0.999) for both analytes. The limits of detection were 0.113 ng/mL for 5F-MDMB-PICA and 0.145 ng/mL for MDMB-4en-PINACA, with limits of quantification of 0.339 ng/mL and 0.435 ng/mL, respectively. Recovery rates at 10 and 50 ng/mL ranged from 77.7% to 96.4%, while intra and inter-day precision (relative standard deviation %) remained below 15%. CONCLUSION: The validated method provides reliable quantification of 5F-MDMB-PICA and MDMB-4en-PINACA in human serum. The observed linearity, sensitivity, recovery, and precision support its applicability for routine forensic toxicology analyses.