Detection and quantification of 5F-ADB and its methyl ester hydrolysis metabolite in fatal intoxication cases by liquid chromatography-high resolution mass spectrometry

5F-ADB (methyl 2-([1-(5-fluoropentyl)-1H-indazole-3-carbonyl]amino}-3,3-dimethylbutanoate) is a frequently abused new synthetic cannabinoid that has been sold since at least the end of 2014 on the drug market. It has been classified as an illicit drug in most European countries, and also in Turkey, Japan, and the United States. In this study, 5F-ADB and its methyl ester metabolite were determined in the blood and urine samples taken from fatal cases using liquid chromatography-highresolution mass spectrometry (LC-HRMS). The extraction of samples was performed using a solid-phase extraction method, followed by LC-HRMS analysis. The method was fully validated for linearities, limits of detection (LODs), limits of quantification (LOQs), recoveries, matrix effects, process efficiencies, accuracies, precisions, and stabilities and was applied to 70 blood and 36 urine samples from fatal cases where 5F-ADB was the only drug detected. The LODs were between 0.08 and 0.10 ng/mL, and LOQs were between 0.10 and 0.12 ng/mL for both blood and urine samples. 5F-ADB and its methyl ester hydrolysis metabolite were found at the blood concentrations ranging from 0.10 to 1.55 ng/mL (mean = 0.40 ng/mL) and 0.15 to 23.4 ng/mL (mean = 2.69 ng/mL), respectively. 5F-ADB was not detected in any urine samples. 5F-ADBmethyl ester hydrolysis metabolite was detected in 35 urine samples with a detection range of 0.28-72.2 ng/mL and a mean of 9.02 ng/mL. The synthetic cannabinoid 5F-ADB and its methyl ester metabolite were identified and quantified in authentic human blood and/or urine specimens obtained from 70 fatal cases. The method was successfully applied to postmortem blood and urine samples. (C) 2019 Elsevier B.V. All rights reserved.