Determination of new psychoactive substances and other drugs in postmortem blood and urine by UHPLC–MS/MS: method validation and analysis of forensic samples

This study aimed to validate a modified QuEChERS method followed by ultra-high performance liquid chromatography–tandem mass spectrometry to determine 79 new psychoactive substances (NPS) and other drugs in blood and urine. Prescription drugs (n = 23), synthetic cathinones (n = 13), phenethylamines (n = 11); synthetic cannabinoids (n = 8), amphetamines (n = 7) and other psychoactive substances (n = 17) were included in the method. 500 µL of biological fluid was extracted with 2 mL of water/ACN (1:1), 500 mg of anhydrous MgSO4/NaOAc (4:1) added, followed by a supernatant cleanup with 25 mg of primary secondary amine and 75 mg of anhydrous MgSO4. Quantification was done using matrix-matched calibration curves and deuterated internal standards. The method was satisfactorily validated for blood and urine at limit of quantifications ranging from 0.4 to 16 ng/mL, and applied to the analysis of 54 blood (38 postmortem and 16 antemortem) and 16 antemortem urine samples from 68 forensic cases. All urine samples and 59.3% of the blood samples were positive for at least one analyte. Twenty-two analytes were detected in at least one biological sample, including the synthetic cathinones ethylone (222 ng/mL, antemortem blood), eutylone (246 and 446 ng/mL, urine), and N-ethylpentylone (597 and 7.3 ng/mL, postmortem and antemortem blood, respectively). The validated method was shown to be suitable for the analysis of blood and urine forensic samples and an important tool to collect information on emerging drug threats and understanding the impact of NPS and other drugs in poisoning cases.