Determination of 465 psychoactive substances, drugs and their metabolites in urine by LC-MS/MS

Abstract

Due to the emergence of novel psychoactive substances on the drug market, there is a growing demand for analytical methods allowing identification and determination of as many psychoactive substances as possible in the shortest possible time, which can be easily expanded to include additional analytes appearing in street trade. Immunochemical methods are not sufficient to meet constantly growing requirements. Therefore, the aim of the study was to develop an analytical method enabling quick analysis of urine samples for psychoactive substances, drugs and their metabolites. Liquid–liquid extraction (LLE) and liquid chromatography coupled with mass spectrometry (LC-MS/MS) were used for this purpose. Using available analytical standards, the operating parameters of the mass spectrometer were selected for each of the 477 analytes, and MRM (multiple reaction monitoring) acquisition was selected for each of them. The use of analytical standards allowed for the identification of analytes separated on the chromatography column. The exceptions are methylmethcathinone isomers (3-MMC and 4-MMC), which we were unable to separate using the gradient elution method used. Extraction using acetonitrile with the addition of ammonium formate and formic acid allowed us to obtain high recoveries without the use of β-glucuronidase. Recovery values ranged from 18.43 to 119.94%. The matrix effect was eliminated by obtaining a calibration curve in the matrix. The developed analytical method was validated in accordance with SWGTOX guidelines. Only 12 substances did not meet the validation criteria (CV: ±20% and bias: ±20%). Thus the validated method makes it possible to determine 465 psychoactive substances in just 30 minutes. In the validation process, values such as the limit of detection (LOD) and the limit of quantification (LOQ) were also determined. The LODs are in the range of 3–30 ng mL⁻¹, and the LOQs are in the range of 10–100 ng mL⁻¹. The method was successfully applied to toxicological analyses of urine samples, which was an opportunity to develop it further to meet the needs of toxicology.