Simultaneous quantification of 37 synthetic cannabinoid metabolites in human urine by liquid chromatography-tandem mass spectrometry

Despite efforts by legal authorities to control the abuse of synthetic cannabinoids, new derivatives have continually emerged on the market to circumvent regulations, and its abuse has become a threat to public health. Thus, development of analytical methods for confirming drug intake in biological fluids is essential to ensure effective drug control and to address further drug intoxication cases. Herein, a sensitive and reliable liquid chromatography–tandem mass spectrometry method was established and validated for the simultaneous determination of 37 synthetic cannabinoid metabolites, such as N-hydroxypentyl and carboxy metabolites, using 100 μl of urine. Urine specimens were treated by enzymatic hydrolysis and solid-phase extraction. Limits of detection for the evaluated drugs ranged from 0.1 to 1 ng/ml, and the linear range spanned from 0.25 or 1 to 100 ng/ml. Precision and accuracy bias were 1.4–12.1 % and −7.2–7.2 %, respectively. Matrix effects biases were in the range of 0.4 to 10.1 %, and extraction recoveries were 65–99 %. In addition, all analytes were stable under storage conditions of 4 °C and −20 °C for 14 days, and after three freeze–thaw cycles. The developed method was successfully applied to actual urine specimens obtained from synthetic cannabinoid users. The present method enabled simultaneous quantification of 37 synthetic cannabinoid metabolites, including their regioisomers, in urine in the field of clinical and forensic toxicology.