Packed in‐tube SPME–LC–MS/MS for fast and straightforward analysis of cannabinoids and metabolites in human urine

Abstract

Cannabinoids are pharmacologically active compounds present in cannabis plants, which have become important research topics in the modern toxicological and medical research fields. Not only is cannabis the most used drug globally, but also cannabinoids have a growing use to treat a series of diseases. Therefore, new, fast, and efficient analytical methods for analyzing these substances in different matrices are demanded. This study developed a new packed-in-tube solid-phase microextraction (IT-SPME) method coupled to liquid chromatography with tandem mass spectrometry (LC-MS/MS), for the automated microextraction of seven cannabinoids from human urine. Packed IT-SPME microcolumns were prepared in (508µm i.d.×50mm) stainless-steel hardware; each one required only 12mg of sorbent phase. Different sorbents were evaluated; fractional factorial design 24-1 and a central composite design were employed for microextraction optimization. Under optimized conditions, the developed method was a fast and straightforward approach. Only 250µl of urine sample was needed, and no hydrolysis was required. The sample pretreatment included only dilution and centrifugation steps (8min), whereas the complete IT-SPME-LC-MS/MS method took another 12 min, with a sample throughput of 3 samplesh-1 . The developed method presented adequate precision, accuracy and linearity; R2 values ranged from 0.990 to 0.997, in the range of 10-1000ngml-1 . The lower limits of quantification varied from 10 to 25ngml-1 . Finally, the method was successfully applied to analyze 20 actual urine samples, and the IT-SPME microcolumn was reused over 150 times.