Method development for simultaneous determination of amphetamine type stimulants and cannabinoids in urine using GC-MS

In this study, the method for simultaneous determination of amphetamine-type stimulant drugs and cannabinoids using GC-MS was developed for urinalysis. For the improvement of analytical efficiency, tri-fluoroacetic anhydride and pentafluoropropanol were used as derivatization reagents and derivatization conditions such as compositions, reaction time, and temperature were optimized. Also metabolically generated glucuronides such as 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol were removed through alkaline hydrolysis. The extraction method was optimized by changing the pH of urine and extraction time. The limit of detection (LOD) was 0.49-1.71 ng/mL as 3 signal-to-noises (s/n) whereas the limit of quantification (LOQ) of 10 s/n was 1.62-5.70 ng/mL. Repeatability and reproducibility were obtained as inter-day (n = 5), intra-day (n = 3), and inter-person (n = 3). The measured accuracy ranged as inter-day: -9.0-9.1%, intra-day: -10.2-12.6%, and inter-person: -12.9-8.2%, and the precisions were estimated as inter-day: 0.5-16.1%, intra-day: 2.1-14.2%, and inter-person: 0.8-19.3%. This method was also successfully applied to real samples. (C) 2013 Elsevier B.V. All rights reserved.