Liquid chromatography-tandem mass spectrometry method for the simultaneous analysis of multiple hallucinogens, chlorpheniramine, ketamine, ritalinic acid, and metabolites, in urine

Abstract

A validated method for the simultaneous analysis of multiple hallucinogens, chlorpheniramine, ketamine, ritalinic acid, and several metabolites is presented. The procedure comprises a sample clean-up step, using mixed-mode solid-phase extraction followed by liquid chromatography (LC)-tandem mass spectrometry analysis. Chromatographic separation was achieved using a Sunfire C(8) column eluted with a mixture of formate buffer, methanol, and acetonitrile. The applied LC gradient ensured the elution of all the drugs examined within 14 min and produced chromatographic peaks of acceptable symmetry. Selectivity of the method was achieved by a combination of retention time and two precursor-product ion transitions for the non-deuterated analogues. Validation of the method was performed using 500 microL of urine. The limits of quantification (LOQ) for LSD and 2-oxo-3-hydroxy-LSD were 0.05 and 1 ng/mL, respectively, and ranged, for the other hallucinogens, from 0.5 to 10 ng/mL. Linear and quadratic regression was observed from the LOQ of each compound to 12.5 ng/mL for LSD, 50 ng/mL for 2-oxo-3-hydroxy-LSD and 500 ng/mL for the others (r(2) > 0.99). Precision for the QC samples, spiked at a minimum of two concentrations, was calculated [%CV and %bias < 20% for most of the compounds, except for bufotenine and cathinone (%bias < 24%), and ibogaine (%bias < 30%)]. Extraction was found to be both reproducible and efficient with recoveries > 87% for all the analytes. Furthermore, the processed samples were demonstrated to be stable in the autosampler for at least 24 h. Finally, the validated method was applied to the determination of chlorpheniramine, ketamine, LSD, and psilocin in authentic urine samples.