Abstract
The advent of hundreds of new compounds aimed at the substance misuse market has posed new analytical challenges. A semi-quantitative liquid chromatography–high resolution mass spectrometry (LC–HRMS) method has been developed to detect exposure to two novel stimulants, mephedrone and ethylphenidate, and selected metabolites. Centrifuged urine (50 µL) was diluted with LC eluent containing internal standards (mephedrone-d3, methylphenidate-d9, and ritalinic acid-d10, all 0.02 mg/L) (450 µL). Intra- and inter-assay accuracy and precision were within ± 15% and < 6% respectively, for all analytes. The limit of detection was 0.01 mg/L all analytes. Urine samples from mephedrone and ethylphenidate users were analyzed using immunoassay (amphetamine-group CEDIA) and LC–HRMS. Ethylphenidate, mephedrone, and selected metabolites all had low cross-reactivity (<1%) with the immunoassay. The median (range) amphetamine-group CEDIA concentration in urine samples from mephedrone users (N = 11) was 0.30 (<0.041–3.04) mg/L, with only one sample giving a positive CEDIA result. The amphetamine-group CEDIA concentration in the urine sample from an ethylphenidate user was <0.041 mg/L. Improving the detection of novel compounds is of increasing importance to enable accurate diagnosis and treatment. Immunoassay methods used for drug screening may be inappropriate and lead to false negative results. Conversely, detection of these compounds is possible through use of LC–HRMS and can provide information on the metabolites present after exposure to these drugs.
Development and validation of a simple online‐SPE method coupled to high‐resolution mass spectrometry for the analysis of stanozolol‐N‐glucuronides in urine samples
