LC-MS Method Development and Optimization for Small Drug Analysis in Urine

Abstract

Both amphetamine and methamphetamine are considered to be illegal chemicals, and hence, the purchase, possession, and use of these drugs is forbidden in many nations. Within the fields of forensic and clinical toxicology, there has been a recent uptick in the detection and quantification of illicit substances within urine samples. Objective: To detect and quantify both drugs in urine samples utilizing caffeine as an internal standard with an optimized liquid-liquid extraction procedure. Methods: An alternative rapid and efficient method of liquid chromatography – electron spray ionization – Tandem mass spectrometry (LC – ESI – TMS) was developed and optimized. The chromatographic separation was carried out using an isocratic high-performance liquid chromatography (HPLC) system, and the eluent that was applied was a mixture of 20% acetonitrile and 80% buffer with a pH of 2.6 that included 10mM ammonium acetate and 0.1% trifluoroacetic acid. The run duration was 9 minutes, and the detection was accomplished at 210 nm with a flow rate of 1 mL/min utilizing triple quadruple MSMS to validate ionic transitions following direct infusion and fragmentation of analytes. Results: An excellent linearity was seen in the calibration curves of amphetamine and methamphetamine in urine samples across the concentration range of 0-10 mg/L, with a regression coefficient of 0.91 and 0.97, respectively, for each of these substances. Conclusions: More compounds are able to be identified in urine as chromatographic techniques, such as high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS), continue to improve in terms of their sensitivity