Rapid Determination of Methamphetamine, Methylenedioxymethamphetamine, Methadone, Ketamine, Cocaine, and New Psychoactive Substances in Urine Samples Using Comprehensive Two-Dimensional Gas Chromatography

<b>Background/Objectives:</b> This study evaluates the applicability of a comprehensive two-dimensional gas chromatography-flame ionisation detection (GC×GC-FID) approach for the simultaneous determination of 12 underivatised psychoactive drugs, including new psychoactive substances, that comprised of amphetamine, methamphetamine, mephedrone, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, α-pyrrolidinovalerophenone, <i>n</i>-ethylpentylone (ephylone), norketamine, ketamine, 3,4-methylenedioxypyrovalerone, methadone, and cocaine. <b>Methods:</b> Separation was effected using a non-polar first dimension (¹D) and a polar second dimension (²D) column, demonstrating an improved separation of drug compounds compared to a polar/non-polar column configuration. Interference-free baseline separation of all psychoactive compounds in a urine matrix was achieved within 8 min. The GC×GC-FID method was validated according to the guidelines defined by Standard Practices for Method Validation in Forensic Toxicology. <b>Results:</b> The calibration curves for the 12 psychoactive drugs were well correlated (r² > 0.99) within the concentration ranges of 50-1500 ng mL^-1. Detection limits of 10-20 ng mL^-1 were obtained, and good repeatability and reproducibility (CV < 11.4%) were attained for retention times and peak areas. Method recoveries for the small-scale solvent extraction procedure ranged from 96.9 to 114.5%, and bias was between -3.1% and 14.5%. <b>Conclusions:</b> The validated approach was successfully applied for the determination of these illicit compounds in spiked urine samples of different concentrations, highlighting its potential for rapid forensic drug screening.