Determination of Dextromethorphan and Dextrorphan in Urine Using Bar Adsorptive Microextraction Followed by Gas Chromatography–Mass Spectrometry Analysis

Over the past few years, the misuse of medications has progressively increased, posing a significant public health concern. This study proposed the development and validation of an alternative and greener analytical method for the determination of dextromethorphan (DXM) and its major metabolite, dextrorphan (DXO), in urine matrices using bar adsorptive microextraction (BAμE), followed by gas chromatography–mass spectrometry (GC-MS) analysis. Under optimized experimental conditions, average recoveries of 96.3% and 80.4% were achieved for DXM and DXO, respectively. The analytical limits obtained were 0.016 μg/mL for the limit of detection and 0.054 μg/mL for the limit of quantification. The working range was from 0.06 μg/mL to 2.0 μg/mL, with linearity for both compounds by determination coefficients (r² > 0.99) and the goodness-of-fit and lack-of-fit tests. Intra-day precision and trueness yielded values below 8.77% and 16.28%, respectively, for both compounds. Inter-day precision and trueness values were below 7.67% and 9.73%, respectively. The application to 26 urine samples allowed the quantification of both compounds, with concentrations ranging from 0.06 to 3.21 μg/mL for DXM and 0.06 to 8.88 μg/mL for DXO. The method proved to be effective, selective, sensitive, simple, and cost-effective in the detection and quantification of DXM and DXO, reinforcing its applicability and feasibility in various laboratory contexts.