A portable voltammetric sensor for presumptive screening of xylazine and ketamine in spiked beverages

Abstract Xylazine and ketamine are psychoactive substances that may be encountered in drug‐facilitated crimes, including their presence in beverages. Rapid and portable screening methods are therefore desirable for preliminary forensic analysis, particularly at the scene of investigation. This study developed a portable voltammetric sensor based on a screen‐printed electrode modified with carbon graphite paste ink (CGP‐ink/SPE) for the presumptive detection of xylazine and ketamine in spiked beverage samples using differential pulse voltammetry (DPV). Electrochemical characterization showed that the oxidation of both xylazine and ketamine was diffusion‐controlled and irreversible. Key experimental parameters, including the volume of CGP‐ink, pH of buffer, and DPV conditions, were systematically optimized to improve electrochemical response. Under optimized conditions, the CGP‐ink/SPE exhibited linear response ranges of 2.0 to 50 μg mL −1 for xylazine and 2.0 to 70 μg mL −1 for ketamine, with a detection limit of 0.62 μg mL −1 and 0.60 μg mL −1 , respectively. The sensor demonstrated excellent repeatability and reproducibility, as well as good recoveries of 98 ± 3% to 103 ± 1% for xylazine and 98 ± 1% to 104 ± 1% for ketamine in drug‐spiked beverage samples. The developed CGP‐ink/SPE provides a simple, rapid, and portable approach for the dual presumptive screening of xylazine and ketamine in beverages and highlights its potential for supporting forensic investigations of drug‐facilitated crimes.