Simultaneous detection of residual diazepam, ketamine, nimetazepam, and xylazine by high-performance liquid chromatography: application in drug-spiked beverages for forensic investigation

Abstract

Drug facilitated crimes (DFCs) involve the incapacitation of a victim due to the administration of a single drug or a combination of drugs. Traditionally, biological samples are collected from a victim and analysed to provide evidence of drug administration. However, the rapid metabolism of many such drugs together with delays in analysis can compromise the detection of such substances. This study investigated the capacity of a high-performance liquid chromatography (HPLC) method to detect, simultaneously, four sedative-hypnotic drugs, diazepam, ketamine, nimetazepam, and xylazine, recovered from spiked beverages. A HPLC method was developed and validated and was then applied to the detection of the target substances in simulate forensic case scenarios. The four target substances were well-separated (correlation coefficient, 0.99) while the limit of detection was determined to be 39.1 ng/mL (xylazine), 78.1 ng/mL (diazepam and nimetazepam), and 156.3 ng/mL (ketamine), respectively. Precision (%RSD <7.8%) and accuracy (95.3%–106.6% recovery) were also acceptable and good recoveries were achieved from the drug-spiked samples. In conclusion, a simple and direct HPLC method was successfully developed and applied to the recovery of sedative-hypnotic drugs from spiked beverages.