Clandestine heroin laboratories have been a feature of the Malaysian illicit drug scene since soon after the abuse of heroin emerged in 1972. The first few clandestine heroin laboratories which synthesised heroin via the acetylation of imported morphine were uncovered in 1973 and 1977. By the mid-1980s, this type of laboratory was replaced by heroin-cutting laboratories whereby imported high-grade heroin was cut to street heroin. This was to meet the rising demand for the drug owing to the rapid escalation of the number of drug users. Over the years, the most significant change in the composition of the street heroin is the decrease in its purity from 30%-50% to 3%-5%. Caffeine has remained the major adulterant and chloroquine is detected in virtually all recent seizures.
Drugs-facilitated crimes (DFCs) involve the incapacitation of victims under the influence of drugs. Conventionally, a drug administration act is often determined through the examination of biological samples; however, dry residues from any surface, such as drinking glass if related to a DFC could be a potential source of evidence. This study was aimed to establish an attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy coupled with chemometrics for the determination of spiked sedative-hypnotics from dry residues of a drug-spiked beverage. In this study, four sedative-hypnotics, namely diazepam, ketamine, nimetazepam, and xylazine were examined using ATR-FTIR spectroscopy. Subsequently, the ATR-FTIR profiles were compared and decomposed by principal component analysis (PCA) followed by linear discriminant analysis (LDA) for their detection and discrimination. Visual comparison of ATR-FTIR profiles revealed distinct spectra among the tested drugs. An initial unsupervised exploratory PCA model indicated the separation of four main sedative-hypnotics clusters, and the proposed PCA score-LDA model had allowed for a 100% accurate classification. Discrimination of sedative-hypnotics from a dry beverage previously spiked with these drugs was also possible upon an additional extraction procedure. In conclusion, ATR-FTIR coupled with PCA score-LDA model was useful in detecting and discriminating sedative-hypnotics, including those that had been previously spiked into a beverage.
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.