Finding evidence at a crime scene: Sensitive determination of benzodiazepine residues in drink and food paraphernalia by HPLC-HRMS/MS

Benzodiazepines are often used in drug-facilitated crimes, including robberies and sexual assaults, because their administration can make victims more compliant. The development of methods to assess the presence of these substances in connection with criminal acts is therefore crucial. The proposed method involved the use of single-use disposable swabs for the collection of drug residues on the surface of different items such as plastic or ceramic cups, drinking glasses and metal teaspoons or other items, which are commonly found at crime scenes. The extracts obtained from the swabs were then cleaned up and concentrated by means of dispersive liquid-liquid microextraction (dLLME); this procedure provided a high enrichment factor and consequently an improved sensitivity, which is particularly useful in cases where items may have been accidentally or deliberately cleaned before collection. Qualitative and semi-quantitative analysis was performed by means of an HPLC-HRMS/MS system. Two different precursor ion/fragment ion transitions were selected for each analyte to ensure a satisfactory number of identification points. The presented method was validated according to international guidelines and then applied to a real case, in which some dirty and soapy glasses were the only relevant evidence to evaluate the possible covert drugging of a rape victim.