This article describes the application of indirect quenching of cyanine dye (Cy5) in order to detect nitrated benzodiazepines, which some sex offenders have placed in drinks of unsuspecting victims in order facilitate a subsequent sexual assault through a sedative effect and anterograde amnesia in the victim.
In the investigations of drug-facilitated sexual assaults (DFSA), evidence of nonconsensual sex may depend on the analysis of small amounts of liquid left over in an empty container. A screening tool for such samples should provide rapid results and accommodate small sample volumes. Because of its relatively small size and minimal sample required, chip-based capillary electrophoresis is a technique that can meet these requirements; however, drugs and other small molecules must be derivatized to permit detection. Although chip-based derivatization schemes have been developed to detect primary and secondary amines, these techniques are not generally applicable to benzodiazepines. Instead, indirect detection techniques can be used. A fluorescent dye is added to the buffer, and detection occurs due to quenching or displacement of the background signal. This article reports on the development of an indirect fluorescence assay for nitrated benzodiazepines used in DFSA. This technique was initially used by Bailey and coworkers for the detection of nitro-based explosives. The procedure involves the fluorescence quenching of cyanine dye by the organic nitrate groups. Certain benzodiazepines used in DFSA also contain accessible nitro groups and can be detected. In the current analysis, micellar electrokinetic chromatography was used with a cyanine dye (Cy5) for indirect laser-induced florescence detection. An organic modifier was added to permit resolution of flunirazepam, desmethylflunitrazepam, clonazepam, and nitrazepam in less than 2 min. This method is suitable for use as a screening technique for beverages that contain benzodiazepines. 2 figures, 2 tables, and 24 references