Development and validation of a liquid chromatography tandem mass spectrometry method for the analysis of 53 benzodiazepines in illicit drug samples

An LC-MS/MS method for the analysis of 53 benzodiazepines, including various designer benzodiazepines, was developed. The developed method was applied to a total of 79 illicit street drug samples collected in Chicago, IL. Of these samples, 68 (84%) had detectable amounts of at least one benzodiazepine. Further, of the 53 benzodiazepines included in the developed method just 14 were measured in samples. Clonazolam, a potent designer benzodiazepine and derivative of clonazepam, was the most frequently measured benzodiazepine in 63% of samples and was measured in the highest concentrations. Other benzodiazepines measured in more than 10% of samples included clonazepam, alprazolam, flualprazolam, and oxazepam. Mixtures of benzodiazepines were frequently measured in samples, with just 24% of samples containing just one benzodiazepine. To determine the response of benzodiazepines on a rapid, point-of-use drug checking tool, all 53 benzodiazepine standards were screened on a lateral flow immunoassay benzodiazepine test strip. Sixty eight percent of standards gave a positive BTS response at a concentration of 20 µg/mL, demonstrating BTS have response to a wide variety of benzodiazepines, including many designer benzodiazepines. A comparison of this data to previous data reported for the same samples demonstrated all samples containing a benzodiazepine also had an opioid present, with fentanyl being present in 94% of benzodiazepine samples. These results highlight high rates of polysubstance drug presence in Chicago, IL illicit drug samples, posing an increased risk of drug overdoses in people who use drugs.