Investigating the capability of UA-DLLME and DART-HRMS in the analysis of benzodiazepines in whole human blood

Benzodiazepine (BZD) misuse has increased in the last decade, making its occurrence in criminal cases more commonplace. The detection of BZD in complex biological samples is challenging since they are usually found in small concentrations, requiring the development of sensitive and fast-to-execute methods. In this study, the application of direct analysis in real time – high-resolution mass spectrometry (DART-HRMS) was evaluated in the detection of 10 benzodiazepines (diazepam, oxazepam, chlordiazepoxide, temazepam, alprazolam, flunitrazepam, bromazepam, clonazepam, lorazepam, and midazolam) in ante and postmortem blood samples. Moreover, an ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) approach was developed by full factorial design as a clean-up step before the DART-HRMS analysis. DART-HRMS was capable of qualitative detection of all evaluated BZD in raw antemortem blood samples at concentrations as low as 10 µg mL⁻¹. The UA-DLLME DART-HRMS approach was linear for the 10 BZD in the range of 1 to 10 µg mL⁻¹, with recoveries ranging from 78.5 to 119.5 %, a precision lower than 36 % at 1 µg mL⁻¹, and limits of detection varying between 0.25 and 0.50 µg mL⁻¹. Moreover, the UA-DLLME DART-HRMS method was efficiently applied to postmortem blood samples from criminal cases, enabling the detection of BZD. The developed method facilitated the analysis of 10 BZD in ante and postmortem blood samples, offering a quick sample extraction that linked to the DART-HRMS can be used as a fast and reliable triage method for regulatory screening purposes and could be readily integrated into routine forensic analysis workflows in a high throughput manner.