Simultaneous quantitative analysis of 39 common toxicological drugs for increased efficiency in an ante- and...

A novel forensic method was developed to quantitate 39 drugs of toxicological interest for ante-mortem and postmortem analysis. This method was created to combine and replace four existing quantitation methods as well as add three additional compounds of interest and serves to drastically increase the efficiency of the criminalists and reduce the case backlog. The method is currently applied to ante-mortem blood, postmortem blood, urine, liver, brain, and gastric contents.

The extraction was performed by using a protein precipitation and DPX WAX-S tips with analysis on a Waters® i-class Acquity ultra-performance liquid chromatography with a Phenomenex Kinetex® Column (1.7 µm Biphenyl Å, 2.1 ×100 mm) followed by a Waters® XeVo-TQS tandem mass spectrometer using positive electrospray ionization in multiple reaction monitor mode. The sample volume required for analysis was 0.5 mL, or 0.5 g, an improvement from 4 mL when performing previous methods utilized in the laboratory.

The improved method incorporated the 2017 recommended cut-offs for toxicological investigation of driving under the influence of drugs and was validated following the SWGTOX and ANSI/ASB guidelines of method validation. The advantages of analyzing low volume cases and/or detecting drugs previously outside the laboratory's scope of analysis, (such as gabapentin, pregabalin and baclofen) will be presented in two case studies.

The multi-drug quantitation method allowed for the analysis of 39 drugs including a hydrolysis step, if needed, with only 0.5 mL or 0.5 g of sample. The method condensed two previously un-validated quantitative methods and two additional qualitative methods, which detected many commonly seen drugs, all into a single method. Three additional analytes of interest, gabapentin, pregabalin and baclofen, which it had previously been unable to detect, were added to the new method. The added benefit of these new drugs added both the coroner's investigators in cause of death determination and driving under the influence of drugs investigation especially with the high prevalence of gabapentin.