A novel screening workflow for nitazene analogs using LC-MS/MS precursor ion scan acquisition.

Abstract

A persistent problem in the detection of novel psychoactive substances (NPS) is the inability of traditional screening methodologies to rapidly adapt to evolving drug trends. As such, high-resolution mass spectrometry (HRMS) screening methods have gained popularity in recent years for the ability to use non-targeted acquisition to detect a wide variety of compounds without necessarily returning to method development. However, these instruments may be unattainable for some forensic laboratories due to the associated high capital costs. The described method provides an alternative screening method using precursor ion scan (PIS) acquisition on a liquid chromatography tandem mass spectrometry (LC-MS/MS) platform to screen for nitazene analogs. Four ions were evaluated (m/z 72.1, 98.0, 100.1, and 112.1) for D0 analytes and one ion (m/z 104.1) for the metodesnitazene-D4 internal standard. Using a liquid-liquid extraction in whole blood, the method was validated with a 0.5 ng/mL limit of detection and 1.0 ng/mL administrative cutoff. Observed matrix effects did not affect limit of detection and there was no demonstration of carryover or interferences. As a proof-of-concept study, authentic (n = 3) and blind fortified (n = 20) samples were evaluated using this method, which was able to identify all nitazenes with no false negatives or positives. Several nitazenes not initially included in the scope of method development or validation were also presumptively identified. To accommodate this novel instrumental analysis, a workflow is also proposed to assist in the identification of known and emerging nitazene analogs. LC-MS/MS is widely available among forensic laboratories and presents a viable alternative to HRMS screening for nitazene analogs when operated in PIS acquisition, in such cases that HRMS is unavailable for assessing emerging NPS threats.