Abstract

Empirical data regarding dynamic alterations in illicit drug supply markets in response to the COVID-19 pandemic, including the potential for introduction of novel drug substances and/or increased poly-drug combination use at the ‘street’ level, i.e., directly proximal to the point of consumption, is currently lacking. Here, a high-throughput strategy employing ambient ionization-mass spectrometry is described for the trace residue identification, characterization and longitudinal monitoring of illicit drug substances found within >6,600 discarded drug paraphernalia (DDP) samples collected during a pilot study of an early warning system for illicit drug use in Melbourne, Australia from August 2020-February 2021, while significant COVID-19 lockdown conditions were imposed. The utility of this approach is demonstrated for the de novo identification and structural characterization of beta-U10, a previously unreported naphthamide analogue within the ‘U-series’ of synthetic opioid drugs, including differentiation from its alpha-U10 isomer without need for sample preparation or chromatographic separation prior to analysis. Notably, beta-U10 was observed with 23 other drug substances, most commonly in temporally distinct clusters with heroin, etizolam and diphenhydramine, and in a total of 182 different poly-drug combinations. Longitudinal monitoring of the number and weekly ‘average signal intensity’ (ASI) values of identified substances, developed here as a semi-quantitative proxy indicator of changes in availability, relative purity and compositions of street level drug samples, revealed that increases in the number of identifications and ASI for beta-U10 and etizolam coincided with a 50% decrease in the number of positive detections and an order of magnitude decrease in the ASI for heroin.

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