The analytical challenges presented by synthetic cannabinoids and cathinones (novel psychoactive substances, (NPS)) include the lack of reference materials and the rapid appearance of new synthetic variants.  Consequently, the traditional forensic identification tools cannot keep pace with the flow of new structures and compounds appearing in physical and toxicological evidence.  The structural similarity among families of NPSs may afford tentative identifications or classifications, but laboratories often must report inconclusive results and new variants may go unrecognized for some time.  This can have implications in law enforcement as well as public health given the range of toxic effects being associated with ingestion of many of these drugs. <br/>A long-term goal of this project is to develop algorithms capable of classifying novel synthetics based on structure and to create similarity measurements that can characterize new NPSs as compared to existing and known structures.  However, before this goal can be achieved, verified and validated data and figures of merit must be established for the necessary measurands: retention time/retention index and mass spectra, specifically relative ion abundances.  There is no point attempting to build a quantitative predictive model for mass spectral identification without knowing how much relative ion abundances vary across time and instruments.  Reported here are results to date of a selected group of NPS compounds (JWH’s, UR-144, and cathinones as well as amphetamine) analyzed using three different GC/MS systems over time.  All instruments are models commonly used in forensic science laboratories.  Variables recorded included tuning conditions, elapsed time since tuning, time since inlet change, time since column maintenance, and all relevant instrumental settings.  The level of instrument use varied among the three systems from extensive shared facility use to isolated use for this project. Kovats retention indices were calculated relative to a C7-C40 alkane ladder.  DB-5 columns of different lengths were used.  Sample concentrations were at low (close to the method detection limit), mid-range, and high concentrations.  Ion repeatability and reproducibility were determined based on the ratios of the twenty most abundant ions in the spectrum.  Initial estimates of uncertainty and reproducibility, between instruments and within a single instrument as a variation of time, will be presented.

Evaluation of the repeatability, reproducibility, and uncertainty of retention indices and electron impact spectra of selected novel psychoactive substances

254th National Meeting (2017)

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