Analysis of Synthetic Cannabinoids in Seized Drugs by High-Resolution UHPLC/MS and GC/MS
The practice of synthesizing novel drugs with slight chemical structure modifications is commonplace for controlled substances. These “designer drugs” are made with the intent of circumventing controlled substance laws, and they present a major challenge to law enforcement laboratories charged with investigating the nature of seized materials. Synthetic cannabinoids represent one of more than twenty classes of designer drugs, under federal control in the United States. Figure 1 shows the chemical structure of Δ9-THC, the principal active component of cannabis, and two representative structures from the group of 23 analyzed in this study.
The Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) sets standards for analysis of seized drugs. Under this guidance, various analytical methodologies are grouped into three categories (designated by SWGDRUG as categories A, B and C) according to technical specificity. Combinations of techniques or hybrids that might be considered include mass spectrometry (MS) (Category A) with a separation technique from category B, such as liquid chromatography (LC) or gas chromatography (GC). However, positive results should be reported only if confirmed by two independent techniques, where hybrid approaches count as a single measurement.
A set of 23 synthetic cannabinoids were analyzed by UHPLC/ MS and GC/MS to compare identification abilities. High Resolution (HR) LC/MS offers the advantage of molecular formula determination, while GC/MS provides structurallysignificant fragment ions. Chromatographic retention times for the two approaches were compared using TIBCO Spotfire® software to perform principle component analysis (PCA). This analysis demonstrated that retention times were not correlated between the two analytical techniques. This is important when considering regulatory guidance concerning appropriate choices for methodologies applied to the screening and confirmation of seized drug samples