Differentiation of Hemp and Marijuana Through Ion Complexation with Copper Phosphine Complexes

The enactment of the Agricultural Improvement Act of 2018, commonly referred to as the Farm Bill, altered how suspected marijuana samples must be analyzed within forensic laboratories given that this legislation enables hemp to contain up to 0.3% ∆9-tetrahydrocannabinol (∆9-THC) on a dry weight basis. Currently, gas chromatography-mass spectrometry (GC-MS) is the primary technique used for the differentiation of hemp and marijuana based on either a semi-quantitative or quantitative determination of the ∆9-THC content. However, there are growing concerns about the potential conversion of cannabinoid isomers to ∆9-THC due to the elevated temperatures of the GC inlet liner and the presence of emerging ∆9-THC positional isomers. Alternatively, liquid chromatography (LC) separations can be combined with ultraviolet (UV) or mass spectrometry (MS) detection, but the selectivity is dictated entirely based on the retention time due to indistinguishable UV spectra and full scan/product ions spectra for isobaric cannabinoids, such as ∆9-THC positional isomers. 

This proposal will develop and validate LC-MS/MS and LC-PDA-MS analytical methods for the differentiation of hemp and marijuana using semi-quantitative and quantitative analysis of ∆9-THC, including in the presence of emerging ∆9-THC positional isomers, through ion complexation with copper phosphine complexes. Subtle differences in binding affinities between ∆9-THC positional isomers lead to the formation of unique full scan and/or product ion spectra that provide enhanced mass spectral selectivity towards ∆9-THC positional isomers, as well as enable the detection of both neutral cannabinoids and acidic cannabinoid precursors, such as tetrahydrocannabinol acid (THCA), in positive ionization mode. Providing the seized drug community with a method for the differentiation of hemp and marijuana, including differentiation of ∆9-THC positional isomers through unique mass spectral features for enhanced certainty, will directly address the need for alternative techniques for the analysis of cannabis and establish a foundation for the analysis of cannabis products.

The dissemination of the research results will include a series of peer-reviewed manuscripts that will describe the selectivity achievable through ion complexation with copper phosphine complexes and validated analytical methods for the semi-quantitative and quantitative differentiation of hemp and marijuana, including the differentiation of emerging ∆9-THC positional isomers. The results will also be disseminated through relevant national conferences such as the Federation of Analytical Chemistry and Spectroscopy Societies (SciX), the American Academy of Forensic Sciences (AAFS), and the American Society for Mass Spectrometry (ASMS), as well as semi-annual and final progress reports to NIJ. CA/NCF