Characterization of Copper-Phosphine Complexes for the Differentiation of Cannabinoid Isomers Using Electrospray Ionization-Tandem Mass Spectrometry

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This dataset includes Excel spreadsheets with extracted raw data and PowerPoint presentations with screenshots from the Characterization of Copper-Phosphine Complexes for the Differentiation of Cannabinoid Isomers Using Electrospray Ionization-Tandem Mass Spectrometry study that was funded by the National Institute of Justice (Award No. 15PNIJ-24-GG-03858-RESD). The data were derived from the characterization of ten Cu-phosphine complexes in the presence of twenty cannabinoids to assess their ability to differentiate common cannabinoids found in cannabis plant material, as well as ∆9-THC isomers that may be sprayed onto plant material, based on the formation of characteristic precursor or product ions. This data demonstrates the potential of Cu-phosphine ion complexation as a novel method to eliminate CBD interference, establishing the foundation for future research distinguishing illicit marijuana from legal hemp.

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The copper-phosphine complexes were prepared using a synthetic procedure established for [Cu(PPh3)2(ACN)2]BF4. In a typical synthesis, 25.0 mg of [Cu(ACN)4]BF4 (79.5 μmol, 1 equiv.) and 1 equiv. of diphosphine or 2 equiv. of monophosphine ligand were dissolved in 5 mL of ACN at room temperature. The solution was stirred for 5 min, then dried under vacuum to give a white powder or layered with diethyl ether to give well-formed crystals of the desired complex. Complex formation was complete within minutes as judged by NMR, and complexes were isolated in nearly quantitative yield as crude solids or moderate yield (typically 50%) for crystalline material. Crude and crystalline materials gave identical ESI-MS and NMR data across multiple independently prepared batches. Crystalline material suitable for X-ray diffraction could not be obtained for PTA and TTMPP derivatives. The TTMPP system exhibited limited solubility in acetonitrile and was therefore excluded from subsequent analytical studies. All other complexes were characterized by 1 H NMR and 31P NMR spectroscopy, and by X-ray crystallography for complexes of L=PPh3, P(o-tolyl)3, P(mes)3, dppf, RBINAP, Xantphos, and DPEphos. All cannabinoids were analyzed in both acetonitrile and methanol solutions containing Cu-phosphine complexes. Regardless of the solvent composition, all samples utilized for the characterization of Cu-phosphine cannabinoid complexes were prepared with a cannabinoid concentration of 50 ppm (i.e., 50 mg/L) and a Cu-phosphine complex concentration of 15 μM. An Agilent Technologies 6530 quadrupole time-of-flight (Q-TOF) mass spectrometer, coupled to a dual Agilent Jet Stream (AJS) electrospray ionization source, was used for the analysis of all samples in this study. Direct injection with a syringe pump was used to introduce samples into the ionization source at a flow rate of 18 μL/min. Previously established instrumental parameters were implemented as follows: a nebulizer pressure of 40 psi, a 350 ◦C sheath gas with an 8 L/min flow rate, a 300 ◦C drying gas with a flow rate of 8 L/ min, a capillary voltage of 3,500 V, and a nozzle voltage of 1,500 V (DOI: 10.1021/jasms.3c00452). Characterization of all the Cu-phosphine complexes, with and without cannabinoids present, was conducted in positive ionization mode, with a scan range of m/z 40–2,000. For all precursor ions of interest, MS/MS analysis was performed using CID energies of 15, 25, 35, and 45 eV for approximately 30 s per activation energy. For instances where precursor ions exhibited high levels of stability, higher activation energies of 55, 65, and 75 eV were used. The targeted MS/MS analyses were acquired with a 200 ms/spectrum acquisition time and a 4 Da isolation width to encompass peaks representing the monoisotopic mass and the M+2 isotope from the naturally occurring 63Cu and 65Cu isotopes.

Institutions

• Sam Houston State University

  Texas, Huntsville

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Funders

• National Institute of Justice

  United States Department of Justice

  District of Columbia, Washington

  Grant ID: 15PNIJ-24-GG-03858-RESD

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