A method for the structural determination of cannabichromene metabolites by mass spectrometry

Ready identification of hydroxy metabolites of cannabichromene (CBC) by mass spectrometry of their trimethylsilyl derivatives is prevented by the dominant fragmentation to give a substituted chromenyl ion; this suppresses ions diagnostic of the position of metabolic hydroxylation. To overcome this difficulty, metabolites were hydrogenated over a rhodium/alumina catalyst to reduce the double bond responsible for chromenyl ion formation and to redirect the fragmentation to the site of metabolic attack. This resulted in the production of abundant diagnostic fragment ions enabling all monohydroxy-CBCs to be readily identified.