A liquid chromatography electrospray ionization tandem mass spectrometry method for quantification of up to eighteen...

A LC-ESI/MS/MS method was developed for quantification of up to eighteen cannabinoids, the maximum number published so far. A thorough study of published LC-ESI/MS/MS methods using triple quadrupole mass spectrometers revealed a possible misconception that multiple reaction monitoring (MRM) was able to definitively differentiate structural isomers of cannabinoids, especially Δ⁸-/Δ⁹-tetrahydrocannabinol (THC), which explained why many of those methods were developed for a limited number of cannabinoids, as small as two, and did not include Δ⁸-THC. In this study, the use of a quadrupole time-of-flight (QTOF) mass spectrometer for targeted analysis indicated that MRM could not definitively distinguish structural isomers of Δ⁹-THC, with a possible exception of cannabicyclol (CBL) for less accurate quantification, so their baseline separation was essential for their accurate quantification. After the developed method was successfully validated according to the ISO 17025 guidelines, it was further applied for the analysis of eighteen hemp-derived products, including drinks, water-soluble oils, topical serum, body lotion, face cream, lip balm, gummies, hard candy, coffee, snacks, and pet treats. The LOQ was 0.00008% (w/w) for drinks with the analysis of 12.5 mg/mL extracts, while the LOQ was 0.008% (w/w) for other samples because 125 μg/mL extracts were analyzed due to higher content of cannabinoids in non-drink samples. For the first-time, extraction recovery and matrix effect were tracked in real-time for each sample being analyzed, obtaining 92.9-106.3% and 91.3-120.2% in triplicate measurements, respectively, by spiking abnormal cannabidiol (ACBD), a cannabinoid not naturally present in hemp, into each sample before extraction and ACBD-d₃ into each sample after extraction.