Solutions for THC Quantitation: Separation of 4 Tetrahydrocannabinol Isomers: Δ6a/10a, Δ8, Δ9, and Δ10 using LC-MS



The cannabis/hemp market continues to grow each year with more states legalizing recreational marijuana, as well as the 2018 Farm Bill removing hemp from the controlled substance list. This bill defines that any cannabis sativa L. strain with a total tetrahydrocannabinol (THC) concentration of 0.3% or less can be considered hemp and not cannabis. Due to this definition, there is an even higher demand to differentiate hemp from cannabis by determining the correct concentration of THC. More recently, there are more instances of adulterated hemp samples with THC variants and a need to fully identify and quantify each of these variants. Currently most laboratories are only monitoring and reporting delta-8 and delta-9 THC. This study develops an LCMS method that separates, identifies, and quantitates delta-8 and delta-9, as well as, delta-10 and delta-6a/10a THC. A Shimadzu LCMS mass spectrometer coupled with a modular Nexera 40 series UHPLC system and a PDA detector was employed for simultaneous analysis of analyte absorbance and compound ionization. Separation of delta-6a/10a THC, delta-8 THC, delta-9 THC, and delta-10 THC was achieved in a single chromatographic run on both a LCMS-2020 single quadrupole mass spectrometer and a LCMS-8045 triple quadrupole mass spectrometer. The LCMS-2020 utilized SIM events to monitor chromatographic separation as well as a scan event to monitor in-source fragmentation for additional analyte confirmation. The LCMS-8045 was used for a more comprehensive cannabinoid analysis allowing for detection of all 4 THC isomers plus 17 other cannabinoids. Both detection methods demonstrated the capability to simultaneously detect, confirm, and quantitate the four different ΔTHC isomers. 

Learning Objectives:

1. Identify the benefit to separating out the different ΔTHC isomers currently being detected in hemp and cannabis samples. 

2. List alternate detection methods for cannabinoids other than UV/Vis and GC-FID. 

3. Discuss method development and results when using LCMS to chromatographically separate and detect ΔTHC isomers. 

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