A Quantitative 1H NMR Method for Screening Cannabinoids in CBD Oils

Abstract

Toxicologically relevant levels of the psychoactive ∆9-tetrahydocannabinol (∆9-THC) as well as high levels of non-psychoactive cannabinoids potentially occur in CBD (cannabidiol) oils. For consumer protection in the fast-growing CBD oil market, facile and rapid quantitative methods to determine the cannabinoid content are crucial. However, the current standard method, i.e., liquid chromatography combined with tandem mass spectrometry (HPLC-MS/MS), requires a time-consuming multistep sample preparation. In this study, a quantitative nuclear magnetic resonance spectroscopy (qNMR) method for screening cannabinoids in CBD oils was developed. Contrary to the HPLC-MS/MS method, this qNMR features a simple sample preparation, i.e., only diluting the CBD oil in deuterochloroform. Pulse length-based concentration determination (PULCON) enables a direct quantification using an external standard. The signal intensities of the cannabinoids were enhanced during the NMR spectra acquisition by means of multiple suppression of the triglycerides which are a major component of the CBD oil matrix. The validation confirmed linearity for CBD, cannabinol (CBN), ∆9-THC and ∆8-THC in hemp seed oil with sufficient recoveries and precision for screening. Comparing the qNMR results to HPLC-MS/MS data for 46 commercial CBD oils verified the qNMR accuracy for ∆9-THC and CBD, but with higher limits of detection. The developed qNMR method paves the way for increasing the sample throughput as a complementary screening before HPLC-MS/MS.

Selective Preparation and High Dynamic-Range Analysis of Cannabinoids in “CBD Oil” and Other Cannabis sativa Preparations

“…For the analysis of complex matrices such as Cannabis preparations, qNMR has found increased use in measuring the amounts of individual small-molecule components. ,,, In this context, complexity refers to the number of different chemical structures, the variability of the constituent polarities based on functional groups, the range of constituent molecular mass, and the dynamic range of constituent abundance. Interfering compounds are a challenge to all forms of quantitation; therefore, various sample preparation methods have been developed to “clean-up” samples before analysis.…”

“…Fraction characterization was performed by quantitative 1 H NMR (qHNMR) as the primary quantitation method. Besides structural characterization, NMR has been used previously for both the quantitation of cannabinoids in extracts and the creation of cannabinoid profiles of crude extracts. − Notably, qNMR provides a means of quantitation that is independent of response factors. Here, qHNMR accompanied by HiFSA ( 1 H iterative full spin analysis) was employed for the unambiguous structural dereplication of chemical constituents and in order to afford high reproducibility for future use of the chromatographic and structural data generated.…”

NMR Spectroscopy Applied to the Metabolic Analysis of Natural Extracts of Cannabis sativa

“…It is worth noting that the NMR technique has been proven to be a reliable and powerful tool for the quantification of different natural products and, especially in recent years, has also been successfully applied to the quantification of CBD and other cannabinoids directly on hemp extracts coming from different cultivars using both the 1 H and 13 C qNMR methodologies. [ 40 , 44 , 68 , 69 , 70 , 71 ]. Quantitative 1 H-NMR is the most widely used method in the quantification of natural extracts and has been shown to have a good level of accuracy and reproducibility.…”

Absence of Relevant Thermal Conversion of Cannabidiol (CBD) to Tetrahydrocannabinol (THC) in E-Cigarette Vapor and Low-THC Cannabis Smoke

“…From the condensate methanol mixture, 600 µl were transferred to a NMR tube for the quantification of ∆ 9 -THC and CBD in a Bruker 400 MHz Ultrashield NMR spectrometer (Bruker, Rheinstetten, Germany). The NMR method was previously described in detail 8 . As a reference sample, the same amount of unvaporized e-liquid was dissolved in 2 ml of MeOD and also prepared for measurement.…”