As the hemp-related products became available for health purposes, various products from different countries were imported into Korea. To regulate the products, Korean Food and Drug Administration (KFDA) allows the products with a content of less than 10mg/kg of delta-9-tetrahydrocannabinol(△9-THC) and 20mg/kg of cannabidiol (CBD) in hemp seed oils.

In this study, the cannabinoids, △9-THC, CBD, CBN, CBG, and △8-THC were analyzed by LC-MS/MS in 25 hemp seed oil capsules to confirm the products meet the content criteria of △9-THC and CBD. Also, the difference in the ratio of cannabinoids contents between manufacturing countries were investigated. It was noted that the cannabinoid contents were varied by the procuring countries. The freshness of oils was tested in samples by the ratio of [CBN]/[△9-THC]. The result of this study will be utilized to monitor the stability of oils under various conditions of storage in the future.

Twenty-five products of soft capsule-type hemp seed oil (1 domestic product and 24 foreign products) were purchased online. 1g of hemp seed oil was taken from each 25 products, and then mixed with methanol. The mixture was extracted using QuEChERs and then injected into LC-MS/MS. Validations of accuracy, precision, recovery and carry-over were performed.

△9-THC, CBD, CBN, CBG, and △8-THC were well resolved in this condition by LC-MS/MS. The validation results were satisfied with accuracy, precision, recovery, and carry-over.

The contents of △9-THC in 25 samples ranged from 0.155 to 4.333mg/kg, 0.089 to 15.141mg/kg for CBD, 0.028 to 1.783mg/kg for CBN, and 0.021 to 0.355mg/kg for CBG. △8-THC was detected 0.443mg/kg in only one sample. The ratios of [△9-THC]+[CBN]:[CBD] were investigated to see the difference of contents between producing countries and the result revealed big gap from 0.07 to 27.91 in 25 samples. The oils from the United States (n=6) showed the ratio of 8.13 to 27.9, Canada (n=9) 0.18 to 0.35, The Netherlands (n=2) 0.27 and 3.95, 3.95 to 15.65 from New Zealand (n=3), 0.07 and 0.27 from Germany (n=2), 0.21 from Italy (n=1), 0.24 from Finland (n=1), and 0.26 from South Korea (n=1).

The ratio of [CBN]/[△9-THC] was performed to determine the freshness of oils. The range of 4 to 255 was observed in 25 samples indicating a significant difference between samples, but not producing countries. One sample which contained 0.443mg/kg of △8-THC showed much higher CBN than any other samples.

△9-THC, CBD, CBN, △8-THC and CBG were measured in 25 hemp seed oil capsules. All of them met the Korean standard of hemp seed oils for the contents of △9-THC and CBD. △8-THC was detected in only one sample. The ratio of [△9-THC]+[CBN]:[CBD revealed the differences of contents in producing countries showing higher ratio in oils from the USA than Canada. The determination of freshness indicated the importance of storage by the big difference of ratios regardless of producing countries. It was concluded that the stability study is needed to monitor the cannabinoids contents under various conditions.