Three brands (brand# 1, 2 and 3) of hemp seeds were purchased from local supermarkets in Toronto, Canada, and were used as such in the laboratory experiments. All experiments, including extractions and analyses, were conducted under the appropriate Controlled Drugs Substances Dealer License granted to University Health Network. For ultra performance liquid chromatography (UPLC) analysis, HPLC-grade methanol and MilliQ ® water were used for the preparation of the eluents. A Biotage ® Initiator microwave was employed for all microwave-related experiments. Sample solutions were analyzed on a Waters ® ACQUITY UPLC H-Class System equipped with Quaternary Solvent Manager, Sample Manager FTN, and Acquity UPLC ® BEH column (2.1×50 mm, C18, 1.7 μm). A Waters MS 3100 mass spectrometer was used to monitor the samples in both the positive (ES+) and negative (ES−) modes. The injection plate and column were maintained at 15°C and 40°C, respectively. Cerilliant ® standards for Δ 9 -THC, Δ 9 -tetrahydrocannabinolic acid (Δ 9 -THCA), cannabidiolic acid (CBDA), and CBD were purchased from Sigma-Aldrich ® as Certified Reference Standards in the form of 1.0 mg/mL solutions in methanol or acetonitrile.
2. Sonication. Hemp seeds (1 g) were macerated, reweighed, and then transferred to a beaker. The macerated seeds were suspended in ethanol (26 mL), and the suspension was sonicated for 20 min after which the solvent was decanted. The sonication was repeated two additional times, collecting the solvent by decantation, refilling with an equivalent amount of solvent, and a 10-min break between each sonication session. All decanted solvent fractions were combined and filtered on a pad of Celite (1 g) and activated carbon (0.25 g). The solids were washed with additional solvent and concentrated to dryness under reduced pressure at 25°C to obtain a sticky resin (yield: 23–40%).
Commercial hemp seeds are marketed for their high nutritional values, but due to their relationship to Cannabis spp. of plants, there is a potential for the presence of phytocannabinoids in these seeds. By regulation, total amount of Δ 9 -THC (whether in its acid form, Δ 9 -THCA, or as neutral Δ 9 -THC) must be less than 10 μg/g of hemp seeds (10 ppm) in Canada, and similar regulations exist in other countries where hemp seeds are legal. Hemp seeds from three brands in local supermarkets were purchased and brought to the laboratory. Each brand of hemp seeds was subjected to four different extraction protocols, and each protocol was repeated thrice to account for any variability due to the extraction procedures and associated errors. In total, 36 extracts were obtained from the three brands and analyzed using UPLC-mass spectrometry to quantify the two major phytocannabinoids, Δ 9 -THC and CBD. We expected the quantity of Δ 9 -THC to be within the regulation limits and CBD to be in relatively higher quantities, as one would expect in hemp seeds. As it is common in the Cannabis spp. plants, majority of phytocannabinoids such as Δ 9 -THC and CBD exist in their carboxylic acid precursor forms, Δ 9 -THCA and CBDA ( Fig. 1 ). Subjecting the extract or resin to high degree of temperature converts these acid precursors into decarboxylated forms, Δ 9 -THC and CBD. However, we calculated the total Δ 9 -THC equivalency (including Δ 9 -THCA and Δ 9 -THC found in each extract) to assess the total concentrations; similar procedure was used for the total concentration of CBD.
Conclusion: Careful consideration of the extraction method is very important for the measurement of cannabinoids in hemp seeds.
Materials and Methods
All extracts were analyzed for the concentrations of Δ 9 -THC, Δ 9 -THCA, CBDA, and CBD. Thus, concentration standard curves for Δ 9 -THC, CBD, Δ 9 -THCA, and CBDA were generated using the respective cannabinoid standards of various concentrations and internal standard (Supplementary Fig. S1). These standard curves were used to estimate the concentrations of the above analytes in the extracts. Lower limits of detection for Δ 9 -THC, Δ 9 -THCA, CBD, and CBDA are 1.0, 1.0, 2.5, and 1.0 ng/mL, respectively, and the lower limits of quantitation are 2.5, 2.5, 5.0, and 2.5 ng/mL, respectively.
It’s never been easier to grow your own marijuana plant and all you need is a list of the best seed banks to get started.
13 Best Seed Banks That Ship to the USA (and beyond)
You could send Bitcoin, Paypal funds, or even a money order through the mail and get your seed within a couple of weeks. Shipping is same-day and faster-than-average, with a dedicated customer support line.
7. Rocket Seeds – Fastest Delivery for Cannabis Seed Banks