[Design and application of special solid phase extraction column for three cannabinol compounds in hemp]

Area of Science:

• Analytical Chemistry
• Phytochemistry
• Forensic Science

Background:

• Hemp contains valuable cannabinoids like cannabidiol (CBD), cannabinol (CBN), and Δ9-tetrahydrocannabinol (THC).
• Accurate quantification of these cannabinoids is crucial for determining hemp's properties and applications.
• Hemp extracts contain impurities (pigments, sugars, lipids, metal ions) that interfere with analytical methods like UHPLC.

Purpose of the Study:

• To develop and validate a specialized solid phase extraction (SPE) column for efficient removal of hemp extract impurities.
• To optimize chromatographic conditions for the simultaneous determination of CBD, CBN, and Δ9-THC.
• To assess the efficacy of the SPE method in terms of impurity removal rates and cannabinoid recovery.

Main Methods:

• A mixed-adsorbent SPE column was prepared using neutral alumina, magnesium silicate, and graphitized carbon black.
• Hemp flowers and leaves were extracted using an ethyl acetate/methanol mixture.
• Ultra-high performance liquid chromatography (UHPLC) with optimized conditions (Eclipse Plus C18 column, specific mobile phase, 210 nm detection) was used for cannabinoid analysis.

Main Results:

• The SPE column achieved high removal rates for pigments (up to 99.2%), total sugar (98.5%), total fatty glyceride (96.9%), and metal ions (85.4%).
• Excellent recoveries for CBD (98.9%), CBN (95.7%), and Δ9-THC (99.2%) were obtained after SPE.
• Optimized UHPLC method provided separation within 10 minutes, with good linearity (R² > 0.998), low detection limits (0.38-0.53 μg/L), and acceptable recoveries (90.3%-96.9%) and RSDs (2.2%-8.0%).

Conclusions:

• The developed SPE column effectively purifies hemp extracts, removing significant impurities.
• The optimized UHPLC method allows for sensitive and accurate determination of CBD, CBN, and Δ9-THC.
• This integrated SPE-UHPLC approach is well-suited for routine analysis of major cannabinoids in hemp.