Reference standards (Δ9-THC, 11-OH-THC, CBD, and cannabinol [CBN]) and isotopically labeled internal standards (THC-d3, 11-OH-THC-d3, CBD-d3, CBN-d3) were purchased from Cerilliant (Round Rock, TX). BondElut® certify (Varian, Lake Forest, CA) C-18 cartridges were used for solid-phase extraction. HPLC grade water, 0.1% formic acid in acetonitrile (ACN), and methanol (MeOH) were purchased from Fisher Scientific. Reagent grade ammonium formate and pure sodium hydroxide pellets were purchased from Sigma-Aldrich.
We followed the Wei et al saponification-solid-phase extraction method for sample clean up and extraction with minor modifications.15 (link)Chromatographic separation was achieved on reverse-phase C-18 column (MAC-MOD Ace 5 C-18, 15cm · 2.1mm). The mobile phase consisted of 5 mM ammonium formate in 0.05% formic acid (Solvent A) and ACN in 0.1% formic acid (Solvent B). A gradient elution was performed over 15 minutes at a flow rate of 200 μL/min. Retention times for 11-OH-THC, CBD, THC were 9.35, 10.62, and 11.70 minutes in positive ion mode, respectively. Quantitation of THC, 11-OH-THC, and CBD and isotopically labeled internal standards was achieved on a triple quadrupole mass spectrometer (API-4000, AB Sciex) in positive ion mode. CBN and CBN-d3 were detected in negative ion mode.
We followed the Wei et al saponification-solid-phase extraction method for sample clean up and extraction with minor modifications.15 (link)Chromatographic separation was achieved on reverse-phase C-18 column (MAC-MOD Ace 5 C-18, 15cm · 2.1mm). The mobile phase consisted of 5 mM ammonium formate in 0.05% formic acid (Solvent A) and ACN in 0.1% formic acid (Solvent B). A gradient elution was performed over 15 minutes at a flow rate of 200 μL/min. Retention times for 11-OH-THC, CBD, THC were 9.35, 10.62, and 11.70 minutes in positive ion mode, respectively. Quantitation of THC, 11-OH-THC, and CBD and isotopically labeled internal standards was achieved on a triple quadrupole mass spectrometer (API-4000, AB Sciex) in positive ion mode. CBN and CBN-d3 were detected in negative ion mode.
