AOAC 2018 Methods

( d ) Working Stock Solution D .—Pipet 100 µL CBDVA and 100 µL CBGA into a microcentrifuge tube. Vortex to mix for a 1:2 dilution of CBDVA and CBGA. ( e ) Working Stock Solution E .—Pipet 100 µL THCV, CBG, CBC, CBDVA, CBGA, and CBN into a microcentrifuge tube. Dilute with 400 µL reference standard diluent and vortex to mix for 1:10 dilution of THCV, CBG, CBC, CBDVA, CBGA, and CBN. ( f ) Mixed calibration standards .—Prepared according to Table  2018.10A . F. Preparation of Samples ( a ) Homogenization of dried flowers .—( 1 ) Combine contents of flower, ideally up to 5 g or what is available. ( 2 ) Place dried flower in mortar and pestle and add enough liquid nitrogen. ( 3 ) Grind to mesh size of less than 0.5 mm. ( 4 ) Use ground material immediately for analysis. ( b ) Extraction of dried flowers .—( 1 ) Accurately weigh 200 mg ground flower into 50 mL amber centrifuge tube. ( 2 ) Add 25 mL dried flower extraction solvent and vortex for 30 s. ( 3 ) Place in ultrasonicating bath for 15 min and vortex every 5 min. ( 4 ) Centrifuge at 4500 g for 5 min.

( 5 ) Filter with 0.22 µm PTFE filter into amber 2 mL microcentrifuge tube. ( 6 ) Dilute filtered sample into amber HPLC vial with 80% methanol. Typical dilutions are 1:5 or 1:10. ( 7 ) Store at 4°C prior to analysis and analyze within 2 days of preparation. ( c ) Extraction of oils .—( 1 ) Mix oil by inverting 20 times. ( 2 ) Add 50 mg oil into a 50 mL amber centrifuge tube. ( 3 ) Add 10 mL methanol and vortex for 30 s. ( 4 ) Extract in ultrasonicating bath for 15 min and vortex every 5 min. ( 5 ) Centrifuge at 4500 g for 5 min. Table 2018.10B. Gradient conditions for chromatographic separation of cannabinoids Time, min Mobile phase B, % 0 52 8.0 66 8.5 70 13 80 15 80

Figure 2018.10. Chromatographic separation of cannabinoids by LC-UV at 220 nm.

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