AOAC 2018 Methods

the individual calibration standards should be within ± 20 % of the theoretical concentrations to be acceptable for quantification. (e) Positive and Negative Control. —Analyze a procedure (reagent) blank (a negative control ) with each sample set. Analyze at least one suitable Cannabis dried plant material, concentrate or oil QC sample (a positive control ) containing at least 50% of the target cannabinoids at concentrations ≥ LOQ. The acceptance ranges for respective analytes in the QC sample must be established based on at least 20 data points collected over multiple days by at least two different analysts. H. Data Processing and Calculations (a) Calculation of Cannabinoid Concentrations. 1. Measure peak area of each analyte in LC-DAD records of calibration standards, QC sample(s), test samples and dilutions. 2. Construct a calibration curve from standards using least squares linear regression analysis by plotting area response versus concentration with 1/x weighting. The calibration curve should not be forced through zero. 3. Determine concentrations of individual cannabinoids in QC sample(s) and test samples. Analyte (%, ⁄ ) = × × × 10,000 where C = analyte concentration determined from the standard calibration curve (µg/mL); V = total volume of the extraction solvent (mL); DF = factor reflecting dilution of the final extract; W = sample weight (g); 10,000 = conversion from µg/g to % ( w/w ). Note: For quantification of cannabinoids, use appropriate extract dilution (if necessary) that yield analyte peak areas within the calibrated range. Perform additional sample extract dilution and re-analyze if required. (b) Identification of Cannabinoids. —Identification of analytes is performed based on comparison of retention time and UV spectra in samples and reference standards. A retention time tolerance of ±0.2 min was used. UV spectra acquired during the elution of each cannabinoid peak in sample and standard are normalized and overlaid. Additional high-confidence identification can be performed using HR MS and MS/MS spectra acquired with Q-TOFMS mass spectrometer. Identification is based on comparison of theoretical and experimental m/z values of either [ M +H] + or [ M –H 2 O+H] + cannabinoid ions and comparison of reference MS/MS spectra with those obtained in samples. A mass tolerance of 5 ppm is employed with a minimum of two fragment ions passing this criterion.

References:

AOAC SMPR 2017.001 Quantitation of Cannabinoids in Cannabis Concentrates J. AOAC Int . 100 , 1200(2017) DOI: 10.5740/jaoacint.SMPR2017.001