Detector Response, Curve Fitting, and “Potency Inflation”

Understanding the impact and significance of different calibration curve schemes as they relate to the quantification of analytes is imperative in the laboratory. The consensus throughout the cannabis industry is that the quality of calibration curves, which are linear, should be measured based on the R2 value. However, while this may be a good general principle to follow, it can prove to be problematic when analytes are being measured just beyond their dynamic linear range.

The Cannabis Working Group (CWG) of the American Council of Independent Laboratories (ACIL) undertook a collaborative volunteer research study, which aimed to determine the variability amongst cannabinoid certified reference materials (CRMs) used by cannabis laboratories for creating calibrations. While the overarching goal of the study was to determine the variance of THC and THCA, other interesting conclusions were also drawn from this collaborative study, including a better understanding of detector response and curve fitting, and the impact this may have on “potency inflation”.
This presentation will focus on displaying the impact that different calibration schemes and curve fits can have on the quantification of cannabinoids by comparing various CRMs. Additionally, the relevance to stakeholders will be presented through the quantification of real-life samples against both quadratic and linear curve fits for analytes that fall within and outside the linear dynamic range. Finally, the presentation will provide suggestions for laboratories on how to read between the lines when evaluating calibration curves to ensure that the parameters being followed are not negatively impacting the accuracy of the analytes being quantified.