Determination of bioactive nonvolatile ginger constituents in dietary supplements by a rapid and economic HPLC method: Analytical method development and single-laboratory validation

Most of the validated methods for ginger-containing dietary supplements have long run time and low sensitivity and only analyze gingerols and shogaols. 6-Paradol and zingerone become popular in modern dietary supplement industry as bioactive ginger constituents. Therefore, we developed an efficient HPLC-UV/Vis method to analyze all above major constituents. Compared to 282/280 nm used by the current compendial United States Pharmacopeia (USP) monograph method and International Organization for Standardization (ISO) 13685-1997 method, detection wavelength was optimized to 230 nm which showed a higher sensitivity (signal-to-noise ratio) and better peak resolution. For measuring the ginger constituents in AOAC required matrices, the method was demonstrated to be selective, linear (R² > 0.999), specific, accurate (91.1-103.2% spike recovery rate) and precise (RSD_r < 5%, RSD_R < 8%). Among 10 commercial ginger-containing samples that we screened using this method, the results were 80-123% of the products' labeling value. The HPLC running time was successfully shortened from 29 min (USP method) and 40 min (ISO method) to 12 min without the need of using an expensive Mass Spectrometer for analyte separation. The method is the first method that meets all AOAC SMPR 2017.12 requirements and therefore has the potential to be adopted as a consensus industrial reference method for meeting FDA's cGMP Compliance for the manufacture and quality control of dietary supplements and ingredients.