Determination of Curcuminoids in Turmeric Dietary Supplements by HPLC-DAD: Multi-laboratory Study Through the NIH-ODS/NIST Quality Assurance Program
Elizabeth Mudge, Paula Brown, Catherine A. Rimmer, Melissa M. Phillips
Background: Turmeric is a medicinal herb containing curcuminoids, which are used as quality markers in dietary supplements. In 2016, a first action official method was adopted for the quantitation of these metabolites and requires multi-laboratory reproducibility data for final action status. Objective: To collect reproducibility data for the quantitation of curcumin, demethoxycurcumin and bis-demethoxycurcumin in dietary supplements through a NIST Quality Assurance Program (QAP). Methods: Laboratories that participated in the QAP following OMA 2016.16 submitted data for ten single- and multi-ingredient turmeric products. The data were analyzed for mean, repeatability and reproducibility standard deviations (SDr/R), repeatability (RSDr) and reproducibility (RSDR). Results: Initial data collection resulted in an insufficient number of replicates (five) for each test sample to determine reproducibility, therefore laboratories were provided with additional test material resulting in an incremental approach for a collaborative study. For homogenous products, reproducibility for curcumin ranged from 3.4 to 10.3 %. Bis- demethoxycurcumin was the least concentrated metabolite with reproducibility ranging from 6.4 to 14.8 %. Demethoxycurcumin had reproducibility ranging from 5.6 to 9.9 %. The method was found to be unsuitable for the quantitation of curcuminoids in complex smoothie products, products containing microbeads or tinctures based on the large variances between laboratories. Several recommendations were suggested for future multi-laboratory studies performed through quality assurance programs and using incremental approaches. Conclusions: OMA 2016.12 is suitable for the quantitation of individual curcuminoids and should be adopted as a final action official method for single and multi-ingredient dietary supplements containing dried roots, dried powders/extracts in bulk material, capsules and softgels.
, Brown, P.
, Rimmer, C.
and Phillips, M.
Determination of Curcuminoids in Turmeric Dietary Supplements by HPLC-DAD: Multi-laboratory Study Through the NIH-ODS/NIST Quality Assurance Program, Journal of Aoac International, [online], https://doi.org/10.1093
(Accessed April 19, 2021)