Guidelines for Analytical Method Selection & Appropriate Use when Determining Chemical Constituents in Dietary Supplements

Characterization of dietary supplements is a critical factor for assurance of public safety, effectively documenting positive and adverse events, developing and maintaining quality assurance standards, regulatory compliance and, ultimately, for meaningful scientific study. Many modern botanical quality assurance schemes set specifications for select phytochemicals and measure against those specifications as one determinant of quality. While numerous publications describe procedures for determining compounds of interest in plant species, few methods have been systematically evaluated for accuracy, precision, or reliability and often the analysis of finished products is not within the scope of the published method. This approach is further challenged by difficulties related to selection of marker compounds and a lack of reliable reference materials, both botanical and chemical. These particular challenges can be mitigated by taking another approach; the generation of representative chemical profiles or “fingerprinting”. The application of chemometrics to botanical profiles has great potential to create very elegant quality assurance tools. Regardless of the analytical approach adopted, methods must only be employed within their defined scope & applicability. An overview of the concepts “scientifically valid” and “fit for purpose” as well as present case studies from the field of dietary supplement analysis will be presented. Specifically, Vaccinium spp. and Panax spp. will be used as examples to illustrate the multiple challenges involved analytical testing.