Analytical Challenges in the Certification of Botanical Dietary Supplement Standard Reference Materials

The National Institute of Standards and Technology (NIST) has been working with the National Institutes of Health Office of Dietary Supplements (NIH/ODS) and the Food and Drug Administration (FDA) Center for Drug Evaluation and Research (CDER) and Center for Food Safety and Applied Nutrition (CFSAN) to produce Standard Reference Materials (SRMs) for dietary supplements. Suites of materials including Ginkgo biloba, saw palmetto, green tea, bitter orange, berries (cranberries, blueberries, and bilberries), black cohosh, and oils containing omega-3-fatty acids are available or in preparation. The SRMs are intended for use as control materials in quality assurance, for method validation, and they are used as control materials in the NIST-ODS dietary supplement quality assurance program. The materials represent a variety of natural, extracted, and processed sample matrices which provide different analytical challenges. Because each botanical material may contain multiple marker compounds, and because two or more independent methods are required for the certification of SRMs, significant effort is required for the value assignment of constituent levels. This presentation will address approaches used in value assignment of dietary supplement SRMs including: extraction methodology, detection specificity and sensitivity, chromatographic method development, and method independence. The use of SRMs for method validation and as control materials will also be discussed.