Standard reference materials for dietary supplement analysis

Abstract

IntroductionThe National Institute of Standards and Technology (NIST), theNational Institutes of Health Office of Dietary Supplements(NIH-ODS), and the Food and Drug Administration (FDA) areworkingincollaborationtoproducedietarysupplementStandardReference Materials (SRMs). Efforts began following the crea-tion of the NIH Office of Dietary Supplements by the DietarySupplement Health and Education Act (DSHEA) of 1994 [ 1]and the establishment of the NIH-ODS Analytical Methods andReference Materials Program (AMRM) in 2002 [ 2]. AMRM isresponsible for ensuring that quality calibration materials andmatrix-based certified reference materials (CRMs) are availableto dietary supplement laboratories along with rugged, precise,and accurate analytical methods [ 3–7]. More recently, as of June2010, the current Good Manufacturing Practices (cGMPs) pub-lished by the FDA are required for all dietary supplementsproduced in the United States [8] The cGMPs require thatproducts be evaluated for identity, purity, and strength as wellas for contaminants (toxic elements, bacteria, persistentorganic pollutants, and other toxins) and adulterants (eitherunintentional or economically motivated), placing increasedemphasis on the importance of the development of dietarysupplementSRMs.NISTstaffareoftenaskedaboutthestatusof new and existing SRMs; this manuscript is designed toprovide an update on the dietary supplement Standard Refer-ence Materials Program. The Certificates of Analysis foravailable SRMs can be found at nist.gov/SRMs [9] and canbe searched for by keyword or SRM number. The brief de-scriptions of different dietary supplements are all taken fromthe NIH-ODS factsheets [10].Material selectionThere are a number of considerations that factor into theprioritization of materials for the development of dietary sup-plement SRMs. Dietary supplement materials (matrices andtarget analytes) are ranked by an AOAC committee based onthe availability of and need for analytical methods and refer-ence standards. The order of the production of the SRMs isbasedontheneedsoftheNIHandtheFDA,informationfromtheAOACingredientrankingsubgroup(IRS)prioritylist,themarket share, and potential safety considerations associatedwith individual dietary supplements.Botanical dietary supplement SRMs have been developedatNISTassuitesofmaterialsinordertorepresenttherangeofchallenges that may be encountered during analysis.Depending on the product, the suite may consist of a rawbotanical material, an extract, and a finished product (e.g.,ground or whole tablets). Significantly different formulationswith different analytical intricacies may also be added to thesuite. For example, the suite of ephedra-containing materialsconsisted of Ephedra sinica Stapf, Ephedra sinica Stapf Na-tive Extract, Ephedra sinica Stapf Commercial Extract,Ephedra-Containing Solid Oral Dosage Form, and Ephedra-Containing Protein Powder. The plant material presented thegreatest extraction challenges. The extracts and tablets repre-sented the commercially available products with a range of