Dietary Supplements Laboratory Quality Assurance Program

NISTexternal link disclaimer established the Dietary Supplements Laboratory Quality Assurance Program (DSLQAP) in 2007 with support from ODS. The DSLQAP is an extension of collaborative ongoing efforts among ODS, NIST, USDA, and FDA to improve the tools for evaluating dietary supplements.

Program Need: Manufacturers are required to evaluate the identity, purity, quality, strength, and composition of their dietary supplements' ingredients and finished products to be compliant with the Current Good Manufacturing Practices in Manufacturing, Packing, Labeling, or Holding Operations for Dietary Supplementsexternal link disclaimer. One aspect of this evaluation can involve the use of NIST Standard Reference Materials® ( link disclaimer) as controls. Laboratories must also demonstrate analytical proficiency.

Goal: The DSLQAP enables participants to improve the accuracy and precision of their measurements in dietary supplement ingredients and finished products for:

  • nutrients,
  • marker compounds,
  • toxic elements, and/or
  • pesticides.


  • The DSLQAP offers two exercises each year.
  • Three to five samples are analyzed in each exercise.
  • Interested laboratories complete a participation form indicating which samples they are interested in studying. If fewer than eight laboratories sign up for a study, the study will not be conducted.
  • Participants have about two months to complete the analyses once study samples are distributed.
  • NIST chemometricians compile data and provide study participants with feedback regarding the laboratories' performance relative to expected values.
  • NIST distributes to all participants a summary of results in which laboratories are identified by code numbers in order to maintain confidentiality.
  • NIST hosts a workshop following each exercise during which participants discuss results and make recommendations for future exercises.
  • There is no fee for participation and participants are not paid.

Examples of dietary supplement ingredients and contaminants measured in past DSLQAP exercises include:

  • calcium, iron, magnesium, zinc, folic acid, retinol, and alpha-tocopherol in SRM 3280 Multivitamin/Multielement Tablets;
  • fatty acids in SRM 3278 Tocopherols in Edible Oils;
  • lead in SRM 3248 Ginkgo-Containing Tablets;
  • caffeine in SRM 3260 Bitter Orange-Containing Solid Oral Dosage Form;
  • phytosterols in saw palmetto;
  • flavonols in Ginkgo biloba;
  • synephrine in bitter orange;
  • arsenic in ephedra, and
  • vitamins B1 and B2 in SRM 3280 Multivitamin/Multielement Tablets.

DSLQAP Contacts: If you want to participate or are interested in learning more about upcoming exercises, contact the Analytical Chemistry Division within the Chemical Science and Technology Laboratory of NIST: