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Dietary Supplement Testing and Analysis: Quality Control

Dietary Supplement Testing and Analysis: Quality Control

Dietary Supplement Testing and Analysis: Quality Control

Dietary supplements are subject to FDA requirements for good manufacturing practices (cGMP) and quality control in the United States. cGMP require specifications for each ingredient and finished dietary supplement. The specifications list parameters for identity, purity, potency and other requirements for regulatory compliance. Each parameter on the specification must be tested with a scientifically valid method.

NaturPro Scientific, as an UnLab, partners with expert analytical laboratories to conduct specific testing on dietary supplements. Testing typically includes:

  • Physical characteristics (visual, color, odor, taste, density, mesh size)
  • Identity (matching an ingredient in a pass/fail fashion to a particular species of botanical or herb, or a chemical purity test)
  • Potency (concentration of active or marker compounds)
  • Purity (absence of impurities such as moisture, microbiology, pathogens, heavy metals, residual solvents, pesticides, mycotoxins)

The following are analytical principles or instruments that may be used for dietary supplement testing:

  • Karl Fischer
  • Ro-tap and particle size analysis
  • Titration
  • Gravimetry
  • Thin Layer Chromatography (TLC or HP-TLC)
  • High Performance Liquid Chromatography (HPLC)
  • Gas Chromatography with Flame Ionization Detection (GC-FID)
  • Gas Chromatography with Mass Spectrometry (GC-MS of GC-MS-MS)
  • Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
  • Total Aerobic Plate Count
  • Pathogens (Salmonella, E. Coli, Staph)

The following is a list of documentation and regulations requiring testing under cGMPs:

  • Documentation of the specifications established (21 CFR 111.95(b)(1))
  • Documentation of your qualification of a supplier for the purpose of relying on the supplier’s certificate of analysis (21 CFR 111.95(b)(2))
  • Documentation for why meeting in-process specifications, in combination with meeting component specifications, helps ensure that the dietary supplement meets the specifications for identity, purity, strength, and composition; and for limits on those types of contamination that may adulterate or may lead to adulteration of the finished batch of the dietary supplement (21 CFR 111.95(b)(3))
  • Documentation for why the results of appropriate tests or examinations for the product specifications that you selected for testing ensure that the dietary supplement meets all product specifications (21 CFR 111.95(b)(4))
  • Documentation for why any component and in-process testing, examination, or monitoring, and any other information, will ensure that a product specification that is exempted under 21 CFR 111.75(d) is met without verification through periodic testing of the finished batch, including documentation that the selected specifications tested or examined under 21 CFR 111.75 (c)(1) are not able to verify that the production and process control system is producing a dietary supplement that meets the exempted product specification and there is no scientifically valid method for testing or examining such exempted product specification at the finished batch stage (21 CFR 111.95(b)(5))

There are a number of sources of information for developing specifications and test methods for analysis of dietary supplements. The below is a partial list of references and resources:

  1. Dietary Supplement Ingredient Database,
  2. Dietary Supplement Label Database,
  3. Dietary supplement laboratory quality assurance program: the first five exercises. Phillips MM, Rimmer CA, Wood LJ, Lippa KA, Sharpless KE, Duewer DL, Sander LC, Betz JM.  J AOAC Int 2011;94:803-14.
  4. Heavy metals: analysis and limits in herbal dietary supplements,
  5. Pesticide Analytical Manual, Vol I, FDA. Source:
  6. Pesticide Analytical Manual, Vol II, FDA. Source:
  7. Quality assurance of cultivated and gathered medicinal plants. Mathe and Mathe, Source:
  8. Quality control methods for medicinal plant materials (1998) World Health Organization
  9. Recommendations for microbial limits in herbal products, American Herbal Products Association,
  10. Standardization of herbal medicines – A review. Kunle O.F. et al, (2012) Int. J Biodiv and Conserv. 4(3) 101-112. Source:
  11. USP Food Fraud Mitigation Guidance,


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