The Ins & Outs of Purity Testing

The rising demand for safer, quality dietary supplements, combined with FDA regulatory guidelines, has created new challenges for the manufacturing and production of supplements. As a result, highly accurate purity testing has proven to be a top priority for manufacturers and suppliers that are committed to communicating the efficacy and integrity of their products.

Among the issues that have influenced consumers during the past several years have been the incidents of doping in professional sports, as well as the influx of adulterated foreign products, such as melamine found in products from China. All of this has contributed to a growing scrutiny of the purity of nutraceuticals. To meet these challenges, increasing federal and self-regulation have spurred a new focus on quality stewardship.

FDA regulates dietary supplements as a subset of foods; the Dietary Supplement Health and Education Act (DSHEA) mandated the agency promulgate specific dietary supplement GMPs (good manufacturing practices) to verify quality and uniform production. New GMP requirements went into effect in 2008 for companies with 500 or more employees, with the same regulations being phased in for smaller companies through 2010. Once a dietary supplement goes to market, FDA monitors several safety factors, including product information such as label and packaging claims.

Prior to the release of the federal GMPs, NSF Internationalan independent, not-for-profit organizationdeveloped and wrote an accredited American National Standard for dietary supplementsNSF/ANSI Standard 173. To ensure consistency with the FDA regulations, NSF released a revised NSF/ANSI Standard 173 in June 2008, which includes updated GMPs and testing requirements. Certification of products to this standard provides consumers confidence that what is on the label matches what is in the product. Certification also verifies dietary supplements are produced in accordance with GMPs and do not contain harmful contaminants through purity testing.

Purity Testing

The dietary supplement certification process can be applied to a variety of nutraceutical products, including vitamins, minerals, herbs/botanicals, amino acids, sports nutrition products, concentrates, constituents and extracts. The certification process can be broken down into five steps: application, label and formulation review, facility audit, product testing and listing of product.

As the cornerstone of certification, purity testing helps verify the quality of the product. The label and formulation review during the second step of the certification process verifies the label claims match the formulation of the product. This evaluation also determines the testing required in the fourth step of certification.

Once label and formulations are evaluated, the products are tested to verify identity and quantity as stated on the label of the product, as well as a series of contaminant testing consistent with FDA regulations, which includes:

From the time of harvest, validity of raw material identification and evaluation are established using gross plant morphology and organoleptic testing, which is a method of inspection through visual examination, feeling and smelling of products. A certifier may also determine the validity of qualitative finished product evaluations based on batch records and organoleptic testing. Qualitative evaluation of botanical materials may be performed by such methods as: DNA typing, gross morphology, microscopic morphology, chromatographic fingerprinting (including TLC) or any other appropriate methods. Polymerase Chain Reaction (PCR) has shown promise in qualitative analysis of botanicals. The industry is currently developing PCR capabilities and methods. The form of the ingredient will be used to determine the most appropriate test methodology.

For verification of quantitative claims for specific phytochemicals, vitamins, minerals and other nutrients, analyses performed are specific to the component being measured. Quantitative test methods include: high-performance liquid chromatography (HPLC), gas chromatography (GC), liquid chromatography/mass spectrometry (LC/MS), inductively coupled plasma mass spectrometry (ICPMS) and ICP atomic emission spectroscopy (ICP-AES), as well as several wet chemical methods, including gravimetric and titration techniques. Throughout the testing process, a certifier may use a manufacturer's analytical method(s) while assisting with their validation. In some situations, methods may need to be developed where published methods do not exist for a specific product. NSF collaborates with AOAC International, the National Institutes of Health (NIH), the National Institute of Standards and Technology (NIST) and other organizations to continue the development and validation of compendial standards and test methodologies.

Though methods used for certification may change as additional information becomes available, in such cases, adequate notice will be given prior to the adoption of any new method. Even with an established method in place, preference to an individual manufacturer's method may be appropriate where matrix interferences or other problems warrant.

Kelly Nichols is the communications assistant at NSF International, a not-for-profit, public health and safety organization, and has written on a variety of industry topics for publications, including Beverage Food & World, Natural Products INSIDER and Floor Covering News. She holds a bachelors degree in advertising from Michigan State University in East Lansing.