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Sodium hexametaphosphate is commonly used as a detergent or as a water-treatment additive.
* Updated 8/5/14
Sodium hexametaphosphate, commonly used as a detergent or as a water-treatment additive and sold under the commercial name Calgon, is being used to adulterate chondroitin, a leading joint-health ingredient, says a research group.
Sodium hexametaphosphate is a polyphosphate salt. Aishan Li, director of R&D and quality control of Meitek Technology, a subsidiary of chondroitin sulfate supplier Synutra Ingredients (Rockville, MD), first reported its presence in chondroitin in 2013. Since then, a research group comprising several companies-Synutra Ingredients, Flora Research Laboratories, the United States Pharmacopeia, and Tampa Bay Analytical Research Laboratories-have worked to identify the adulterant, which some dub Zero One (Z1), and to determine the best method of testing for it.
“It is an industrial chemical that is inexpensive and easily available,” says James Neal-Kababick, director of Flora Research Laboratories.
Sodium hexametaphosphate is not necessarily harmful to humans when ingested in small amounts, “but if the level of adulteration goes to about 10% of the supplement serving size, it depletes calcium from the body,” says Jana Hildreth, director of technology and scientific affairs at Synutra Pure.
The most commonly used chondroitin assay method, cetylpyridinium chloride (CPC) titration, may not be sufficient to test for Z1, the team says. Synutra recommends using CPC only after cellulose acetate membrane electrophoresis (CAME), or other assay methods such as enzymatic HPLC, are used. CAME is considered a complementary test to CPC, but currently few chondroitin suppliers may use it.
“Of the known chondroitin adulterants identified to date, including sodium alginate, propylene glycol alginate sulfate sodium, and sodium hexametaphosphate, all can be separated out from chondroitin material by their difference in electrophoretic mobility,” says Weiguo Zhang, president of Synutra International. He is recommending that chondroitin suppliers adopt widespread CAME testing, calling the procedure “inexpensive, simple, and effective.”
Annual global chondroitin sales are currently about $1 billion, the group says. Most chondroitin ingredients sourced from overseas, making the ingredient especially susceptible to economically motivated adulteration.
The research team investigating Z1 plans to publish its findings in a peer-reviewed journal in the near future.
The research group has not gone so far as to test finished products on the market for Z1 presence. "Due to limited access to proprietary sampling practices, the Synutra team is in no position to gauge the prevalence of Z1 adulteration in the supply chain. We are, however, submitting the research data through a peer-reviewed journal publication, which, hopefully, will become available to the public, the scientific community, and the industry," Zhang tells Nutritional Outlook.
"We are also working with industry groups and regulators to promote the use of the CAME method that does effectively detect the presence of Z1 in chondroitin ingredients," he says. "CAME is an easy and inexpensive method that can be set up quickly. If you are not prepared to have your own setup in the lab, you could try a third-party lab that does offer the test. One lab I know who offers this is Flora Research Laboratories."
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