The Government Chemist has published a review in the Journal of AOAC International on definitive approaches for the authentication of chondroitin, a supplement with a risk of serious adulteration.
What is chondroitin?
Chondroitin is an over-the-counter food supplement of chondroitin sulfate often available in combination with glucosamine sulfate. It is sold widely for a number of uses that range from supplements to medication for animals and humans.
A Cochrane Review of randomized trials found chondroitin (alone or in combination with glucosamine) better than a placebo in improving pain in participants with osteoarthritis in short-term studies. The benefit was small to moderate. More high-quality studies are needed but the combination of some efficacy and low risk may explain its popularity. Singh JA, Noorbaloochi S, MacDonald R, Maxwell LJ. Chondroitin for osteoarthritis. Cochrane Database of Systematic Reviews 2015
Why is it of interest?
The Government Chemist has had a long interest in the analysis of supplements containing chondroitin sulfate stemming from work carried out by a Public Analyst in 2005 that suggested some samples of supplements were deficient of the declared amounts of chondroitin sulfate. However as a natural polymer isolated from parts of either land animals, birds or fish, routine analytical methods for chondroitin tend to be relatively nonspecific and a multi-method approach is required to achieve the goal of affirming identity (including source) and purity. Hildreth, J. and Betz, J.M., 2016. Role of Accurate Methodology in Demonstrating the Safety and Efficacy of Chondroitin Sulfate. Journal of AOAC International
In a review published in January 2018 in the prestigious Journal of AOAC International, Michael Walker and Christopher Mussell of the Laboratory of the Government Chemist and Professor Duncan Thorburn Burns of the Institute for Global Food Security, Queen’s University Belfast make key recommendations for forensically robust analysis for chondroitin sulfate in products. The criteria for the selection of appropriate reference samples of chondroitin sulfate and appropriate orthogonal methods are presented.
For chondroitin to be described as of pharmacopeial standard it must pass all the tests prescribed in the appropriate monograph. As a food supplement, manufacturers may consider pharmacopeial quality to be excessive. Nevertheless, in view of the well-documented cases of serious adulteration of chondroitin-containing products, it is recommended as a minimum to test all raw materials for the currently known/used adulterants and be aware that others may come into the market. In the demonstrated absence of any compromise to the raw material routine quality control analysis is possible by non-specific methods such as titration with cetylpyridinium chloride. However, when required, orthogonal approaches should include a structurally sensitive technique, such as chondroitin-specific enzymatic hydrolysis, followed by HPLC, or mass spectrometry (MS). Nuclear Magnetic resonance (NMR), Infrared (IR), or Raman spectroscopy, coupled with chemometric data evaluation have also been founf useful.
To assist the Official or Referee analyst it is recommended that manufacturers keep and make available upon request samples of the raw material chondroitin sulfate used in each batch to facilitate confirmation of the quality, and, if appropriate, to use as a standard for quantitation.
Burns, D.T., Walker, M.J. and Mussell, C., 2018. Chondroitin Sulfate: A Critical Review of Generic and Specific Problems in Its Characterization and Determination-An Exemplar of a Material with an Unknown or Variable Composition (UVCB). Journal of AOAC International, 101, 196 – 202
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