AOAC testing method for chondroitin sulfate inches closer to completion

By Clarisse Douaud

- Last updated on GMT

Related tags Chondroitin sulfate Dietary supplements

A single laboratory validation of a method for quantifying
chondroitin sulfate in dietary supplement ingredients has been
completed in California, bringing it one step closer to becoming an
AOAC official testing method for the ingredient.

In 2001, the Association of Analytical Communities (AOAC International) joined forces with the National Institute of Health (NIH), the Office of Dietary Supplements and the US Food & Drug Administration to begin identifying methods for testing dietary supplement ingredients. The aim was to develop 20 AOAC official methods for those dietary supplement ingredients deemed most in need of standard analytical methods, including chondroitin sulfate.

The push to standardize testing methods for specific herbals or compounds used in supplements has risen from a desire to create a level playing ground for the industry in order to enhance its credibility.

Under NIH funding, Analytical Laboratories in Anaheim said it tested chondroitin sulfate - used in supplements primarily for joint health - because quantitative analysis of the compound in raw materials has been challenging due to the wide molecular weight variation of its polymers, poor ultra violet absorbance, and strongly ionic nature.

Dietary supplements containing chondroitin sulfate, which is extracted from animal cartilage like bovine trachea, porcine cartilage, or shark cartilage, are widely available. Together with glucosamine, it is the most commonly used supplement for osteoarthritis.

In the method developed by David Ji, the chondroitin sulfate is first extracted in water, then selectively hydrolyzed by chondroitinase ACII enzyme to form unsaturated disaccharides. The resulting disaccharides are then quantified by ion-pairing HPLC with UV detection and summed to yield the amount of chondroitin sulfate in the material.

A total of six disaccharides are quantified, each differing in either their degree of sulfonation and/or position of sulfonation.

In addition to being able to quantify chondroitin sulfate in raw materials and dietary supplements, the profile of the resulting disaccharides may be used to help identify the source of the chondroitin sulfate.

In the past, methods such as carbazole reaction, cetyl pyridinium chloride titration, and size exclusion chromatography have been used to characterize chrondroitin sulfate, however Analytical Laboratories said these methods are subject to interferences in dietary supplement finished products.

David Ji and Dr. Mark Roman from Tampa Bay Analytical Research are set to co-direct an AOAC collaborative study involving twelve international laboratories on this method. If results from the collaborative study are acceptable, the method will be recommended for adoption as an AOAC official method.

Analytical Laboratories anticipated that the collaborative study will be completed by Spring of 2007.

To date, the ingredients for which methods have been drawn up and validated include ephedra, beta-carotene and glucosamine. The chondroitin, omega-3 and SAMe methods are understood to be amongst those understood to be amongst those nearing completion.

The Council for Responsible Nutrition recently found chondroitin sulfate to have a high level of safety in a risk assessment it recently conducted on this compound and glucosamine.

"The present review provide[s] for a high level of confidence in the safety of these ingredients,"​ said the study authors.

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