NPIcenter.com : Industry Blogs - Chondroitin Testing Methods

Location: Blogs Analysis and Product Quality
Posted by: jhildreth	1/21/2007 1:58 PM
The recent press release, "Single Lab Validation for Chondroitin Sulfate Completed" , has generated a lot of buzz in the dietary supplement community. Numerous questions regarding the method are being posed and it seems a forum for discussion is needed. To begin let us address the most frequently asked question, "Why did AOAC go with a different method from USP?" The USP publishes monographs, which are collection of methods (see http://www.usp.org/USPNF/), not just a single analytical method. The individual methods in the USP monographs are not intended to be used as "stand alone" methods and thus, individually are not suitable for determining the quality or purity of chondroitin. Unfortunately it is a common practice in the Dietary Supplement Industry, to employ the CPC analytical method while claiming to follow the USP. The problem with using only the CPC method is that it is "non-specific" and as such is not suitable for testing chondroitin levels in finished products containing other ingredients which can interfere with the test results. The current AOAC method was selected for its specificity to chondroitin and is suitable for use in assessing the quality of chondroitin as a single entity and within a product formulation.

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Comments (3)

Re: Chondroitin Testing Methods

By njacobs on 1/23/2007 10:26 PM

I am so glad to hear from someone who seems to understand the ins & outs of the analytical issues our industry faces. AOAC is developing new methods for so many dietary ingredients and that is a good thing. But the fact remains that the AOAC already has dozens of good test methods for dietary ingredients and the new ones will not be preferred over the existing ones. They'll just be new. I hope there is some way that you can use your forum and expertise to help people understand what these analystical issues are all about. Some of the bad press reports would read entirely differently if we could all agree to using compendial methods that are suited to our materials and their matrices.
Keep talking, Jana! I'm encouraging everyone I know to start watching for your comments.

Re: Chondroitin Testing Methods

By jamesnealk on 1/24/2007 11:11 PM

Thank you Jana for some intellegent comments on this issue. For years, we have been using enzymatic HPLC methods for chondroitin in FDP's becuase CPC is simply not suitable for tablets and other finished dosage forms. CPC is easily fooled by carageenan and other compounds as well. It was never intended to be a QC method for FDP's and to stand alone. Like you said, the test is one in a suite of tests to be done as a group. I encounter this issue all the time in the lab. One test does not make a total product quality determination. It is the process of combining several tests that allow a good chemist to draw conclusions abou the product quality. I am eager to try out the new AOAC method and I know the developers of this assay. This is going to be a big help to industry.

Re: Chondroitin Testing Methods

By mroman123 on 1/25/2007 11:28 AM

There have been a lot of questions about the proposed AOAC method for chondroitin sulfate and how it works. Chondroitin sulfate is a polymer. It is made up of repeating units of alternating amino sugars and glucuronic acid. These repeating “disaccharide” units can also have varying degress of sulfonation – hence the name “chondroitin sulfate.” Because it is a polymer with a wide molecular weight range, it is not a single compound, and so quantitation of chondroitin sulfate in raw materials and dietary supplements is difficult.

Luckily, nature has provided us with a tool to help in the analysis of chondroitin sulfate. A group of enzymes known as “chondroitinase” enzymes will break down the polymer into its building block disaccharides. A particular enzyme, chondroitinase AC, is specific for chondroitin sulfate and will not break down any of the related polymers (called glycosamino glycans, or GAGs) found in nature, such as dermatan sulfate, heparin, heparan sulfate, keratan sulfate, and hyaluronic acid. There are only a limited number of these disaccharides that are formed from chondroitin sulfate, and they can be quantified by HPLC. By adding up the total amount of disaccharides formed from the chondroitin sulfate when it is treated with chondroitinase AC enzyme, we can know the total amount of chondroitin sulfate present, whether it is in a raw material or a finished product. Unlike some other analytical methods that are used to quantify chondroitin sulfate, such as CPC titration and carbazole reaction, the results of this method are not affected by the presence of other GAGs.