By Joseph Zhou, Ph.D., Laboratory Director [retired], NOW Foods
Until recently, there was no official test method for analyzing the popular dietary supplement called glucosamine, which comes in various forms such as glucosamine sulfate and glucosamine hydrochloride. This is a common problem for supplement manufacturers and consumers, who want to assure that the highest quality ingredients are used but often lack agreement on exactly how to test each unique material to a common standard. Often, standard methods have not yet been established for identifying and quantifying so many natural substances. And the development of each new testing method can takes years to successfully complete.
A new analytical method developed at the NOW Foods laboratory, Determination of Glucosamine in Raw Materials and Dietary Supplements Containing Glucosamine Sulfate and/or Glucosamine Hydrochloride by HPLC with FMOC-Su Derivatization, has become an AOAC First Action Official Method SM (Reference 1). This method has been designated as AOAC method 2005.01, published in the July/August 2005 issue of the Journal of AOAC INTERNATIONAL (Reference 2). In April 2003, AOAC’s Expert Review Panel (ERP) on glucosamine selected NOW’s glucosamine method as the best method for further laboratory validation. Since then, the method has successfully completed the AOAC’s rigorous validation process, which includes both single laboratory validation (Reference 3) and collaborative study.
As the AOAC study director of the glucosamine method, I organized and led twelve laboratories worldwide for a full collaborative study of the method. Three of these laboratories were industrial dietary supplement finished product manufacturers, five were raw material vendors, three were commercial testing laboratories, and one was a university laboratory. Geographically, ten were in the United States, one in Canada, and one in Germany. Five forms of test materials were included in the collaborative study: (1) tablets, (2) capsules, (3) drink mix powders, (4) raw materials, and (5) liquid products. The materials selected included glucosamine from shellfish as well as vegetable sources, both the hydrochloride and sulfate salts, and glucosamine in combination with other ingredients commonly found to co-occur in dietary supplements - including MSM, SAMe, chondroitin sulfates and vitamin C - at levels commonly found in commercial products. To ensure the reliability of the study, both the identity and ingredients of these test materials were concealed to the collaborators throughout the study, and random identification numbers were used on each of the test materials.
Following AOAC strict rules, the collaborative study was designed and performed to evaluate the accuracy and precision of the method based on its intra- and interlaboratory performance. The study was not easy to manage but was completed successfully, and the study proved that our method is very accurate, specific and reproducible. All twelve collaborating laboratories succeeded in the study. This is worthy of mention since the actual test conditions in different laboratories may vary greatly with various equipment brands, quality, and personnel. None of their reported test results were “outliers” (outside of the anticipated results), indicating the robustness of the method. Based upon the results of the collaborative study, the AOAC Methods Committee on Dietary Supplements voted unanimously to approve this method as an AOAC First Action Official Method SM.
The success of the glucosamine method indicates clearly NOW’s strong commitment to our product quality, also NOW’s high standards and technical strengths in quality testing. The NOW lab has become an internationally recognized leader in assessing the quality of natural dietary supplements.
The 12 Collaborating Laboratories for the Glucosamine Collaborative Study:
Cargill, Inc., Eddyville, IA
Advanced Botanical Consulting & Testing, Inc., Tustin, CA
Covance Laboratories, Inc., Madison, WI
Nature’s Sunshine Products, Inc., Provo, UT
The University of Arizona, Tucson, AZ
Nature’s Way Products, Inc., Springville, UT
Pure World Botanicals, South Hackensack, NJ
Archer Daniels Midland Company, Decatur, IL
Enzymatic Therapy, Inc., Green Bay, WI
JR Laboratories Inc., Burnaby, Canada
BI Nutraceuticals, Long Beach, CA
PhytoLabs, Vesternbergsgreuth, Germany
The AOAC INTERNATIONAL publication, Inside Laboratory Management, July/August 2005, Page 5.
J. Zhou, T. Waszkuc, F. Mohammed, C. Ray, R. Buren, W. Wang, H.Nguyen, J. Jabusch, D. Sullivan, X. Kou, Q. Yang, A. Solyom, J. Wang, T. Peng, Q. Zheng, M. Blumhorst, M. Nagarajan, B. Podhola, L. Huang, C. Shevchuk, R. Das, K. Orellana, K. Reif. Determination of Glucosamine in Raw Materials and Dietary Supplements Containing Glucosamine Sulfate and/or Glucosamine Hydrochloride by High Performance Liquid Chromatography with FMOC-Su Derivatization: Collaborative Study. Journal of AOAC INTERNATIONAL, Vol. 88, No. 4, 2005, Pages 1048-1058.
J. Zhou, T. Waszkuc, F. Mohammed. Single Laboratory Validation of a Method for Determination of Glucosamine in Raw Materials and Dietary Supplements Containing Glucosamine Sulfate and/or Glucosamine Hydrochloride by High Performance Liquid Chromatography with FMOC-Su Derivatization. Journal of AOAC INTERNATIONAL, Vol. 87, No. 5, 2004, Pages 1083-1092.