An optimized and validated reversed-phase chromatographic method for the simultaneous determination of glucosamine and chondroitin sulphate in dietary supplements

Glucosamine (GlcN) is a natural substance found in chitin, mucoproteins, and mucopolysaccharides. It is involved in the manufacture of glycosaminoglycan, which forms cartilage tissue in the body; GlcN is also present in tendons and ligaments. GlcN must be synthesised by the body, but the ability to do this declines with age. Chondroitin sulphate (CS) is an acid mucopolysaccharide that is a constituent of most cartilaginous tissues. It is used orally as sodium salt in reactive arthrities, such as gonococcal arthritis, and is sometimes given with GlcN for its supposed chondroprotective action in bone, joint, and connective tissue disorders [1]. The developed and validated method based oneself on the quantification of GlcN and galactosamine (GalN), by derivatization with o-phthaldialdehyde (OPA, I) and subsequent reversed-phase chromatographic separation of the obtained adducts (II). GalN was obtained by hydrolysis of the CS complex structure using 7.5 N hydrochloric acid.The RP-HPLC separations were performed at 33±2°C on a Phenomenex Synergi 4mm Fusion-RP 80 A (250 x 3.00 mm i.d.) under isocratic elution conditions using a mobile phase consisting of a mixture of sodium acetate buffer (pH 5.9; 0.05 M) and methanol. The developed method showed good specificity, linearity and repeatability and was applied successfully to quality control of commercial and new manufacturing dietary supplements, without the necessity of preliminary extraction procedures. [1] Sweetman, S. C.; Martindale-The Complete Drug Reference 34th ed., Pharmaceuticals Press, London, 2005: 1670, 1694.