A Simple and Validated LC Method for the Simultaneous Analysis of Glucosamine and Chondroitin Sulfate Equivalent in Dietary Products

A simple and reliable reversed-phase liquid chromatographic (RP-LC) method was developed and validated to determine simultaneously a glucosamine and chondroitin sulfate equivalent in dietary products. The procedure is based upon the reaction of o-phthaldialdehyde with glucosamine and galactosamine coming from the galactosaminoglycan hydrolysis. The hydrolysis reaction was carried out with hydrochloric acid (7.5 N) at 80°C for 8 hr, whereas, the pre-column derivatization reaction was carried out in alkaline media for 1 min at ambient temperature. The chromatographic separations were performed on a Phenomenex Synergi fusion-RP 80 A (250mm x 3.0 mm i.d.) using a mobile phase consisting of a mixture of sodium acetate buffer (pH 5.9; 0.05 M) and methanol (85:15, v/v). UV-DAD detection at 340 nm was used. Linear responses were observed and the limit of quantitation for both aminosaccharides was about 60 pmol. The intra-day precision (RSD) was about 1.8% and there was no significant difference between intra- and inter-day data. Recovery studies showed good results (99.3–101.0%) with RSD ranging from 1.1 to 2.1%.