Abstract: Disclosed is a method for decomposing chondroitin sulfate contained in a sample into disaccharide. In particular disclosed is a method for decomposing chondroitin sulfate contained in a sample into disaccharide by heating the chondroitin sulfate in HCl-methanol containing 2,2-dimethoxypropane at a temperature of 60° C. to 90° C. for 50 minutes to 180 minutes, optionally in the method, the sample is selected from body fluid, a cell, a tissue, an organ, a cell culture solution, a tissue culture solution, a food, and a feed, or a derived therefrom.

Abstract: A method for decomposing dermatan sulfate and heparan sulfate contained in a sample into a disaccharide, respectively, wherein the dermatan sulfate is decomposed into a disaccharide in which a uronic acid and an amino sugar are joined with an ?-1,3 bond, and the heparan sulfate is decomposed into the disaccharide in which the uronic acid and the amino sugar are joined with the ?-1,4 bond, and wherein, the dermatane sulfate is decomposed by heating in hydrogen chloride methanol solution containing 2,2-dimethoxypropane, at a temperature of 60 to 80° C., and for 20 to 100 minutes, and the heparan sulfate is decomposed by heating in hydrogen chloride methanol solution containing 2,2-dimethoxypropane, for 80 to 180 minutes, and at a temperature of 65 to 85° C.