THERMAL DESTRUCTION OF CHONDROITIN SULPHATE ISOLATED FROM BARENTS SEA HYDROBIONTS

Abstract

The results of the thermogravimetric analysis of chondroitin sulfate, isolated from the cartilage of salmon, the northern slope, and the blackmouth shark in the temperature range of 40-600 °С are shown. Thermal analysis was performed using differential thermogravimetry and differential scanning calorimetry. The crystallinity degree of the samples was evaluated using diffraction patterns. It was shown, that under experimental conditions, thermal decomposition of the bulk of chondroitin sulfate samples is observed at a temperature of 230 to 530 °C. Differential thermogravimetric curves and differential scanning calorimetry curves contain five endothermic peaks associated with desorption of physically present water. Desorption of bound water occurs almost to a temperature of 150–200 °C, which can be explained by the difficulty of breaking hydrogen bonds between water molecules and polar functional groups of chondroitin sulfate. Small endothermic peaks correspond to the process of removal the physical volume of water. Four consecutive exothermic peaks are associated with the thermal destruction of the acid, pyranose, and finally, residual carbon and sulfur compounds. The rates of mass loss at each site were determined and the activation energies of each event were calculated. The nature of the cartilage tissue from which chondroitin sulfate is extracted affects the rate of destruction. So, in the temperature range of 236-244 °С, the lowest rate of destruction is observed for XC samples isolated from salmon cartilage tissue. The effect of crystallinity degree on the process of thermal destruction of chondroitin sulfate samples is shown. The results of the thermal destruction of chitin / chitosan obtained from the northern shrimp are presented. It was found that less activation energy is required for thermal destruction of chondroitin sulfate compared to chitin/chitosan at all stages.