DETERMINATION OF ISOTHERMAL-NONISOTHERMAL KINETIC PARAMETERS BY NONLINEAR CURVE FITTING

A continuous nonisothermal-isothermal method for prediction of chemical stability was reported. In this paper, the experimental data were treated by the least square method. Two best approximate curves which shown the relation between temperature and time and between concentration function and time were obtained. All information about chemical kinetics were got from the two curves. The reaction order can be taken in isothermal part and the reaction rate constant, activation energy and frequency factor in nonisothermal part. In order to get the best approximate curves of Arrhenius, the mathematical model was combined with the theory of chemical reaction rate and some points which did not obey the theory were given up by computer. This method was proved by the experiment of hydrolysis of streptomycin sulfate under pH 12 and pH 6.5. By this method the results were approximate to those of isothermal kinetic method, the operation was simple, the experiment was rapid and the result was reliable.