# Prediction of Isothermal Degradation by the Endpoints Method

Prediction of Isothermal Degradation by the Endpoints Method

Theoretically, when a degradation reaction is known to follow known fixed-order kinetics, its parameters can be determined from two final concentration ratios at two constant temperatures by numerically solving two simultaneous rate equations. Such a solution, however, may require fairly accurate initial guesses that are difficult to assign intuitively. Nevertheless, they can be estimated by manually matching the two experimental points with their corresponding degradation curves using Mathematica’s Manipulate function. Once found, they can be used either as initial guesses or as parameters themselves. This is shown with user-entered endpoints assuming first-order or approximately first-order kinetics and showing how the retrieved parameters can be used to predict the concentration ratio at different temperatures after different times.