Abstract: In this paper a study on the model for thermodynamical equilibrium titration has been made. The modeling of the state space and measurement process has been studied. The effects of some parameters,such as the sampling interval,model error,and measurement noise etc.,on the filtering and smoothing estimation have also been examined. Anew method for determining the end-point or equal-point was proposed and satisfactory results were obtained for the simulated and practical titration data.

Key words: Kalman filtering, Titrimetric analysis, Thermodynamical equilibrium titration, Titration model