Modification and application of the method for potentiometric titration of phosphoric acid

The conventional method for potentiometric titration of phosphoric acid was investigated systemically.The titration results using CaCl2 and AgNO3 as precipitants were compared.The recommended modified method using CaCl2 as the precipitant suggested to control the sharp rise of pH value during the second titration at less than 10.3,and to set the third titration end point at a pH value of 7.The results on analysis of phosphoric acid and three different phosphate mixtures showed that the modified method was more accurate and faster than the conventional one.This modified potentiometric titration method will be helpful for identifying optimized synthetic conditions and controlling the performance of phosphate containing products.