Evaluation of the measurement uncertainty for the determination of phosphoric acid contents in food additive-phosphoric acid by gravimetric analysis

According to JJF1059-1999Evaluation and Expression of Uncertainty in Measurement,A mathematic model for the determination of phosphoric acid contents in food additive-phosphoric acid by gravimetric analysis was established.The calculation formula was deduced.Some data were collected in the procedure of analyzing the sample and the uncertainties of various variables were calculated.The combined uncertainty and expanded uncertainty were finally obtained by synthesizing the uncertainties of various component variables.Results of determination and evaluation of the measurement uncertainty were(85.66 0.24)%,k=2.The major source of uncertainty was the loss of precipitate by washing.