Objective To study the determination of total phosphorus in carbon compound lithium iron phosphate by direct carbon removal gravimetric method. Methods After the sample was decomposed by perchloric acid and the carbon in the sample was removed at the same time, the yellow quinoline phosphomolybdate was precipitated by the reaction of orthophosphoric acid with the precipitant quinomolymonone in the acidic medium. The phosphorus content could be obtained by filtration, washing, drying and weighing. Results The carbon removal by perchloric acid was complete and clear, and the steps of filter and carbon removal were reduced. The precision and accuracy tests of the method were carried out by optimizing the conditions. The relative standard deviation (RSD) of the method was less than 0.2%, and the recovery rate of standard addition was 98.4% ~ 101.1%. The biggest advantage of this method is that carbon is directly removed in the digestion process, eliminating the influence of carbon encapsulation on phosphorus determination, no need to filter carbon removal, shorten the operation process, short analysis time, high content of phosphorus is determined by classical gravimetric method, which has high precision and accuracy, and can provide rapid and accurate results for production. Conclusion This method is suitable for the rapid and accurate determination of total phosphorus in carbon complex lithium iron phosphate.

perchloric acid  /  lithium iron phosphate  /  total phosphorus