Rapid Determination of Polymerized Phosphorus in Calcium Magnesium Polyphosphate Fertilizer
WANG Botong;HU Zhaoping;YU Nanshu;Kingenta Ecdogical Engineering Group Co., Ltd.;National Engineering & Technology Research Center for Slow and Controlled Release Fertilizers;State Key Laboratory of Nutrition Resources Integrated Utilization;
A method for indirect and rapid determination of polymerized phosphorus in calcium magnesium polyphosphate fertilizer is proposed. EDTA disodium salt solution is used to extract the polymerized phosphorus in calcium magnesium polyphosphate fertilizer, and the pH of the sample solution is adjusted to 12.0 to 12.5 with 5 mol/L sodium hydroxide solution, and the sample is dissolved by boiling for 15 minutes. The quinoline phosphomolybdate gravimetric method is used to determine the content of available phosphorus, and the phosphorus vanadium molybdata yellow colorimetric method is used to determine the content of orthophosphate. The difference between the content of available phosphorus and orthophosphate is the content of polymerized phosphorus. The test results show that the recoveries of samples at 4 concentration levels range from 98.43% to 104.40%, and the relative standard deviation is less than 4%. This method has the characteristics of high accuracy and good reproducibility.