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测定磷肥中的全磷量:以前采用焦磷酸镁重量法和磷钼酸铵容量法,要经过沉淀,过滤,灼烧沉淀等步骤,手续繁琐,费时较多。现采用EDTA钠盐络合滴定法、在测定样品中加定量的氯化镁和氨水,使之生成磷酸铵镁沉淀,过滤,吸部分清液,控制pH值为10,加铬黑T指示剂,用0.1M EDTA钠盐溶液滴定,仅用1小时左右就能完成。
Determining the amount of total phosphorus in phosphate fertilizer: Magnesium pyrophosphate gravimetric method and ammonium phosphomolybdate volumetric method were used in the past to pass the steps of sedimentation, filtration, burning and sedimentation, and the procedures were complicated and time-consuming. Is the use of sodium EDTA complexation titration method, the determination of the sample was added quantitative magnesium chloride and ammonia, so that the formation of magnesium ammonium phosphate precipitation, filtration, suction part of the supernatant, the control pH value of 10, plus chrome black T indicator Titration of 0.1M EDTA sodium salt solution can be completed in only about 1 hour.