磷铁中磷的测定，一般采用王水溶样或碱熔试样。在硝酸介质中，使磷与钼酸铵生成磷钼酸铵黄色沉淀，过滤后用氢氧化钠标准溶液溶解，以酚酞为指示剂，用硝酸标准溶液回滴过量的氢氧化钠。在常压下酸溶解试样时，溶样时间长，酸耗大，样品溶解不完全，使结果偏低；使用碱熔... Phosphorus iron phosphorus determination, the general use of aqua regia sample or alkali fusion test. In nitric acid medium, the phosphorus and ammonium molybdate generated ammonium phosphomolybdate yellow precipitate, filtered with sodium hydroxide standard solution to phenolphthalein as an indicator, with nitric acid standard solution back to the excess sodium hydroxide. Under atmospheric pressure, when the sample is dissolved in acid, the sample has a long time, the acid consumption is large, the sample is not dissolved completely, and the result is low.