水中磷质量分数的大小标志着水质质量和水处理效果的好坏。对工业循环水中总磷质量分数的测定方法即钼酸铵分光光度法进行了改进，探讨了消解剂、还原剂及其稳定性、硅离子干扰等因素对测定结果的影响，最终确定采用过氧化氢微波消解法。结果表明，该方法消解效果好，消解过程平稳，没有出现浑浊沉淀等现象，且实验准确度高，相对标准偏差在允许的范围之内，回收率为96.8%~99.1%。与其他总磷质量分数测定方法相比，该改进方法操作简便，测定结果可靠，无需掩蔽剂，且不产生酸雾、无污染，安全环保。

The content of phosphorus in water is the sign to evaluate the quality of water and the effect of water treatment.The ammonium molybdate spectrophotometry method,a traditional detection method for mass fraction of total phosphorus in industrial circulating water,is improved.The influences of digestion agent,reducing agent and its stability,silicon ion interference and other factors on the determination results are studied.Finally,the hydrogen peroxide and microwave digestion method is confirmed as the determination method.It is found that through the digestion by hydrogen peroxide,the sample is completely oxidized and the digestion process remains stable.No phenomenon such as turbidity and sedimentation appear during the digestion as that often happens with the traditional method.The reproducibility stays at high level,the relative standard deviation locates within a reasonable range and the recoveries are ranged from 96.8% to 99.1%.Compared with other determination methods for total phosphorus content,this improved method exhibits simple,reliable,no need of masking agent,no generation of acid mist,pollution-free,safety and environmental friendliness.