Precipitated and separated phosphate radical with bismuth nitrate,CaO and MgO in filtrate are de-terminated by EGTA-EDTA titrimetry,The method is simpler and more accurate than the traditional one.

• 用硝酸铋分离磷酸根离子，在滤液中用EGTA-EDTA分别测定氧化钙，氧化镁较之传统方法简便效果好。