采用流动注射光度法测定了水中总磷量。水样经硫酸和过硫酸钾在125 ℃消解后,所得样品溶液中磷(PO43-)与钼酸铵生成杂多酸,经还原成钼蓝后测定其吸光度。总磷的质量浓度在1.0 mg·L-1以内与其吸光度呈线性关系,方法的检出限(3S/N)为0.003 mg·L-1,测定下限(10S/N)为0.012 mg·L-1。方法用于测定水样中总磷的含量,相对标准偏差(n=7)在1.5%~3.0%之间,加标回收率在95.7%~102.5%之间。

A flow-injection analyzer was used for the determination of total phosphorus in water. The water sample was digested with H2SO4 and potassium persulfate at 125 ℃. Phosphosrus, present as ortho phosphate in the sample solution was reacted with ammonium molybdate to form heteropoly acid the absorbance of which after reduced by ascorbic acid was measured photometrically. Linear relationship between values of absorbance and mass concentration of total phosphorus was obtained in the range within 1.0 mg·L-1, with values of detection limit (3S/N) of 0.003 mg·L-1 and lower limit of determination (10S/N) of 0.012 mg·L-1. The proposed method was applied to the determination of total phosphorus in water samples, values of recovery found by standard addition method were in the range of 95.7%-102.5% with RSD′s (n=7) in the range of 1.5%-3.0%.