在线紫外光直接活化过硫酸钾消解-磷钼蓝分光光度法测定环境水样中总磷的含量

Online Determination of Total Phosphorus in Environmental Water Samples by Phosphomolybdate Blue Spectrophotometry with Ultraviolet Direct Activated Potassium Persulfate for Digestion

设计并建立了一种在线紫外光直接活化过硫酸钾消解-磷钼蓝分光光度法测定环境水样中总磷含量的系统和方法,并优化验证了系统参数和方法,进行了实际水样的总磷含量测定。水样与过硫酸钾溶液注射混合进入石英螺旋管,紫外光照射活化过硫酸钾消解水样,与抗坏血酸和钼酸铵还原显色后在700 nm处测定吸光度。在石英螺旋管温度为20℃,水样、过硫酸钾、抗坏血酸、钼酸铵流量分别为1.00,0.15,0.06,0.08 mL·min^(-1)的优化条件下,消解率达到97.0%以上,总磷的质量浓度在0.1~5.0 mg·L^(-1)内与吸光度呈线性关系,检出限(3s/k)为0.007 mg·L^(-1)。本方法测定水样的结果与国家标准GB 11893—89进行对比,相对误差为-4.0%~-0.50%。按照标准加入法对湖水样品进行回收试验,回收率为93.0%~100%,测定值的相对标准偏差(n=6)小于3.0%。

A system and method for online determination of total phosphorus in environmental water samples by phosphomolybdate blue spectrophotometry with ultraviolet direct activated potassium persulfate for digestion were designed and developed.The system parameters and method were optimized and verified,then applied to determination of the total phosphorus in the actual water sample.The water sample and potassium persulfate solution were injected into a quartz spiral tube and mixed spontaneously,and the water sample was digested by potassium persulfate which was activated by ultraviolet irradiation.The absorbance was measured at 700 nm after reduction and coloration with ascorbic acid and ammonium molybdate.Under the optimized conditions of quartz spiral tube temperature at 20℃,and the flow rates of water sample,potassium persulfate,ascorbic acid and ammonium molybdate at 1.00,0.15,0.06,0.08 mL·min^(−1),respectively,the digestion rate reached more than 97%.Linear relationship between absorbance and mass concentration of total phosphorus was found in the range of 0.1−5.0 mg·L^(−1),with detection limit(3s/k)of 0.007 mg·L^(−1).The results of water samples determined by this method were compared with those given by the national standard GB 11893—89,and the relative errors ranged from−4.0%to−0.50%.Test for recovery was made on the lake water samples according to the standard addition method,giving results in the range of 93.0%−100%,with RSDs(n=6)of the determined values less than 3.0%.