基于钼酸盐光度法测定总磷的浊度去除方法

采取新的浊度去除方法,改进了测定总磷的钼酸盐光度法。测定过程中,消解液的浊度会对测定结果产生干扰。通过比较机械过滤法和试剂补偿法的浊度校正效果,建立了中速定性滤纸单次机械过滤的浊度去除方法,确定了最佳去除条件:控制待滤液温度不高于30℃,清洗纯水的体积不少于20 m L。选择消解液具有浊度干扰项的6种代表性水样,分别进行平行测定和加标回收试验,方法检出限为0.008 mg/L,测定结果的相对标准偏差为2.8%~7.9%(n=6),加标回收率为92.0%~106%。该方法灵敏度、准确度高,精密度良好,与现行国标法相比,试剂消耗量少,分析效率高,能够满足多种水环境样品中总磷的测定要求。

Turbidity Removal Method of Total Phosphorus Determination Based on Molybdate Photometry

A turbidity removal method for total phosphorus determination was established based on molybdate photometry. The turbidity in the dissolving fluid interfered with the result of the detection. Turbidity correction effect of mechanical filtering method was compared with that of reagent compensation method, and then, a single mechanical filtration turbidity removal of medium-speed qualitative filter method had been established. At the same time, the best removal condition was identified, which included that the filtrate temperature was not more than 30℃ and cleaning water volume was not less than 20 mL. Six kinds of typical selected samples which their dissolving liquid had turbidity interference term were tested for parallel and additive recovery measurements. The detection limit of the method was 0.008 mg/L, the relative standard deviation was 2.8%-7.9%(n=6), and the recoveries ranged from 92.0% to 106%. The method has high sensitivity, accuracy and precision. Compared with the current national standard method, it has advantages including lower reagent consumption and higher analytical efficiency, which can meet the detection requirement of total phosphorus in a variety of samples in the water environment.