流动注射合并带停留光度法快速测定环境水样中化学需氧量

研究了KMnO4体系流动注射合并带停留分光光度法对环境水样中化学需氧量(COD)测定的试验条件,包括反应试剂KMnO4的浓度、载流H2SO4的酸度、采样泵泵速及停留时间、反应温度、试剂体积和采样环体积。在不加HgSO4的条件下,Cl-的质量浓度达10000 mg/L对测定无干扰。方法的线性范围为3~150 mg/L,检出限为1 mg/L,精密度(RSD,n=7)为1.2%。方法具有仪器简单,操作方便、快速,干扰少,灵敏度高等优点,用于河水、池塘水和地表水等实际样品的分析,测定值与经典重铬酸钾标准方法结果基本一致。

Rapid Determination of Chemical Oxygen Demand in Environmental Water Samples by Merging Zone Stop-Flow Injection Spectrophotometry

A method is proposed for the determination of chemical oxygen demand(COD) in environmental water samples with merging zone stop-flow injection spectrophotometry in KMnO4 system.The determination condition was optimized with temperature of 70℃,pump speed of 1.5 mL/min,stop-flow time of 60 s,sampling volume of 300 μL,reagent volume of 150 μL,KMnO4 concentration and acidity of 0.08 mol/L and 1.0 mol/L respectively,the acidity of the carrying liquid(H2SO4) of 1.0 mol/L and analytical frequency of 30 samples per hour.Up to 10000 mg/L of Cl– does not interfere on the determination.The detection limit of the method is 1 mg/L with dynamic linear range of 3~150 mg/L for COD.The precision of the method is 1.2%RSD(n=7) for the sample with 50 mg/L of COD.The method has been applied to the determination of COD in river,pool and surface water samples and the results are in agreement with those obtained by traditional potassium dichromate method.