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
Rapid Determination of Chemical Oxygen Demand in Environmental Water Samples by Merging Zone Stop-Flow Injection Spectrophotometry
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摘要: 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.Abstract: A method is proposed for the determination of chemical oxygen demand (COD) in environmental water samples with merging zone stopflow injection spectrophotometry in KMnO4 system. The determination condition was optimized with temperature of 70℃, pump speed of 1.5 mL/min, stopflow 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 10 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/Lwith dynamic linear range of 3~150 mg/L for COD. The precision of the method is 12%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
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