A spectrophotometric method for measuring permanganate index (CODMn) by N,N-diethyl-p-phenylenediamine (DPD)
A spectrophotometric method for measuring permanganate index (CODMn) by N,N-diethyl-p-phenylenediamine (DPD)
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N,N-二乙基对苯二胺（DPD）分光光度法测定高锰酸盐指数（CODMn）
DOI：
10.1016/j.chemosphere.2020.128936
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发表时间：
2021-01-06
期刊：
影响因子：
8.8
通讯作者：
Zou, Jing
中科院分区：
文献类型：
--
作者：
Pang, Zijun;Cai, Yajuan;Zou, Jing
建立了一种测定水中高锰酸盐指数（以高锰酸钾为氧化剂的化学需氧量，CODMn）的新方法。在中性条件下，消解液中残留的KMnO 4能快速氧化N，N-二乙基对苯二胺（DPD）生成稳定的粉红色自由基（DPD中心点+）。只有20秒足以形成粉红色的DPD中心点+。产生的DPD中心点+可以通过可见分光光度计在551 nm处定量测量。KMnO_4与DPD反应的化学计量系数接近1：5（1：5.07）。在0 ~ 4.46 mg L-1范围内，DPD中心点+在551 nm处的吸光度变化与COD_（Mn）浓度呈良好的线性关系（R-2 = 0.999）。DPD法的检出限低至0.02 mg L-1 CODMn。DPD法测定标准溶液中CODMn的准确度高，回收率为99.17%~ 102.22%，且对Cl-和Fe 3+共存的干扰有较好的耐受性。DPD法成功地应用于真实的水样中的CODMn的测定，包括地表水、地下水和饮用水。与传统滴定法相比，DPD法操作简便，所需样品和消解试剂少（即，KMnO_4和H_2SO_4），可用于在线监测。(C)2020爱思唯尔有限公司保留所有权利。
A new spectrophotometric method for measuring permanganate index (chemical oxygen demand using potassium permanganate (KMnO4) as oxidant, CODMn) in water was established. The method was based on the rapid oxidation of N,N-diethyl-p-phenylenediamine (DPD) by residual KMnO4 in digestion solution under neutral pH condition to form the stable pink radical (DPD center dot+). Only 20 s were enough to form the pink DPD center dot+. The generated DPD center dot+ could be quantitatively measured by a visible spectrophotometer at 551 nm. Stoichiometric coefficient of the reaction between KMnO4 and DPD was close to 1:5 (1:5.07). There was a well linear relationship (R-2 = 0.999) between the change of the absorbance of DPD center dot+ at 551 nm and the concentration of CODMn in the range of 0-4.46 mg L-1. Limit of detection of the DPD method was as low as 0.02 mg L-1 CODMn. The DPD method was highly accurate for measuring CODMn in standard solutions with well recovery rates of 99.17%-102.22%, and was well tolerant to the interference of coexistent Cl- and Fe3+. The DPD method was successfully applied for measuring CODMn in real water samples, including surface water, underground water and drinking water. In comparison to the traditional titration method, the proposed DPD method was more convenient to operate, required less samples and digestion reagents (i.e., KMnO4 and H2SO4) and could be employed for online monitor. (C) 2020 Elsevier Ltd. All rights reserved.