电致化学发光法测定Mn^(2+)含量的研究

An Electrochemiluminescence Method for Determination of Manganese (Ⅱ)

在H_3PO_4溶液中,利用Ag^+存在条件下,Mn^(2+)可以被电化学氧化成KMn O_4,KMn O_4进而与酸性邻苯二酚或碱性鲁米诺等发生反应,得到较好的化学发光信号,构建了一种间接测定水溶液中Mn^(2+)含量的方法。研究了Ag^+对Mn^(2+)电化学氧化的影响。Mn^(2+)电化学氧化过程中,当Ag^+浓度为1.5×10^(-5)mol/L,H_3PO_4浓度为0.01 mol/L,电解2 min后,发光强度达到最大。探讨了不同p H条件下的化学发光强度与Mn^(2+)浓度的关系及选择性。在酸性介质中,邻苯二酚的发光强度与Mn^(2+)在1.82×10^(-7)~7.27×10^(-5)mol/L的浓度范围内呈现良好的线性关系;常见的金属离子等对Mn^(2+)测定干扰小。将本方法用于地表水及饮用水中Mn^(2+)的测定,与标准方法相比,结果令人满意。

In the presence of silver ion, Mn2＋ could be electro-oxidized to potassium hypermanganate in phosphoric acid solution, which could effectively react with pyrocatechol in acid solution and luminol in sodium hydroxide solution to produce chemiluminescence. On the basis of this, a novel indirect approach for the detection of Mn2＋ was established. The effect of silver ions on the electrochemical oxidation of Mn2＋ was studied. When 1.5 ×10^-5 mol/L Ag＋ and 0.01 mol/L phosphoric acid solution were used in the process of electrochemical oxidation, the CL intensity could be up to the maximum value after the above solution was electrolyzed for 2 min. The relation of CL intensity and Mn2＋ concentration in the solutions at different pH and the selectivity were also investigated. When the pyrocatechol was used as luminescent reagent in the acidic medium, the CL intensity was linearly to the Mn2＋concentration in the range of 1.82× 10-7-7. 27 × 10-5 mol/L with excellent selectivity. Common ions had little interferences in the determination of Mn2＋. The method was successfully applied to the determination of Mn2＋ in surface water and drinking water with satisfactory results.