方波溶出伏安法快速测定染发剂中对苯二胺

采用循环伏安法研究了对苯二胺在铂电极上的电化学行为。实验发现,在0.1 mol/LpH=6.0的磷酸盐缓冲溶液中,对苯二胺能在铂盘电极上产生良好的氧化还原峰,对苯二胺氧化还原峰峰电位分别为＋0.25 V和＋0.19 V（vs.Ag/AgC l,饱和KC l溶液）。考察了扫描速度和pH对峰电位和峰电流的影响,结果表明对苯二胺在铂盘电极上的电极反应属于等电子等质子反应,反应过程受吸附控制。基于此建立了方波溶出伏安法快速测定染发剂中对苯二胺的分析方法。该方法具有分析时间短、操作简单等优点。该方法的线性范围为3.24-108.14 mg/L,R=0.9990,检出限为1.1mg/L,浓度为43.2 mg/L时相对标准偏差（n=11）为1.57%,对4种市售染发剂中对苯二胺含量进行了测定,结果满意。

Determination of p-phenylenediamines in Hair Dyes by Square Wave Stripping Voltammeter

The electrochemical behavior of p-phenylenediamine on platinum electrode was investigated by voltammeter. It was found that p-phenylendiamine exhibits a pair of nice reversible redox waves, the cathodic peak （Ⅱ） at ＋ 0.19 V, the anodic peaK（Ⅰ ）at ＋0.25 V （vs. Ag/AgCl, saturation KCl）in 0.1 mol/L PBS. The electrochemical behavior of p-phenylendiamine in different support electrolytes, and different scanning rate was studied. The results showed that the electronic number and the proton number were the same involving in the oxidation of p-phenylendiamine. The electrode reaction of p-phenylendiamine was an adsoption-controlled process. The analyst time was short, easy and so on. The linear range for the determination ofp-Phenylendiamine is 3.24 mg/L- 108.14 mg/L, the regression equation was Ⅰ = 973.35 C ＋ 81.318, and the regression coefficient was 0. 9990. The detection limit was 1.1 mg/L. The electrichemical analysis method ofp-phenylendiamine was set up and determined in hair dyes. The average rate of recovery （ n = 11 ） was 97% -107%, the relative standard deviation （ n = 11 ） was 1.57% for 43.2 mg/L p-phenylendiamine. The developed method has been applied for the determination of p-phenylendiamine in hair dyes with good result.