阻抑动力学光度法测定水中2,4-二甲基苯酚

Inhibitory Kinetic Photometric Determination of 2,4-Dimethylphenol in Water

在磷酸介质中,钌对过氧化氢氧化碱性品红的褪色反应具有强的催化作用,2,4-二甲基苯酚对上述指示反应具有灵敏的阻抑作用,从而提出了一种阻抑动力学光度法测定水中痕量2,4-二甲基苯酚的方法。优化的试验条件如下:①2.0×10-4mol.L-1碱性品红溶液加入量为0.5 mL;②0.1 mol.L-1磷酸溶液加入量为1.2 mL;③过氧化氢(1+99)溶液加入量为0.5 mL;④4.0 mg.L-1钌(Ⅲ)溶液加入量为1.8 mL;⑤反应温度为100℃;⑥反应时间为10 min。2,4-二甲基苯酚的质量浓度在8.0 mg.L-1范围以内与ΔA呈线性关系,检出限(3σ)为3.49×10-4mg.L-1。方法用于环境水样中2,4-二甲基苯酚的测定,测定值的相对标准偏差(n=5)小于6.0%,加标回收率在81.4%～106.3%之间。

It was found that in phosphoric acid medium,the oxidation of fuchsin by hydrogen peroxide was strongly catalyzed by ruthenium（Ⅲ）,leading to an enhancement of color fading of fuchsin.This indicator reaction was inhibited by the presence of 2,4-dimethylphenol.Based on these facts,the determination of traces of 2,4-dimethylphenol in water by inhibitory kinetic photometry was proposed.The optimized conditions found were as follows： ① amount of 2.0×10-4mol·L-1 fuchsin solution： 0.5 mL;② amount of 0.1 mol·L-1 phosphoric acid solution： 1.2 mL;③ amount of hydrogen peroxide solution（1＋99）： 0.5 mL;④ amount of 4.0 mg·L-1 Ru（Ⅲ） solution： 1.8 mL;⑤ temperature of reaction： 100 ℃;⑥ time of reaction： 10 min.Linear relationship between values of ΔA and mass concentration of 2,4-dimethylphenol was obtained in the range within 8.0 mg·L-1.Detection limit（3σ） of the method found was 3.49×10-4mg·L-1.The proposed method was applied to the determination of 2,4-dimethylphenol in environmental water,giving values of recovery ranged from 81.4% to 106.3%,and values of RSD＇s less than 6.0%.