聚乙二醇辛基苯基醚增敏光度法测定茶叶中铅的含量  

Determination of Lead in Tea by Polyethylene Glycol Octyl Phenyl Ether Sensitized Spectrophotometry

作　　者：刘立华[1] 邢丹 沈玉龙[1] 杨笑春[1] Liu Lihua;Xing Dan;Shen Yulong;Yang Xiaochun(Department of Chemislry, Tangshan Normal University, Tangshan 063000, China;College of Marine ＆＇ience and Biological Engineering, Qingdao University of Science and Technology, Qingdao 266042, China)

机构地区：[1]唐山师范学院化学系,河北唐山063000 [2]青岛科技大学海洋科学与生物工程学院,山东青岛266042

出　　处：《南开大学学报（自然科学版）》2017年第5期97-102,共6页Acta Scientiarum Naturalium Universitatis Nankaiensis

基　　金：唐山师范学院教改项目(2014001031);河北省高等教育教学改革研究与实践项目(2016GJJG181)

摘　　要：采用聚乙二醇辛基苯基醚增敏光度法测定茶叶中铅的含量.在邻苯二甲酸氢钾-氢氧化钠缓冲溶液中,铅与甲基百里酚蓝反应生成蓝色配合物,非离子表面活性剂聚乙二醇辛基苯基醚的加入大大提高了测定的灵敏度.分别研究了增敏剂用量、显色剂用量、缓冲溶液酸度、显色时间、反应温度对吸光度的影响.结果表明,最佳反应条件为p H=6.2的邻苯二甲酸氢钾-氢氧化钠缓冲溶液2 m L,0.5 g·L-1甲基百里酚蓝溶液4 m L,2 g·L-1的聚乙二醇辛基苯基醚1 m L,室温(25℃)下反应3 min.配合物的最大吸收波长为608 nm.铅(Ⅱ)含量在0-5.6μg·m L-1范围内符合朗伯-比尔定律,标准曲线的线性回归方程为:A=0.034 8 C(μg·m L-1)+0.158 9,相关线性系数为R2=0.999 7,由线性回归方程可得表观摩尔系数为1.8×104L·mol-1·cm-1.测得样品的相对标准偏差(RSD)为2.45%-3.59%(n=3),加标回收率为95.2%(n=3).国标规定茶叶中铅含量不超过5μg·g-1,实验测得茶叶中铅含量为65.28μg·g-1,严重超标.Lead in tea was determined by polyethylene glycol octyl phenyl ether spectrophotometry. In p H=6.2 adjacent benzene dicarboxylic acid potassium hydrogen-sodium hydroxide buffer solution, lead could form a blue complex with methyl thymol blue（MTB）. Non-ionic surface active agent polyethylene glycol octyl phenyl ether was greatly enhanced by the addition of the sensitivity of the assay. The effect of the dosage of the increasing sensitive agent, and the acidity, the developing time and the reaction temperature on determination results were studied. The results showed that the optimum reaction conditions was as follows, p H=6.2 adjacent benzene dicarboxylic acid potassium hydrogen-sodium hydroxide buffer solution（2 m L）, 0.5 g·L-1 methyl thymol blue（4 m L）, 2 g·L-1 polyethylene glycol octyl phenyl ether（1 m L）, at room temperature（25 ℃） reaction for 3 min. The maximum absorption of the complex occurred at 608 nm. Beer＇s law was obeyed in the range of 0-5.6 μg·m L-1 of Pb. The linear equation of the standard curve was A=0.034 8 C（μg·m L-1）＋0.158 9, linear correlation coefficient R2=0.999 7. The apparent molar coefficient was 1.8×104 L·mol-1·cm-1. The relative standard deviation（RSD/%） of the measured samples was 2.45%-3.59%（n=3）, and values of recovery found by standard addition method were in the range of95.2%（n=3）.

关 键 词：铅 聚乙二醇辛基苯基醚 茶叶 分光光度法 湿法消解 

分 类 号：O657.32[理学—分析化学]