阻抑-褪色光度法测定痕量铅(Ⅱ)  

Determination of Trace Lead (Ⅱ) by Inhibition Discoloring Spectrophotometry

作　　者：刘佳铭[1] 梁卫东[2] 

机构地区：[1]漳州师范学院化学系,福建省漳州市363000 [2]西北师范大学化学系,兰州市730070

出　　处：《光谱实验室》2001年第5期613-617,共5页Chinese Journal of Spectroscopy Laboratory

摘　　要：提出了一种测定痕量铅 ( )新的阻抑 -催化动力学光度法。该法基于溴化十六烷基三甲铵 (CTMAB)对于结晶紫在碱性介质中褪色反应的催化作用和 Pb( )对此催化褪色反应的阻抑效应。在所选定条件下 ,5 90 nm处的表观摩尔吸光系数为 2 .9× 10 7L· mol-1· cm-1,线性测定范围为 0 .0 0 4— 3.2μg/LPb( ) ,检出限为 1.0× 10 -13g/m L。对 1.6μg/L Pb( )测定的 RSD为 3.0 % (n=11)。本阻抑 -催化反应为一级 ,表观活化能为 15 .6k J/mol,速率常数为 8.2 9× 10 -4 s-1。该方法用于水和食品试样中 Pb( )的分析 ,标准加入回收率为 97.9%和 10 3.4 % ,RSD<3.6%。同时 。A new inhibition\|catalysis kinetic spectrophotometry for the determination of trace lead(Ⅱ)was developed.The method is based on the inhibitory effect of lead (Ⅱ) on the catalytic action of cetyl\|trimethylammonium bromide (CTMAB) in discoloration reaction of crystal violet in a basic medium.On the selected conditions,the apparent molar absorption ε 590 is 2.9×10 7L·mol -1 ·cm -1 at 590nm,a linear calibration curve was obtained in the range of 0.004-3.2μg/L Pb(Ⅱ).The detection limit is 1.0×10 -13 g/mL of Pb(Ⅱ).The relative standard deviation for 11 replicated measurements of 1.6μg/L of Pb(Ⅱ) is 3.0%.The inhibition\|catalysis reaction is first\|order,the apparent activation energy is found to be 15.6kJ/mol,and the rate constant is found to be 8.29×10 -4 s -1 .The method has been applied to the analysis of water and food samples,the recovery is 97.9 % and 103.4%,respectively,and RSD is less than 3.6%.The reaction mechanism is also discussed.

关 键 词：阻抑-催化褪色光度法 结晶紫 铅(Ⅱ) 测定 水 食品 CTMAB 痕量分析 

分 类 号：TS207.3[轻工技术与工程—食品科学] R123.1[轻工技术与工程—食品科学与工程]