用萘分光光度法直接测定干茶中的痕量铜

[Direct determination of trace copper in dry tea by spectrophotometry with Naph].

作者信息

Song Yuan-lin

机构信息

Dept. of Chemical Engineering, Xiangtan Polytechnic University, Xiangtan 411201, China.

出版信息

Guang Pu Xue Yu Guang Pu Fen Xi. 2003 Feb;23(1):167-9.

PMID:12939999

Abstract

In the ethanol/water medium containing 0.1 mol.L-1 ammonium acetate (NH4Ac) and 1.5% (w/v) sodium dodecyl sulfate (SDS), the complex chromogenic reaction of trace Cu (II) with 5, 8-dihydroxy-1, 4-naphthoquinone (Naph) has been studied. Based on this study, a novel spectrophotometric method for determining trace Cu (II) has been developed. The results show that the maximum absorption of the colored complex is at 330 nm, the molar absorptivity is 1.8 x 10(4) L.mol-1.cm-1, the detection limit of the method is 0.3 mg.L-1 for Cu (II) and Beer's law is obeyed for Cu (II) in the range of 0.0-4.5 mg.L-1. The linear regress equation of A is 0.290 CCu(II) (mg.L-1) +0.015, the correlation coefficient is 0.9981, the standard recovery of Cu (II) is in the range of 97.9%-104.1% (n = 6) and the relative standard deviation (RSD) is in range of 1.6%-5.1% (n = 6). Both of the precision and accuracy are suitable to microanalysis. The method was applied to trace copper determination in dry tea samples with satisfactory results.

摘要

在含有0.1 mol·L⁻¹乙酸铵（NH₄Ac）和1.5%（w/v）十二烷基硫酸钠（SDS）的乙醇/水介质中，研究了痕量铜（II）与5,8 - 二羟基 - 1,4 - 萘醌（Naph）的络合显色反应。基于此研究，建立了一种测定痕量铜（II）的新型分光光度法。结果表明，有色络合物的最大吸收波长为330 nm，摩尔吸光系数为1.8×10⁴ L·mol⁻¹·cm⁻¹，该方法对铜（II）的检出限为0.3 mg·L⁻¹，在0.0 - 4.5 mg·L⁻¹范围内铜（II）符合比尔定律。吸光度A的线性回归方程为0.290 CCu(II)（mg·L⁻¹） + 0.015，相关系数为0.9981，铜（II）的标准回收率在97.�% - 104.1%范围内（n = 6），相对标准偏差（RSD）在1.6% - 5.1%范围内（n = 6）。精密度和准确度均适用于微量分析。该方法应用于干茶叶样品中痕量铜的测定，结果令人满意。