石墨炉原子吸收法测定植株镉消除背景值的改进方法

doi:10.3964/j.issn.1000-0593(2009)09-2577-04

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摘要：利用传统高温干法灰化植株样品和石墨炉测定镉，存在峰高计算法背景值高、测定结果偏低的问题，这对评估那些镉含量处于临界值附近的样品，带来很大困难。为了解决这一问题，文章针对石墨炉测定镉的背景值，对传统方法的前处理实验过程进行了部分改进，并对基体改进剂的适宜浓度进行了比较筛选。结果表明, 在样品灰化前加入基体改进剂硝酸镁，不仅不会使灰化液产生沉淀，而且可使背景吸光值降低一个数量级，可大大减少干扰。另外，用浓度为3%的稀硝酸代替1 mol·L^-1HCl作灰化液基体可以基本消除背景值。改进方法的空白值接近0浓度，从而使测定值重新得到校正，结果更加准确。

关键词：石墨炉原子吸收;镉;背景

Abstract：A problem of higher background value and lower measured Cd value exists when Cd is digested by conventional dry digestion method, measured by graphite furnace atomic absorption, and calculated with peak height numeration. This problem results in difficulty for evaluating samples with Cd contents in the neighborhood of critical values. In order to solve the problem, the present paper focused on background measurement with graphite furnace atomic absorption, modified the pre-preparation procedures of the traditional method, and screened the optimal concentration of the modifier. Results showed that addition of Mg(NO₃)₂ as a modifier into the samples before incineration was preferred. It could not only yield a clear solution but also reduce its background by ten times, considerably eliminating background interference. In addition, using 3% HNO₃ in stead of 1 mol·L^-1 HCl as dilution for the incinerated sample could eliminate the background. The improved methods could acquire a zero concentration of measurement for the blank, re-correct the values measured by graphite furnace atomic absorption and obtain more reliable results.

Key words：Graphite furnace atomic absorption;Cd;Background

收稿日期: 2008-08-20 修订日期: 2008-11-18

中图分类号:

S132

通讯作者: 涂仕华 E-mail: stu@ipni.net

引用本文:

喻华,冯文强,秦鱼生,陈庆瑞,曾祥忠,涂仕华^* . 石墨炉原子吸收法测定植株镉消除背景值的改进方法[J]. 光谱学与光谱分析, 2009, 29(09): 2577-2580.
YU Hua, FENG Wen-qiang, QIN Yu-sheng, CHEN Qing-rui, ZENG Xiang-zhong, TU Shi-hua^*. Methodology Improvement in Background Elimination in Plant Cd Measurement by Graphite Furnace Atom Absorption. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2009, 29(09): 2577-2580.

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