浊点萃取火焰原子吸收光谱法测定痕量金属元素的研究.pdf

湘潭大学 硕士学位论文 浊点萃取-火焰原子吸收光谱法测定痕量金属元素的研究 姓名：杨柳 申请学位级别：硕士 专业：分析化学 指导教师：周方钦 20070601 I 摘 要 随着科学技术技术的发展，在进行地质、环境、生物等样品中痕量金属元素 的测定时，常常要求达到 ppb 级的水平，虽然火焰原子吸收分光光度法具有很高 的灵敏度，但是要直接测定这些样品中的痕量组分却很难，这是因为，一方面， 样品本身的物理化学状态有的不适合直接测定，或组分的含量低于分析方法的灵 敏度；另一方面是存在基体干扰因此在分析领域里，往往需要借助分离富集的 手段来提高分析方法的灵敏度和选择性 浊点萃取（Cloud- Point Extraction, CPE）是近年出现的一种新兴的液- 液萃取 技术，它以表面活性剂胶束水溶液的溶解性和浊点现象为基础，通过改变实验参 数，如溶液的pH值、离子强度、温度等引发相分离，从而将疏水性物质与亲水性 物质分离它具有经济、安全、高效、简便，不使用挥发性的有机溶剂，不影响 环境等优点，已广泛用于生命科学、环境科学研究中近年来浊点萃取法也成功 地用于金属元素的分离富集，并与分析仪器联用，用于痕量金属元素的检测。

原子吸收光谱（AAS）检测技术是现今较常用的一种微量元素分析测试手段， 具有仪器价格便宜、精密度高、干扰水平低、线形范围宽等特点将CPE与AAS 联用，可有效的增加分析方法的选择性和灵敏度，降低检出限 本论文以原子光谱分析技术为检测手段，对影响金属离子浊点萃取效率的主 要因素进行系统地研究，并将其应用于实际样品中痕量金属离子的分离富集全 文共分为五章： 第一章：综述了浊点萃取方法的原理和应用，总结前人对浊点萃取研究所取 得的成果和当前国内外的研究现状，并提出了本论文的立题思想 第二章：研究了以 1- （2- 吡啶偶氮）- 2- 萘酚（PAN）为络合剂，以非离子型 表面活性剂 TritonX- 100 为萃取剂的浊点萃取分离富集- 火焰原子吸收光谱法测定 痕量钯的新方法详细考察了溶液的 pH 值、络合剂和表面活性剂浓度、平衡温 度和时间等条件对浊点萃取效果的影响 该方法的线性范围为 0.01～2.00 µg/mL， 检出限为 10.1 ng/mL，相对标准偏差为（RSD）2.12%（n=10） ，回收率在 97.6%～ 105.9%之间用于催化剂中 Pd (II)的测定，结果满意 第三章：研究了以双硫腙为络合剂，以非离子型表面活性剂 TritonX- 100 为 萃取剂的浊点萃取分离富集- 火焰原子吸收光谱法测定痕量金的新方法。

详细考察 了溶液的 pH 值、络合剂和表面活性剂浓度、平衡温度和时间等条件对浊点萃取 效果的影响该方法的线性范围为 0～1.60 µg/mL 检出限为 7.9 ng/mL，相对标准 II 偏差为 4.12%（n=11） ，回收率在 97.5%～102.8%之间，用于矿渣中金的测定，结 果满意 第四章：研究了以对二甲氨基亚苄基罗丹宁（p- DMABR）为络合剂，以非 离子型表面活性剂 TritonX- 114 为萃取剂的浊点萃取分离富集- 火焰原子吸收光谱 法测定痕量银的新方法详细考察了溶液的 pH 值、络合剂和表面活性剂浓度、 平衡温度和时间等条件对浊点萃取效果的影响该方法的线性范围为 0～400 ng/mL 检出限为 1.69 ng/mL，相对标准偏差为 2.95%（n=11） ，回收率在 98.4%～ 103.9%之间，用于水样中痕量银的分离富集和测定，结果满意 第五章：研究了以二乙基二硫代氨基甲酸（DDTC）为络合剂，以非离子型 表面活性剂 TritonX- 100 为萃取剂的浊点萃取分离富集- 火焰原子吸收光谱法测定 痕量铅的新方法，详细考察了溶液的 pH 值、络合剂和表面活性剂浓度、平衡温 度和时间等条件对浊点萃取效果的影响，该方法的线性范围为 0～600 ng/mL 检 出限为 2.41 ng/mL，相对标准偏差为 3.74%（n=11） ，回收率在 97.4%～102.3%之 间，并用于环境水样中铅的测定，结果满意。

关键词：浊点萃取；分离/富集；火焰原子吸收光谱法；痕量元素；钯；金；银； 铅 III ABSTRACT With the development of science and technology, sensitive, rapid, reproducible, simple and accurate analytical methods are required for the determination of trace elements in geological, biological and environmental samples. The direct determination of extremely low concentration of trace element with modern atomic spectroscopic method, such as atomic absorption spectrometry (AAS) is so difficult. On one hand, the limitations are associated not only with the insufficient sensitivity of these techniques but also with matrix interference. That’ s the reason why the separation and preconcentration of trace elements is often required. Cloud point extraction (CPE) is related to the conventional liquid- liquid extraction (LLE). CPE based on the solubility and cloud point phenomenon of aqueous solutions of surfactants, upon alteration of the experimental conditions such as pH value of solution, ionic strength, temperature, and the solution is separated into phases, which results in the separation of hydrophobe and hydrophile. CPE is an easy, safe, high efficiency and inexpensive methodology for separation and preconcentration. It has been widely used in the study of life sciences and environment sciences, and has also been successfully used in the separation and preconcentration of mental element. The atomic absorption spectrometry (AAS), which has the merits of low price and detection limit, good precision and accuracy, and wide linear range, has been widely applied in trace analysis. By coupling CPE with AAS, the analytical performance of the analytical method, such as sensitivity, detection limit and antijamming capability, could be efficiently impoved. The aim of this paper is to systematicaly study on the cloud- point extraction and its application to the separation/preconcentration of metal ions. The major contents are described as follows: Based on the principle and application of cloud point extraction， analysized prevous achievements and current situation in the research of cloud point extraction, and proposed the ideas of this paper. A new method for the determination of trace palladium by flame atomic absorption spectrometry after cloud point extraction was proposed. The effects of experimental conditions such as pH, concentration of chelating agent and surfactant, equilibration temperature and time on cloud point extraction were discussed. Uunder the optimum IV conditions, the detection limit was 10.1 ng/mL, and the relative standard deviation was 2.12% (n=10). The recoveries of Pd2+ ranged from 97.6% to 105.9%. The proposed method has been applied to the determination of palladium in catalyst with satisfactory results. A new method for the determination of trace Gold by flame atomic absorption spectrometry after cloud point extraction was proposed. The effects of experimental conditions such as pH, concentration of chelating agent and surfactant, equilibration temperature and time on cloud point extraction were discussed. Under the optimum conditions, the detection limit was 7.9 ng/mL, and the relative standard deviation was 4.12% (n=11). The recoveries of Au3+ ranged from 97.5% to 102.8%. The proposed method has been applied to the determination of Gold。