流动注射/浊点萃取—光学仪器联用分析生物样品中痕量铬、砷、铅、镉的形态

【作者】 孟杰；

【导师】 任凤莲；

【作者基本信息】 中南大学 ， 分析化学， 2009， 硕士

【摘要】 随着科学技术的发展,在进行地质、生物、环境等样品的分析时,经常要求测定ng/mL甚至pg/mL级的痕量元素,虽然流动注射分光光度法和原子光谱分析等技术具有很高的灵敏度,且在测定样品时所需样品量也不多,但要直接测定这些试样中的痕量组分往往会遇到困难,有时甚至是不可能的,这是因为:一方面,分析方法对极低含量的组分灵敏度不够,或者样品本身的物理化学状态有的不适合直接测定;另一方面是存在基体干扰,或者缺乏相应的校正标准和试剂。因此需要借助于分离富集技术来提高分析方法的灵敏度和选择性。浊点萃取是近年来出现的一种新兴的液-液萃取技术,它不使用挥发性有机溶剂,不影响环境。它以中性表面活性剂胶束水溶液的溶解性和浊点现象为基础,通过改变实验参数引发相分离,将疏水性物质与亲水性物质分离。作为一种分离富集的手段,因其具有萃取效率高、富集因子大、操作简便、安全、经济、便于实现联用化等优点,受到人们的极大关注与重视,并在生物大分子的分离纯化、有机小分子的分离测定及金属离子的分离富集等方面得到广泛的应用。本论文的目的是,以浊点萃取和氢化物发生器作为分离富集手段,以流动注射和可见分光光度计或原子光谱分析技术联用为检测手段,分析痕量铬、砷、铅、镉的形态,并将其应用于实际样品。主要研究内容概括如下:(1)采用浊点萃取作为分离富集手段,采用流动注射-分光光度计做为检测手段,系统地研究了痕量铬不同形态,通过单因素实验和正交试验确定了最佳的萃取条件和实验条件,在优化条件下,分析了生物样品中铬的不同形态,建立了一种铬的形态分析的新方法。(2)采用流动注射-氢化物发生器作为分离富集手段,采用电加热原子吸收法作为检测手段,测定了痕量砷的不同形态,通过控制溶液pH值,即可达到分离(As(Ⅲ))和(As(Ⅴ)),并从理论上解释了原因。在优化的实验条件下,将建立的方法应用于不同水样中的测定,结果满意。(3)采用浊点萃取作为分离富集手段,采用FAAS作为检测手段,对影响金属离子铅、镉的浊点萃取效率的各种因素进行研究,确定最佳的萃取条件和仪器条件,并将其应用于生物样品中不同形态铅、镉的分离和测定。更多还原

【Abstract】 With the development of science and technology, the determination of trace elements often requires more sensitivity. FIA (flow injection spectrophotometry) and AAS (atomic absorption spectrophotometry) have a very High sensitivity and in the process of determination they require a few volume, but if determine the sample directly it will face a lot of difficulties or even impossible. Because on the one hand, the analysis of a very low content of elements lack of high sensitivity or the state of the samples do not suitable for direct determination, on the other hand, there exist matrix interference or lack of appropriate calibration standards and chemical reagent. Therefore, it is necessary to hire the separation and enrichment technology in order to improve the sensitivity and selectivity of the determination.Cloud point extraction (CPE) is a new liquid-liquid extraction technology in recent years with the advantages of little uses volatile organic solvents and do not contaminate the environment. It is based on the solubility and cloud point phenomenon of the neutral surfactant micellar in aqueous solution, the hydrophobic and hydrophilic material will separate by changing the experiment parameters. CPE as a mean of separation and enrichment, it has a lot of merits, such as high extraction efficiency, great enrichment factors, easy to operate, convenient to operate, security, economic and convenient for coupling with other instrument. As a result, it takes people’s great concern and recognition. Now, it has been widely used in the separation and purification of biological macromolecules, the separation and determination of small organic molecules and the separation and enrichment of metal ions and so on.The purpose of this article is to use the cloud point extraction and hydride generator as a means of separation and enrichment, employ FIA coupled with visible spectrophotometer or AAS as the mean of detection to analysis the speciation of trace chromium, arsenic, lead, cadmium and applied to the actual samples. The main contents of this paper can be summarized as follows:(1) Use the cloud point extraction as a mean of separation and enrichment, hire the FIA-VIS spectrophotometer as a mean of detection, systematically studied the speciation of trace chromium. The optimal extraction conditions and experimental conditions were determined through single-factor experiment and orthogonal test. Under the best conditions, the different forms of chromium in biological samples were analyzed.(2) Use the Flow Injection - Hydride Generator as a mean of separation and enrichment, employ the electrical heating atomic absorption spectrometry as a mean of detection, systematically studied the speciation of trace arsenic. As (III) and As (V) could be separated by controlling the pH value of the solution and explained in theory. Under the optimal conditions, the established method was used in different water samples with satisfactory results.(3) Use the cloud point extraction as a mean of separation and enrichment; use FAAS as a mean of detection, systematically studied a variety of factors of the speciation of trace lead and cadmium, determined the optimal extraction conditions and equipment conditions. Furthermore, it was used in the speciation of trace lead and cadmium in biological samples.更多还原