【作者】 雷夏；

【导师】 李敬慈；

【作者基本信息】 河北农业大学 ， 分析化学， 2010， 硕士

【摘要】 随着科学技术的发展,在对地质、生物、环境等样品的分析时,经常要求测定痕量金属元素的含量。火焰原子吸收光谱法(FAAS)是金属元素分析中常用的方法之一,但在分析元素含量很低或组成复杂的试样时,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,达到更低的检出限。浊点萃取(Cloud Point Extraction,简称CPE)技术是一种新兴的环保型液-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,将疏水性物质与亲水性物质分离。它不使用挥发性有机溶剂,不影响环境,具有经济、安全、高效、便于实现联用等优点。近年来,浊点萃取技术在生物大分子的分离纯化、有机小分子的分离测定以及金属离子的分离富集等方面得到了广泛的应用。本文研究了以吡咯烷二硫代氨基甲酸铵(APDC)、1(-2-吡啶偶氮)-2-萘酚(PAN)、二乙胺基二硫代甲酸钠(DDTC)为配位剂,Triton X-114为非离子表面活性剂,浊点萃取-火焰原子吸收光谱法测定痕量金属离子的方法。探讨了溶液pH值、试剂浓度、平衡温度等试验条件对三个体系的浊点萃取效率及测定灵敏度的影响,并将此方法用于实际样品的测定。(1)建立了浊点萃取-火焰原子吸收光谱法测定痕量镉的新方法。采用APDC-Triton X-114体系,在最佳条件下,对Cd2+进行浊点萃取,Cd2+的检出限为0.311μg/L,并将此方法用于水样和刺槐中镉的测定,加标回收率为95.3%～102.0%。(2)建立了浊点萃取-火焰原子吸收光谱法测定痕量锌的新方法。采用PAN-Triton X-114体系,在最佳条件下,对Zn2+进行浊点萃取,Zn2+的检出限为0.687μg/L,并将此方法用于水样中锌的测定,加标回收率为95.0%～102.0%。(3)建立了浊点萃取-火焰原子吸收光谱法测定痕量钴、镍和铜的新方法。采用DDTC-Triton X-114体系,在最佳条件下,对Co2+、Ni2+和Cu2+进行浊点萃取,各金属离子的检出限分别为0.288μg/L、0.781μg/L和0.179μg/L,并将此方法用于水样中钴、镍和铜以及刺槐中镍的测定,加标回收率为95.5%～103.2%。更多还原

【Abstract】 With the development of science and technology, analytical methods are required for the determination of trace elements in geological, biological and environmental samples. Flame atomic absorption spectrometry (FAAS) has been widely used for the determination of trace metal ions because of the relatively simple and inexpensive equipment required. However, direct determination of metal ions at trace levels by FAAS is limited not only due to insufficient sensitivity, but also to matrix interference. Under these circumstances, in order to determine trace levels of metal ions, a separation and enrichment step prior to their determinations may be beneficial.Cloud point extraction(CPE) is a new liquid-liquid extraction which is based on the solubility and cloud point phenomenon of aqueous solution of surfactants, upon alteration of the experimental conditions such as pH value 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 metal element.A new method for the determination of trace metal ions by flame atomic absorption spectrometry with cloud point extraction was developed. This method is based on employing Triton X-114 as nonionic surfactant, Ammonium pyrrolidine dithiocarbamate (APDC), 1-(2-pyridylazo)-2-naphthol(PAN) and sodium diethyldithiocarbamate(DDTC) as complexing reagent. The effect of experimental conditions such as pH and concentration of reagents on cloud point extraction was optimized in the following three systems.(1) A new method for the determination of Cd2+ by flame atomic absorption spectrometry with cloud point extraction was developed. In APDC-Triton X-114 system, under the optimum conditions, the detection limit of Cd2+ was 0.311μg/L. The method has been applied to the determination of Cd2+ in samples with satisfactory recoveries ranging from 95.3% to 102.0 %. (2) A new method for the determination of Zn2+ by flame atomic absorption spectrometry with cloud point extraction was developed. In PAN-Triton X-114 system, under the optimum conditions, the detection limit of Zn2+ was 0.687μg/L. The method has been applied to the determination of Zn2+ in samples with satisfactory recoveries ranging from 95.0 % to 102.0 %.(3) A new method for the determination of Co2+, Ni2+ and Cu2+ by flame atomic absorption spectrometry with cloud point extraction was developed. In DDTC- Triton X-114 system, the detection limit of Co2+, Ni2+ and Cu2+ was 0.288μg/L, 0.781μg/L, 0.179μg/L. The method has been applied to the determination of Co2+、Ni2+ and Cu2+ in samples with satisfactory recoveries ranging from 95.5% to 103.2%.更多还原