| Nowadays, it is required for the determination of ultratrace metals in environmentaland geological samples when analyzing methods. Graphite furnace atomic absorptionspectrometry （GFAAS） is one of widely used techniques for determination of tracemetals. With the development of analytical chemistry, direct analysis trace metals indifferent samples becomes a difficult and even impossible task due to matrix interference,but also to insufficient sensitivity. Therefore, it is necessary that some kinds of separationand preconcentration procedures must be involved prior to trace metals determination,which separate analyte and sample matrix and concentrates the analyte for bettersensitivity, selectivity and lower detection limits.In recent years cloud point extraction （CPE） is an attractive area for the separationand preconcentration of trace metals. The method is based on the property of non-ionicsurfactants in aqueous solutions to form micelles and cloud point phenomenon ofaqueous solution of surfactants, upon alteration of the experimental conditions, themicellar solution separates in a surfactant rich phase of a small volume and in a diluteaqueous phase. Its major advantages are simple experimental procedure, highpreconcentration factors, and environmental safety. It has been used for the extractionand preconcentration of organic compounds and metal ions after the formation ofsparingly water soluble complexes.The aim of this dissertation is to combine cloud point extraction with GFAASdetection, employing Triton X-114as nonionic surfactant,2-（5-bromo-2-pyridylazo）-5-dimethylamino-amino-benzen （5-Br-PADMA） and2-（5-iodine-2-pyridylazo）-5-dimethylamino-amino-benzen （5-I-PADMA） as complexing reagent, symmetrically optimize the experimental factors affecting CPE including pH, amount of Triton X-114,volume of5-Br-PADMA and extraction temperature and time and its application to theseparation and preconcentration trace metals in different water samples. The majorcontents are described as follows:（1） A new method for the determination of Co2+by graphite furnace atomicabsorption spectrometry with cloud point extraction was developed. In5-Br-PADMA-Triton X-114system, the concentration of chelating agent and surfactant, pH wereoptimized. the calibration curve was linear in the range of0.05～1.0ng/mL and thedetection limit was4.2ng/L. The method has been applied to determination of cobalt inwater with satisfactory results.（2） CPE in combination with GFAAS has been developed for the preconcentrationand determination of palladium. Palladium was complexed with5-Br-PADMA as acomplexing agent and concentrated by Triton X-114as a surfactant. the calibration curvewas linear in the range of0.1～10.0ng/mL and the detection limit was0.068ng/mL withthe enhancement factor of45.（3） A new method for the determination of Rh3+by GFAAS with cloud pointextraction was developed. In5-Br-PADMA-Triton X-114system, the concentration ofchelating agent and surfactant, pH were optimized. the calibration curve was linear in therange of0.1～3.0ng/mL and the detection limit was0.024ng/mL with the enhancementfactor of26.（4） A new cloud point extraction （CPE） separation of trace level of copper as a priorstep to its determination by GFAAS has been developed. The CPE method was based onemploying Triton X-114as surfactant and5-Br-PADMA as complexing reagent. Thechemical variables affecting CPE were evaluated. Under the optimum conditions, thelinear ranger is0.05-4.0ng mL-1, the limit of detection of0.017ng·mL-1for copper. Theproposed method was applied to the determination of copper in water samples withsatisfactory result.（5） A new method for determination of trace nickel by GFAAS after CPE was developed. The cloud point extraction system was based on Triton X-114as surfactantand5-Br-PADMA as complexing reagent. The parameters affecting cloud pointextraction including pH, amount of Triton X-114, volume of5-Br-PADMA and SDSextraction temperature and time were optimized. The detection limit was0.031ng/mL,the linear in the range of0.1-5.50ng/mL with the enhancement factor of31.（6） Cloud point extraction employing the5-Br-PADMA as complexing agent andTriton X-114as the nonionic surfactant is proposed for cobalt determination. Thechemical variables affecting the sensitivity and the extraction efficiency, such as pH,concentration of5-I-PADMA and Triton X-114, equilibration temperature and time, wereoptimized. Using the optimum conditions, the method allowed cobalt determination witha detection limit of0.011ng/mL, and the analytical curve was linear in the range of0.1-2.0ng·mL-1.The calculated precondition factor was20obtained for a10mL waterexample. The method was successfully applied to the determination of trace cobalt inwater samples.（7） Cloud point extraction employing Triton X-114as the nonionic surfactant,5-I-PADMA as complexing agent and nitric acid-methanol as viscosity regulator isproposed for Rh3+determination by GFAAS. Using the optimum conditions, the methodallowed cobalt determination with a detection limit of0.023ng/mL, and the analyticalcurve was linear in the range of0.1-6.0ng·mL-1. |
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