Studies On The Application For Trace Metal Element Analysis By Coupling Of Cloud Point Extraction To Atomic Spectrometry

Cloud point extraction (CPE) is a new kind of preconcentration and separation technology which has many prominent virtues such as completely phase separation, easily operation, highly enrichment efficiency and kind for environment and operators. Some aspects about CPE and its applications have been studied in this assay as follow:1) The principle, background and significance of CPE were expatiated. The coupling technologies of CPE with atomic spectrometry, molecular spectrophotometry, capillary electrophoresis and chromatography etc., especially their applications in element speciation analysis have been reviewed.2) Atomization behaviors of copper and influences on the spectral background by the diluted surfactant solution introduced into the graphite furnace tube were studied. The novel test method for trace copper by cloud point extraction electro-thermal vaporization atomic absorption spectrometry (ETVAAS) without chemical modifier was proposed. The method was successfully applied in determination of trace copper in drinking water, tap water and sea water and the detect limit was 5 ng/L.3) A new method with cloud point extraction preconcentration-flow injection-inductively coupled plasma atomic emission spectrometry for analysis of cadmium, cobalt, copper, nickel and zinc in water samples was developed. The flow injection system was assembled with a micro injection valve and the instrument equipped peristaltic pump. The CPE concentrated sample was introduced into the ICP with flow injection technique. It not only overcame the difficulties of little amount of sample solution condensed, but can also reduced the influence of organic solvent to plasma discharge. The method was successfully applied to the determination of cadmium, cobalt, copper, nickel and zinc in tap water, river water and sea water. 4) A novel analysis method for the ultra-trace amount methyl-, phenyl- and organic mercury by combination of cloud point extraction to high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was developed. Measures for stabilization of plasma discharge were studied in detail. The introduction of Ar/O₂ mixed optional gas into the plasma ensured stable plasma discharge for a long time running and avoided deposition of carbon particles on the surfaces of the ICP torch, sampling cone and skimmer cone. It was observed that EtHg⁺ was partially decomposed during the process of CPE. The method was successfully applied to the determination of MeHg⁺, PhHg⁺and Hg²⁺ in water and biological samples, and the achieved detection limits were 13, 8 and 6 ng/L for MeHg⁺, PhHg⁺and Hg²⁺, respectively.