Modification Of Magnetic Nano-materials And The Application In Chromium Speciation

Solid phase extraction (SPE) has become one of the most important techniques used for separation and preconcentration due to its advantages of low organic solvents consumption, rapid phase separation, strong stability, good selectivity, high enrichment factor, high adsorption capacity, closed operation without introducting pollutants, simple preparation method, easy automation, good ability of combination with different determination techniques etc.. The aim of this dissertation is to develop new solid phase extraction materials and new magnetic solid phase extraction technology, to establish new technology of combination flame atomic absorption spectrophotometer (FAAS) with magnetic solid phase extraction (MSPE) and new method of chromium species analysis. The main contents are as follows:(1) A method has been developed for the determination of trace chromium species (Cr(III) and Cr(VI)) in environmental and biological samples by MSPE combined with FAAS using Fe3O4@SiO2-AEAPS as extractant. Various parameters affecting MSPE were optimized systematically. Under the optimized conditions, an enrichment factor 100 and the determination limit 0.66μg/L were found. The proposed method has been successfully applied to the determination of trace chromium species in environmental and biological samples.(2) A method has been developed for the determination of trace chromium species (Cr(Ⅲ) and Cr(Ⅳ)) in environmental and biological samples by MSPE combined with FAAS using Fe3O4@ZrO2 as extractant. Various parameters affecting MSPE were optimized systematically. Under the optimized conditions, an enrichment factor 25 and the determination limit 0.69μg/L were found. The proposed method has been applied to the determination of trace chromium species in environmental and biological samples, and a well result was received.(3) A method has been developed for the determination of trace chromium species (Cr(Ⅲ) and Cr(Ⅵ)) in environmental and biological samples by MSPE combined with FAAS using Fe3O4@APDC as extractant. Various parameters affecting MSPE were optimized systematically. Under the optimized conditions, an enrichment factor 8.3 and the determination limit 3.13μg/L were found. The proposed method has been successfully applied to the determination of trace chromium species in environmental and biological samples, demonstrating the feasibility and reliability of the proposed method.