Speciation Analysis Of Mercury By Modified Silica Gel

The toxicological and environmental effects of mercury compounds have become of increasing concern with regard to human health and the global ecosystem. The toxicity of mercury is highly dependent on its chemical form. Methylmercury, the most toxic species of mercury normally found in environmental and biological material, is of particular concern because of its accumulation as it passes through the food chain. Accordingly, the rapid and sensitive determination of mercury species in addition to total mercury is highly essential for the interpretation of their biochemical behavior or assessment of the potential danger.Firstly, silica gel was reacted with tetraethyl orthosilicate by refluxing 12 hours in anhydrous toluene, then the 1,5-diphenylcarbazon grafted silica gel was synthesize by using the production of the fist process and 1,5-diphenylcarbazone. Then the analytical characteristics of the 1,5-diphenylcarbazone grafted silica gel are studied using visible spectrophotometry, such as stability, the condition of preconcentration and separation for inorganic mercury and methyl mercury, the quantity of absorption and the speed of enrichment.Secondly, the modified silica gel was packed in a mico-column linked with flow injection and atomic fluorescence spectrum. Then it was found that the mico-column packed with grafted silica gel could separate and enrich the trace inorganic and organic mercury in different pH. Moreover, the grafted silica gel could enrich the mercury only in a solution contained many different kinds of ions. At last, this method was developed successfully for determination of methyl mercury in the codfish, small yellow croaker, sashimi, silvery pomfret dogfish and so on.The experiment results show that these methods could separate and enrich the inorganic mercury and methyl mercury in different condition. Moreover this grafted silica gel has quite good enrichment capability for inorganic mercury and organic mercury, each absorption quantity is 53mg·g-1 and 45mg·g-1. Based on these results, new methods for the determination of mercury speciation have been established with high sensitivity and selectivity.