Preconcentration, Speciation And Determination Of Ultra Trace Amounts Of Mercury By Modified Octadecyl Silica Membrane Disk/electron Beam Irradiation And Cold Vapor Atomic Absorption Spectrometry

摘要

Mercury (Ⅱ) and methyl mercury cations at the Sub-ppb level were adsorbed quantitatively from aqueous solution onto an octadecyl-bonded silica membrane disk modified by 2-[(2-mercaptophyenylimino)methyl) phenol (MPMP). The trapped mercury was then eluted with 3 ml ethanol and Hg2* ion was directly measured by cold vapor atomic absorption spectrometry, utilizing tin (Ⅱ) chloride. Total mercury (Hgt) was determined after conversion of MeHg~+ into Hg~(2+) ion by electron beam irradiation. A sample volume of 1500 ml resulted in a preconcentration factor of 500 and the precision for a sampling volume of 500 ml at a concentration of 2.5 μg l~(-1) (n = 7) was 3.1 %. The limit of detection of the proposed method is 3.8 ng l~(-1). The method was successfully applied to analysis of water samples, and the accuracy was assessed via recovery experiment.