| 1. |
- Hu, Xialin, et al.
(författare)
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DEVELOPMENT OF NEGLIGIBLE DEPLETION HOLLOW FIBER-PROTECTED LIQUID-PHASE MICROEXTRACTION FOR SENSING FREELY DISSOLVED TRIAZINES
- 2009
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 28:2, s. 231-238
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Tidskriftsartikel (refereegranskat)abstract
- A new sampling method, termed negligible depletion hollow fiber-protected liquid-phase microextraction, was developed for sensing the freely dissolved concentration (C free) and evaluating the availability of atrazine (ATR), desethyl atrazine (DEA), and simazine (SIM) in water. The sampling device was prepared by impregnating 1-octanol to both the pores and the lumen of a piece of polypropylene microporous hollow fiber membrane. After equilibrium and negligible depletion extraction, the 1-octanol in the lumen of the hollow fiber (10 mu l) was collected for determination of triazines. Determination of C free and the distribution coefficient to 1-octanol (D-OW) can be performed with this technique. A wide linear working range (1-200 mu g/L) and low detection limits (0.1-1 mu g/L) were obtained for triazines. Measured log D-OW values of DEA (1.44 +/- 0.04), SIM (2.06 +/- 0.06), and ATR (2.33 +/- 0.05) agreed well with those reported in the literature. The measured D-OW values were independent of the chemical concentration and sample pH (pH 3-10) and negligibly affected by the sample salinity (0-500 mM), suggesting that environmentally relevant pH and salinity have no significant effects on the availability of triazines. Although a slight (<= 31%) increase of C free was observed, one-way analysis of variance indicated the C free of triazines were not significantly affected by the presence of Aldrich humic acid, Acros humic acid, and bovine albumin V (dissolved organic carbon [DOC], 0-100 mg/L). From 3 to 36% of the spiked triazines, however, were found to associate with the dissolved organic matter (DOM) in surface-water samples (DOC, 32.0-61.9 mg/L), suggesting the origin of the DOM is a key parameter in determining its association with and, thus, the availability of triazines.
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| 2. |
- Yin, Yongguang, et al.
(författare)
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Possible alkylation of inorganic Hg(II) by photochemical processes in the environment
- 2012
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 88:1, s. 8-16
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Tidskriftsartikel (refereegranskat)abstract
- The methylation of inorganic Hg by anaerobic bacteria in aquatic environments is considered to be the major pathway for methylmercury (MeHg) production. However, recent research has suggested that abiotic or chemical methylation by humic substances and other low-molecular-weight organic compounds in natural environments is also possible. Here, the aqueous photo-transformation of Hg(2+) to organomercurials was investigated in the presence of ketones, aldehydes and low molecular weight organic acids under UV irradiation. MeHg and/or ethylmercury (EtHg) were identified as the main organomercurial products by multiple analytical techniques, including chromatography-atomic spectrometry and molecular mass spectrometry and further confirmed by stable isotope tracer experiments. The yield of organomercurials was markedly influenced by pH, NaCl concentration, alkylation donor concentration and the presence of chelating ligands in the aqueous solution. Electron paramagnetic resonance spectrometry demonstrated that the radical reaction was not the predominating alkylation pathway, although methyl radicals were detected in the photo-alkylation procedure. A mechanism based on intra-molecular alkyl transfer in the Hg(2+)-low-molecular-weight organic compound complex is proposed. The present work helps us better understand of MeHg and EtHg photo-generation in natural environments.
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