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London, United Kingdom

Vortex-assisted dispersive liquid-liquid microextraction using methyl benzoate as an alternative extraction solvent for extracting and preconcentrating three benzimidazole fungicides (i.e., carbendazim, thiabendazole, and fluberidazole) in environmental water samples before high-performance liquid chromatographic analysis has been developed. The selected microextraction conditions were 250 μL of methyl benzoate containing 300 μL of ethanol, 1.0% w/v sodium acetate, and vortex agitation speed of 2100 rpm for 30 s. Under optimum conditions, preconcentration factors were 14.5-39.0 for the target fungicides. Limits of detection were obtained in the range of 0.01-0.05 μg/L. The proposed method was then applied to surface water samples and the recovery evaluations at three spiked concentration levels of 5, 30, and 50 μg/L were obtained in the range of 77.4-110.9% with the relative standard deviation <7.4%. The present method was simple, rapid, low cost, sensitive, environmentally friendly, and suitable for the trace analysis of the studied fungicides in environmental water samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA.

Kabilaphat J.,Materials Chemistry Research Center | Khaorapapong N.,Materials Chemistry Research Center | Saito K.,Waseda University | Ogawa M.,Institute of Chemical Technology
Applied Clay Science | Year: 2015

Novel hybrids composed of mixed metal sulfides (manganese sulfide and zinc sulfide (MnS/ZnS) or cadmium sulfide (MnS/CdS), as well as zinc sulfide and cadmium sulfide (ZnS/CdS)) with montmorillonite were synthesized by solid-solid reactions between the ion exchanged montmorillonite and sodium sulfide. The products were characterized by powder X-ray diffraction, transmission electron microscopy, as well as Raman, UV-visible and photoluminescence spectroscopies. The Raman spectra indicated the presence of manganese sulfide, zinc sulfide, and/or cadmium sulfide in the products. The absorption onsets observed at 318-366. nm for MnS/ZnS@montmorillonite, at 330-521. nm for MnS/CdS@montmorillonite, and at 360-480. nm for ZnS/CdS@montmorillonite indicated the formation of two metal sulfides in the interlayer spaces. In comparison with those of bulk MnS (340. nm), ZnS (360. nm) and CdS (525. nm), the absorption onsets owing to both metal sulfides were blue shifted probably due to quantum confinement effect, suggesting that the products are composed of nanometer sized sulfide particles. The photoluminescence bands owing to manganese sulfide (416 and 435. nm), zinc sulfide (413 and 440. nm), and cadmium sulfide (451 and 469. nm) were also seen. The emission intensity of MnS/ZnS@montmorillonite was stronger than that of MnS/CdS@montmorillonite, probably due to the higher band gap energy of MnS/ZnS system that resulted in the increase of recombination of excitons. © 2015 Elsevier B.V.

Chew C.K.T.,Materials Chemistry Research Center | Salcianu C.,Johnson Matthey | Bishop P.,Johnson Matthey | Carmalt C.J.,Materials Chemistry Research Center | Parkin I.P.,Materials Chemistry Research Center
Journal of Materials Chemistry C | Year: 2015

Noble nanoparticle-metal oxide composites attract research interest due to their unique combination of properties. We report the successful combination of gold nanoparticles (AuNPs) and F-doped SnO2 composites by layering, producing films that demonstrate unique and interesting optoelectronic properties - high visible transparency, electrical conductivity and with additional plasmonic effects. Both of the layers were deposited by aerosol assisted chemical vapour deposition (AACVD) onto heated glass substrates. Four distinctive sets of films were prepared and analysed consisting of: gold nanoparticles, F-doped SnO2 (FTO), a layer of gold nanoparticles on FTO and an FTO layer on gold nanoparticles. The sizes of the AuNPs were shown to depend on the precursor concentration used. Layered Au:FTO composite films have an attractive blue colouration from the surface plasmon resonance (SPR) of the AuNPs yet have high transparency in the visible region and are electrically conducting, comparable to commercial FTO. © The Royal Society of Chemistry 2015.

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