title: Graphene oxide-TiO2 composite solid phase extraction combined with graphite furnace atomic absorption spectrometry for the speciation of inorganic selenium in water samples.
abstract: In this paper, a method of graphene oxide (GO)-TiO2 composite solid phase extraction followed by graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the speciation of inorganic selenium in environmental waters. The adsorption behavior of inorganic Se(IV) and Se(VI) on the GO-TiO2(1:1) composite was investigated. It was found that Se(IV) was quantitatively retained on the GO-TiO2 composites within a wide pH range of 0.5-10, while Se(VI) was quantitatively adsorbed on GO-TiO2(1:1) composite at pH 0.5-2, and no obvious adsorption of Se(VI) within the pH range of 4-10 was found. By selecting pH 6.0, Se(IV) could be easily determined. After reduction of Se(VI), total Se was determined by the proposed method, and Se(VI) was calculated as the difference between the total Se and Se(IV). The factors affecting the separation/preconcentration of Se(IV) and Se(VI) were studied. Under the optimum conditions, the isothermal adsorption of Se(IV) on the GO-TiO2(1:1) composite fitted Langmuir model; a linear range over 0.1-12ngmL(-1) was obtained. The limit of detection (LOD) and precision of the method for Se(IV) was 0.04ngmL(-1) and 9.4% (cSe(IV)=0.5ngmL(-1), n=7), respectively. In order to verify the accuracy of the method, a standard water sample (GSBZ50031-94) was analyzed, and the determined value was in a good agreement to the certified value. The established method was applied to inorganic Se speciation in environmental water samples and the recovery of 87.4-102% was obtained for the spiked samples.
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China.
authors.forename: Beibei
authors.initials: B
authors.lastname: Chen
authors.affiliation: College of Chemistry and Environmental Engineering, Hubei Institute for Nationalities, Enshi 445000, China.
authors.forename: Shaowei
authors.initials: S
authors.lastname: Wu
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China. Electronic address: heman@whu.edu.cn.
authors.forename: Man
authors.initials: M
authors.lastname: He
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Hu
keywords: Environmental water; GO–TiO(2) composite; Graphite furnace atomic absorption spectrometry; Se(IV)/Se(VI) speciation; Solid phase extraction