title: Modified mesoporous silica materials for on-line separation and preconcentration of hexavalent chromium using a microcolumn coupled with flame atomic absorption spectrometry.
abstract: A modified SBA-15 mesoporous silica material NH(2)-SBA-15 was synthesized successfully by grafting γ-aminopropyl-triethoxysilane. The material was characterized using transmission electron microscopy (TEM) and Fourier transform infrared/Raman (FT-IR/Raman) spectroscopy, and used for the first time in a flow injection on-line solid phase extraction (SPE) coupled with flame atomic absorption spectrometry (FAAS) to detect trace Cr (VI). Effective sorption of Cr (VI) was achieved at pH 2.0 with no interference from Cr (III) and other ions and 0.5 mol L(-1) NH(3)·H(2)O solution was found optimal for the complete elution of Cr (VI). An enrichment factor of 44 and was achieved under optimized experimental conditions at a sample loading of 2.0 mL min(-1) sample loading (300 s) and an elution flow rate of 2.0 mL min(-1) (24s). The precision of the 11 replicate Cr (VI) measurements was 2.1% at the 100 μg L(-1) level with a detection limit of 0.2 μg L(-1) (3s, n=10) using the FAAS. The developed method was successfully applied to trace chromium determination in waste water. The accuracy was validated using a certified reference material of riverine water (GBW08607).
authors.affiliation: Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, PR China. wangzheng@mail.sic.ac.cn
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Fang
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Ling-Xia
authors.initials: LX
authors.lastname: Zhang
authors.forename: Rong
authors.initials: R
authors.lastname: Qian
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Hai-Yun
authors.initials: HY
authors.lastname: Qu
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Du
mesh_terms: D064753:Ammonium Hydroxide; D002857:Chromium / Q000032:analysis*; D017022:Flow Injection Analysis; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*; D013054:Spectrophotometry, Atomic / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D006878:Hydroxides; C509969:SBA-15; D012821:Silanes; D014874:Water Pollutants, Chemical; D014867:Water; D002857:Chromium; C074702:chromium hexavalent ion; D064753:Ammonium Hydroxide; D012822:Silicon Dioxide