title: Novel on-line sequential preconcentration system of Cr(III) and Cr(VI) hyphenated with flame atomic absorption spectrometry exploiting sorbents based on chemically modified silica.
abstract: In the present study, a flow injection system using dual mini-columns, SiO(2)/Al(2)O(3)/TiO(2) and silica gel functionalized with [3-(2-aminoethylamino)propyl] trimethoxysilane (SiO(2)/AAPTMS) for the sequential preconcentration of Cr(III) and Cr(VI), respectively, from water samples with FAAS detection was proposed. A two-level full factorial design (2(4)) and desirability function were employed for the optimization of variables related to the system performance. The detection limits of 0.66 and 0.27 μg L(-1) for Cr(III) and Cr(IV), respectively, were obtained under the optimized preconcentration conditions (flow rate of 7.0 mL min(-1)), pH 5.0, buffer concentration (acetate buffer) of 0.01 mol L(-1), and eluent (2.5 mol L(-1) HCl) flow rate of 5.0 mL min(-1). The other parameters including preconcentration factor (PF), consumptive index (CI), and concentration efficiency (CE) were found to be 17.62/32.98, 1.13/0.6 mL, and 6.2/11.54 min(-1) for Cr(III)/Cr(VI), respectively. The developed method was applied to the Cr(III) and Cr(VI) determination in water samples [tap, lake and mineral water, artificial saliva and parenteral solutions (physiological serum, water for injection, and glucose physiological solution)]. The method accuracy was checked by the analysis of standard reference materials (trace elements in water).
authors.affiliation: Programa de Pós-Graduação em Química da Universidade Federal de Uberlândia (UFU), Av. João Naves de Ávila 2121, Campus Santa Mônica, Uberlândia-MG, CEP 38400-902, Brazil. tarley@uel.br
authors.forename: César R T
authors.initials: CR
authors.lastname: Tarley
authors.forename: Giovana F
authors.initials: GF
authors.lastname: Lima
authors.forename: Danielle R
authors.initials: DR
authors.lastname: Nascimento
authors.forename: Alan R S
authors.initials: AR
authors.lastname: Assis
authors.forename: Emerson S
authors.initials: ES
authors.lastname: Ribeiro
authors.forename: Kristiany M
authors.initials: KM
authors.lastname: Diniz
authors.forename: Marcos A
authors.initials: MA
authors.lastname: Bezerra
authors.forename: Mariana G
authors.initials: MG
authors.lastname: Segatelli
mesh_terms: D053000:Analytic Sample Preparation Methods / Q000379:methods*; D002857:Chromium / Q000032:analysis* / Q000737:chemistry*; D017022:Flow Injection Analysis; D006863:Hydrogen-Ion Concentration; D015999:Multivariate Analysis; D012822:Silicon Dioxide / Q000737:chemistry*; D013054:Spectrophotometry, Atomic / Q000379:methods*; D013997:Time Factors
chemical_list: D002857:Chromium; C074702:chromium hexavalent ion; D012822:Silicon Dioxide