title: Simultaneous determination of copper and iron in automotive gasoline by X-ray fluorescence after pre-concentration on cellulose paper.
abstract: This paper proposes an alternative analytical method using energy dispersive X-ray fluorescence (EDXRF) to determine Fe and Cu in gasoline samples. In the proposed procedure, samples were distilled and the distillation residues were spotted on cellulose paper disk to form a uniform thin film and to produce a homogeneous and reproducible interface to the XRF instrument. The disks were dried at 60 degrees C for 20min and copper and iron were determined directly in the solid phase at 6.40 and 8.04keV, respectively. The calibration curves showed linear response in the 20-800mugL(-1) concentration range of each metal. The precisions (repeatability) calculated from 15 consecutive measurements and defined as the coefficient of variation of solutions containing 100mugL(-1) of Fe and Cu were 7.8 and 8.1%, respectively. The limits of detection (LOD), defined as the analyte concentration that gives a response equivalent to three times the standard deviation of the blank (n=10), were found to be 10 and 15mugL(-1) for Fe and Cu, respectively. The proposed method was applied to copper and iron determination in gasoline samples collected from different gas stations.
authors.affiliation: Departamento de Engenharia e Arquitetura, Universidade Salvador-UNIFACS, Av. Cardeal da Silva 132, 40.220-141 Salvador-BA, Brazil.
authors.forename: Leonardo S G
authors.initials: LS
authors.lastname: Teixeira
authors.forename: Rodrigo B S
authors.initials: RB
authors.lastname: Rocha
authors.forename: Eledir V
authors.initials: EV
authors.lastname: Sobrinho
authors.forename: Paulo R B
authors.initials: PR
authors.lastname: Guimarães
authors.forename: Luiz A M
authors.initials: LA
authors.lastname: Pontes
authors.forename: Josanaide S R
authors.initials: JS
authors.lastname: Teixeira