title: Determination of copper, iron, nickel and zinc in ethanol fuel by energy dispersive X-ray fluorescence after pre-concentration on chromatography paper.
abstract: This paper presents an alternative analytical method employing energy dispersive X-ray fluorescence (EDXRF) to determine copper, iron, nickel and zinc ions in ethanol fuel samples after a pre-concentration procedure. Our pre-concentration strategy utilizes analyte retention on cation exchange chromatography paper, a convenient substrate for direct EDXRF measurements. The repeatability, expressed in terms of RSD of standard solutions containing 0.25 μg mL(-1) of Cu, Fe, Ni and Zn, and calculated from fifteen consecutive measurements, was 2.5, 2.8, 3.0, and 2.7%, 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 13, 15, 15 and 12 μg L(-1) for Cu, Fe, Ni and Zn, respectively. The proposed method was applied to Cu, Fe, Ni and Zn determination in hydrated ethanol fuel samples collected from different gas stations.
authors.affiliation: Instituto de Química-Universidade Federal da Bahia, Campus Universitário de Ondina, 40.170-115-Salvador, Bahia, Brazil. lsgt@ufba.br
authors.forename: Leonardo Sena Gomes
authors.initials: LS
authors.lastname: Teixeira
authors.forename: Elenir Souza
authors.initials: ES
authors.lastname: Santos
authors.forename: Luana Sena
authors.initials: LS
authors.lastname: Nunes