title: A novel flow injection chemiluminescence determination of Cr(VI) with Dichlorotris(1,10-phenanthroline)ruthenium(II).
abstract: A selective novel reverse flow injection system with chemiluminescence detection (rFI-CL) for the determination of Cr(VI) in presence of Cr(III) with Dichlorotris (1,10-phenanthroline)ruthenium(II), (Ru(phen)(3)Cl(2)), is described in this work. This new method is based on the oxidation capacity of Cr(VI) in H(2)SO(4) media. First, the Ruthenium(II) complex is oxidized to Ruthenium(III) complex by Cr(VI) and afterwards it is reduced to the excited state of the Ruthenium(II) complex by a sodium oxalate solution, emitting light inside the detector. The intensity of chemiluminescence (CL) is proportional to the concentration of Cr(VI) and, under optimum conditions, it can be determined over the range of 3-300 μg L(-1) with a detection limit of 0.9 μg L(-1). The RSD was 8.4% and 1.5% at 5 and 50 μg L(-1), respectively. For the rFI-CL method various analytical parameters were optimized: flow rate (1 mL min(-1)), H(2)SO(4) carrier concentration (20% w/V), Ru(phen)(3)Cl(2) concentration (5mM) and sodium oxalate concentration (0.1M). The effect of Cr(III), Fe(III), Al(III), Cd(II), Zn(II), Hg(II), Pb(II), Ca(II) and Mg(II), was studied. The method is highly sensitive and selective, allowing a fast, on-line determination of Cr(VI) in the presence of Cr(III). Finally, the method was tested in four different water samples (tap, reservoir, well and mineral), with good recovery percentage.
authors.affiliation: Faculty of Chemistry, University of Havana, 10400 Havana, Cuba.
authors.forename: M D
authors.initials: MD
authors.lastname: Luaces
authors.forename: N C
authors.initials: NC
authors.lastname: Martínez
authors.forename: M
authors.initials: M
authors.lastname: Granda
authors.forename: A C
authors.initials: AC
authors.lastname: Valdés
authors.forename: C
authors.initials: C
authors.lastname: Pérez-Conde
authors.forename: A M
authors.initials: AM
authors.lastname: Gutiérrez