title: A new Cu(II)-5-(4-sulphophenylazo)-8-aminoquinoline complex used for copper determination in presence of gold and silver in water and mineral samples.
abstract: In this work, a characterization of reagent chromophore 5-(4-sulphophenylazo)-8-aminoquinoline [SPA] by IR and 1H RMN was carried out and a pK(a) value of 3.55+/-0.03 was found as well. An 1:2 stoichiometry for the Cu(II)-SPA complex was determined at pH 9 by Job and molar ratio methods. A value of 1.4 x 10(14) for the stability constant was also found. Based on the formation of this complex a new method for the copper determination in presence of gold and silver was developed by derivative spectrophotometry using a previous preconcentration on solid phase. In this method, the analytical measures were executed directly in the solid phase containing the complex. The Cu(II) reacts with the reagent chromophore SPA previously retained in the anionic exchange DEAE Sephadex A25. In this determination, the first derivative at 605 nm was used. The quantification range was between (3.2+/-0.3 x 10(-1)) x 10(-8) and (94.4+/-0.9) x 10(-8) mol L(-1) (3.2+/-0.3 x 10(-1)) x 10(-8), and (94.4+/-0.9) x 10(-8) mol L(-1). The repeatability expressed as RSD was between 1.1 and 2.0%. The method was applied successfully for the copper determination in mineral residuals and natural water samples. The results were consistent with those provided by ICP-mass spectrometry.
authors: Department of Chemistry, Faculty of Sciences, University of Chile, PO Box 653, Santiago, Chile.
authors: Libby
authors: L
authors: Morales
authors: M Inés
authors: MI
authors: Toral
authors: M José
authors: MJ
authors: Alvarez
mesh_terms: D000634:Aminoquinolines / Q000737:chemistry*; D003300:Copper / Q000032:analysis* / Q000737:chemistry; D003637:DEAE-Dextran / Q000031:analogs & derivatives / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D012834:Silver / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D000634:Aminoquinolines; D014874:Water Pollutants, Chemical; C030237:DEAE-sephadex A-25; D012834:Silver; D006046:Gold; D003300:Copper; D003637:DEAE-Dextran