Coprecipitative Preconcentration of Cr(III), Pb(II), Zn(II), Cd(II) and Mn(II) Ions with Al(III) and Fe(III) Carriers and Chromotrope 2B Reagent and their FAAS Determination in Various Water and Food Samples

Coprecipitation methods using Al(III) and Fe(III) as carrier elements and chromotrope 2B as coprecipitative reagent were described for the preconcentration of Cr(III), Pb(II), Zn(II), Cd(II) and Mn(II) ions. The surface morphology of coprecipitants was examined by scanning electron microscopy (SEM). The optimum conditions for both coprecipitation methods, such as pH of the solution, amounts of carriers and reagent, sample volume and effect of interfering ions were investigated. Similar results were obtained for both carriers. The optimal pH was found at 9.0. The limits of detection (LOD) found were: 0.54 for Cr(III), 1.16 for Pb(II) and 0.08 mu g L-1 for Zn(II) when Al(III) carrier was used and 0.08, 0.17, 0.08 and 1.16 mu g L-1 for Cd(II), Mn(II), Zn(II) and Pb(II), respectively, when Fe(III) was the carrier. For the accuracy of the methods, the analysis of certified reference materials (TMDA 54.4 and TMDA 70 fortified lake waters and SRM 1578a rice flour) and recovery studies were performed. The method was applied for the determination of analytes in water (tap water, dam water and river water) and food (apricot, mint and macaroni) samples.