Pre-concentration of Cd, Co, Cu, Ni and Zn using different off-line ion exchange procedures followed by the inductively coupled plasma atomic emission spectrometric detection

The chelating resin Metalfix Chelamine and the strong cation exchanger Dowex 50W-X4 were studied for the off-line pre-concentration of Cd, Co, Cu, Ni and Zn prior to the measurements by the inductively coupled plasma atomic emission spectrometry. Different approaches to the recovery of metals were investigated and compared: the elution with the solutions of HCl and HNO₃ and the decomposition of the resins with the adsorbed metals by means of the high-pressure microwave assisted system. Due to the problem arisen with the quantitative elution of the metals from the resins, which bound the analytes very strongly, the procedure of the digestion of the resin after the pre-concentration step was preferable to the plain elution, giving significantly better recoveries of the metals. The chosen procedure was applied for the determination of traces of Cd, Co, Cu, Ni and Zn in beer. For the analysis, mineralised and not mineralised beer samples were treated with Dowex 50W-X4 resin in order to assess the total content of Cd, Co, Cu, Ni and Zn and the fraction of the cationic labile species of the analytes, respectively. The increase in the sensitivity allowed determination of the selected metals at concentrations of order of 1 ng ml⁻¹. The accuracy of the entire procedure was verified by the recovery test in the spiked samples of beer. The proposed method provides full recovery for Cd (101±1%), Co (99±2%) and Zn (106±3%) and reasonably high recovery for Cu (84±1%) and Ni (89±1%).     

Application of Metalfix Chelamine prior to the determination of noble metals by the inductively coupled plasma atomic emission spectrometry

Metalfix Chelamine chelating resins of two different bead sizes (150-300 and 40-80 μm) were examined and compared regarding their application for sorption of Au, Ir, Pd, Pt, Rh and Ru ions from medium of HCl, HNO₃ and mixtures of HCl and HNO₃. The quantitative enrichment of Au, Ir, Pd and Pt was established for the resin of 150-300 μm particle size and for solutions acidified with HCl and HNO₃ (3:1) up to the concentration of 0.50 mol l⁻¹. In the case of Rh and Ru, the uptake of these metals by the resin was lower than 50%. For the elution, solutions of different reagents, i.e. HCl, HNO₃, KCN, KI, KSCN and (NH₂)₂CS, were studied with respect to the complete release of the analytes retained by the resin. In addition, influence of various base metals, i.e. Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, on the retention of the noble metals was investigated. Under the selected conditions for the retention and elution of Au, Ir, Pd and Pt, the analytical performance of the proposed pre-concentration procedure was evaluated and it was applied to the determination of these noble metals in anodic sludge sample.