Copper solvent exchange data

The results of Cu loadings observed for samples prepared by ion exchange of silica with [Cu(en)2] appear to be confirmed by the recent data reported by Toupance, et al on their attempts to prepared Cu/silica solids. They reported Cu loadings < 2 wt% when the cation was the copper ethylenediamine however, they did not mention the use of a co-solvent. 

Simplicity, rapidity, and specificity have caused adoption of atomic absorption as a standard method in water analysis. Often solutions must be concentrated prior to measurement. Freezing, evaporation, ion exchange, and solvent extraction techniques have been reported. This paper describes a method for concentrating ferric iron, copper, zinc, cadmium, and lead using sodium diethyldithiocarbamate and methyl isobutyl ketone. Data shows increase in sensitivity caused by (1) concentrating effect of extraction, and (2) choice of the ketone solvent in preference to water. Recovery data on various industrial waters indicate that the method is reliable, reproducible, and accurate. 

The suppressor column, as well as enabling mercury to be determined, was also advantageous with respect to determination of copper, nickel, and in particular cobalt. Unfortunately, use of the suppressor column is detrimental to the determination of Cd(dtc)2 whose response disappears and Pb(dtc)2, whose response is considerably reduced. Presumably, these complexes are significantly retained as anionic complexes on the ion exchange suppressor. These data support conclusions obtained from voltammetric data in a conventional electrochemical cell, that the cadmium and lead complexes exist in anionic as well as neutral forms in the chromatographic solvent. Limits of detection for the simultaneous determination of lead, cadmium, mercury, copper, nickel and cobalt are given in Table 7.2. 

---