Design, synthesis, and application of chelating polymers for separation and determination of trace and toxic metal ions. A green analytical method*

A green analytical method was developed for separation and preconcentration of trace amounts of copper from aqueous samples using aurin tricarboxylic acid-immobilized silica gel (ATA-SG). This was done by determining chemical speciation and stability constant of Cu-ATA complex. The pH-metric studies indicate strong complexation of Cu with ATA (log βCu2ATA = 19.56). Species distribution curve for Cu-ATA complex indicates almost 100% complexation of copper, with ATA forming Cu2ATA as the predominant species. Considering the selectivity and strong interaction of ATA toward copper, ATA was immobilized on the polymeric matrix of silica gel, and the conditions were optimized for the uptake of copper from the aqueous solutions. The uptake of Cu ions by ATA-SG was studied both by batch and column methods. The method was developed for the estimation of trace amounts of copper in various samples. Molecular modeling studies were also performed on ATA-immobilized silica gel for gaining an insight into the active structure of ATA on the silica surface.