Characterization and application of silylated substrates for the preconcentration of cations

Abstract

Chelating functional groups immobilized on silica and controlled pore glass beads are used to preconcentrate cations from aqueous solution in the concentration region of ng ml −1. The functional groups are chemically bonded to the substrates by silylation reagents which may be employed as received or further modified. For example, commercially available 1,2-diamines may be used or converted to the dithiocarbamate after immobilization. This report includes studies of ionic strength and sodium chloride effects on the recovery of transition metal ions. Batch extraction of transition metal ions is accomplished with silica as the substrate for solutions containing transition metal ions at μg ml −1 concentrations. Column extraction of solutions pumped at 50 ml min −1 is accomplished at concentrations of 25 ng ml −1. Recovery is good in both cases. The cations were determined directly on pelletized substrates by x-ray fluorescence. However, the ions may be eluted from the substrate and determined by other methods. Examples of determinations of several cations in lake water and high-purity industrial water are given.