Electrochemical evaluation of polysiloxane-immobilized amine ligands for the accumulation of copper(II) species

Accumulation of copper(II) by amine ligands immobilized by covalent binding to silica-based materials was examined by electrochemistry at modified car bon paste electrodes. Three samples were compared: a silica gel grafted wit h aminopropyle groups, an organic-inorganic hybrid resulting from the conde nsation of tetra-ethoxysilane and aminopropyle-triethoxysilane and a mesopo rous pure silica MCM-41 material grafted with aminopropyle groups. These so lids were characterized by diffuse reflectance infrared Fourier transform ( DRIFT) spectroscopy, acid-base titration, N-2 adsorption and for their abil ity to accumulate copper(II) species. Electrochemical detection was achieve d after accumulation of copper(II) at open circuit and both preconcentratio n and detection steps were optimized by varying pH, preconcentration time a nd the composition of the detection medium. Results are discussed with resp ect to the nature of the modified silicas. (C) 1999 Elsevier Science Ltd. A ll rights reserved.