THE EFFECT OF POLYMERIC SUPPORTS AND METHODS OF IMMOBILIZATION ON THEPERFORMANCE OF AN OPTICAL COPPER(II)-SENSITIVE MEMBRANE-BASED ON THE COLOURIMETRIC REAGENT ZINCON

A comparative study on the effect of different immobilization methods and matrix materials on the performance of copper(II)-sensitive membra ne layers is presented. The indicator dye Zincon was immobilized in hy drophilic and hydrophobic polymers by various methods including: (a) p hysical entrapment of the Zincon-tetraoctylammonium ion pair in plasti cized PVC, hydrogel, polystyrene, ethyl cellulose, poly-HEMA, AQ-polym er and in sol-gel glass; (b) electrostatic immobilization on an anion exchanger cellulose; and (c) covalent immobilization on cellulose via a sulfatoethylsulfonyl reactive group. The response to copper(II) ion was evaluated kinetically via the initial slope of the change in absor bance within 1 min. Layers made of hydrogel and PVC provide the highes t sensitivity, while covalent immobilization is the most reproducible one, and sol-gel layers display the best mechanical stability. (C) 199 8 Elsevier Science B.V. All rights reserved.