PVC-MATRIX MEMBRANE ION-SELECTIVE SENSORS FOR GOLD DETERMINATION IN CYANIDE SOLUTIONS

Potentiometric sensors with conventional plasticized poly(vinyl-chlori de) membranes, sensitive to the dicyanoaurate ion, and two kinds of tr ansducers (an encapsulated pH-sensitive ion-selective field-effect tra nsistor (ISFET) with Ta2O5 as a gate insulator and a silver coated cer amic substrate (AgCer)), were studied. The application of an intermedi ate hydrophobic polymer layer between the ion sensitive membrane and t he transducer surface leads to a dramatical rise of the ISFET life tim e and, on the contrary, to a decrease of AgCer based sensor durability from 6 months down to 5-6 weeks. The effects of membrane plasticizer and thickness on the performance, selectivity and durability of these sensors were studied. (C) 1997 Elsevier Science B.V.