Chemical pretreatment of silver wire containing copper for preparation of silver/silver sulfide ion-selective electrode

Abstract

The silver/silver sulfide ion selective electrode (ISE) has been produced in a variety of forms. While the membrane type reportedly exhibits superior performance characteristics in comparison to the type derived from solid silver, the latter offers decided advantages in terms of cost and convenience. We wish to report that a microscale silver/silver sulfide ISE can be readily prepared from silver wire (0, 7 mm diameter) which contains 2, 5-6% Cu (w/w) by exposing the wire to a deaerated aqueous solution of sodium sulfide, ascorbic acid, and etbylenediaminetetraacetic acid (SAOB-H) for 2 days. Although this procedure is similar to one reported in the manufacturers' literature, it is significant that a successful ISE could not be prepared by this technique if pure silver (99.99%) was used or if the SAOB-II solution was not deaerated. Finally, the performance of electrodes obtained in this manner was basically indistinguishable from that of a commercially available electrode of the membrane type.