Polyaniline Nanoparticle-Based Solid-Contact Silicone Rubber Ion-Selective Electrodes for Ultratrace Measurements

摘要

Silicone rubber (SR)-based solid-contact ion-selectivenelectrodes (ISEs) have been prepared for the first timenwith an electrically conducting polymer as the solidcontactn(SC) layer. The Ca2+- and Ag+-selective electrodesnwere based on the ionophores ETH 1001 andno-xylylenebis(N,N-diisobutyl dithiocarbamate), respectively,nintegrated in room temperature vulcanizingnsilicone rubber (RTV 3140). The SC consisted of anpolyaniline nanoparticle dispersion, which was foundnto considerably lower the impedance of the SCISEs inncomparison to the SR-based coated wire electrodesn(CWE). For the CaSCISEs, the bulk membrane resistancendecreased from 700 MΩ (CaCWE) to 35 MΩ.nBoth the Ca2+- and Ag+-selective SCISEs exhibitednnanomolar detection limits with fast Nernstian responsesndown to 10-8 M. The potential response of thenSCISEs was not influenced by light. The selectivitiesnof the CaSCISEs were similar and for the AgSCISEnbetter than their plasticized PVC-based analogues.nThus, SR seems to be a viable alternative to PVCnmembranes in ISE applications that require low waternuptake, good adhesion, and robust and fast potentialnresponses at submicromolar sample concentrations.