Solid-contact ion-selective electrodes (SC-ISEs) can exhibit very low detection limits and, in contrast to conventional ISEs, do not require an optimization of the inner filling solution. This work shows that subnanomolar detection limits can also be achieved with SC-ISEs with three-dimensionally ordered macroporous (3DOM) carbon contacts, which have been shown recently to exhibit excellent long-term stabilities and good resistance to the interferences from oxygen and light. The detection limit of 3DOM carbon-contacted electrodes with plasticized poly-(vinyl chloride) as membrane matrix can be improved with a high polymer content of the sensing membrane, a large ratio of ionophore and ionic sites, and conditioning with a low concentration of analyte ions. This permits detection limits as low as 1.6∈×∈10 -7 M for K + and 4.0∈×∈10 -11 M for Ag +.
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation (NSF) (CTS-0428046), the National Institute of Health (R01 EB005225-01), the Office of Naval Research (ONR, Grant N00014-07-1-0608), and the MRSEC program of the NSF (DMR-0212302), which supports the University of Minnesota Characterization Facility. MAF thanks 3M for a Science & Technology Fellowship. MMJ and NDP acknowledge the NSF/Lando summer undergraduate research fellowship program of the University of Minnesota (CHE-0552622).
- Detection limit
- Solid-contact ion-selective electrode
- Three-dimensionally ordered macroporous (3DOM) carbon