Analytical and Bioanalytical Chemistry

, Volume 390, Issue 5, pp 1355–1359 | Cite as

Characterization of optimized Na+ and Cl liquid membranes for use with extracellular, self-referencing microelectrodes

  • Mark A. MesserliEmail author
  • Ira Kurtz
  • Peter J. S. Smith
Technical Note


Self-referencing with ion-selective microelectrodes (ISMs) is a useful approach for monitoring near-real-time ion flux near single cells and across epithelia. While ISMs for H+, Ca2+, and K+ have been optimized for use with self-referencing, ISMs for two other primary inorganic ions, Na+ and Cl, have not. In this study, we have characterized ISMs based on three Na+ ionophores (I, VI, and X) and one Cl ionophore to assess their suitability for use with self-referencing. ISMs constructed with Na+ ionophore VI have short response times (≈100 ms) but possess nearly an order of magnitude less selectivity for Na+ over K+ than ISMs constructed with Na+ ionophore X. The Na+ ionophore X mixture was enhanced to give it a shorter response time while not compromising its selectivity. A Cl-selective microelectrode was constructed and characterized with superior anionic selectivity compared with previously reported Cl ISMs used with self-referencing. This Cl-selective microelectrode, however, has a relatively slow response time (≈3 s), thus requiring changes to the self-referencing protocol. Self-referencing with these ISMs will enable near-real-time ion flux measurements for Na+ and Cl.


Ion-selective microelectrode Self-referencing Na+ Cl 



This research was funded by NIH-NCRR grant P41 RR001395 to P.J.S. Smith and by NIH Grants DK077162, DK07789, and DK058563, and DK063125 to I. Kurtz.


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Mark A. Messerli
    • 1
    Email author
  • Ira Kurtz
    • 2
  • Peter J. S. Smith
    • 1
  1. 1.BioCurrents Research Center, Program in Molecular PhysiologyMarine Biological LaboratoryWoods HoleUSA
  2. 2.Division of NephrologyDavid Geffen School Medicine at UCLALos AngelesUSA

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