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Response mechanism of polymer membrane-based potentiometric polyion sensors.
Anal Chem 1994; 66(14):2250-9AC

Abstract

The potentiometric response mechanism of a previously reported polymer membrane-based electrode sensitive to the polyanion heparin is established. Based on transport and extraction studies, the heparin response is attributed to a nonequilibrium change in the phase boundary potential at the sample/membrane interface. While true equilibrium polyion response, obtained for low heparin concentrations only after very long equilibration times (> 20 h), yields the expected Nernstian response slope of < 1 mV/decade, the observed large and reproducible EMF response to clinically relevant heparin concentrations (approximately 10(-7) M) during typical measurement periods (2-5 min) is ascribed to a steady-state kinetic process defined by the flux of the polyion both to the surface and into the bulk of the polymer membrane. A model describing this nonequilibrium response is presented. With this model, the uniqueness of the polymer membrane composition (e.g., very low plasticizer content, strictly controlled cationic site concentration, etc.) required to achieve analytically useful heparin response becomes clear. Practical working conditions and limitations of the sensor are discussed. To support the generality of the steady-state model proposed, corresponding EMF response data for a newly developed membrane electrode sensitive to a polycationic protein (protamine) are also presented. It is shown that the protamine-responsive membrane electrode appears to operate via the exact same kinetic mechanism as the heparin sensing system.

Authors+Show Affiliations

Department of Chemistry and College of Pharmacy, University of Michigan, Ann Arbor 48109.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8080104

Citation

Fu, B, et al. "Response Mechanism of Polymer Membrane-based Potentiometric Polyion Sensors." Analytical Chemistry, vol. 66, no. 14, 1994, pp. 2250-9.
Fu B, Bakker E, Yun JH, et al. Response mechanism of polymer membrane-based potentiometric polyion sensors. Anal Chem. 1994;66(14):2250-9.
Fu, B., Bakker, E., Yun, J. H., Yang, V. C., & Meyerhoff, M. E. (1994). Response mechanism of polymer membrane-based potentiometric polyion sensors. Analytical Chemistry, 66(14), pp. 2250-9.
Fu B, et al. Response Mechanism of Polymer Membrane-based Potentiometric Polyion Sensors. Anal Chem. 1994 Jul 15;66(14):2250-9. PubMed PMID: 8080104.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Response mechanism of polymer membrane-based potentiometric polyion sensors. AU - Fu,B, AU - Bakker,E, AU - Yun,J H, AU - Yang,V C, AU - Meyerhoff,M E, PY - 1994/7/15/pubmed PY - 1994/7/15/medline PY - 1994/7/15/entrez SP - 2250 EP - 9 JF - Analytical chemistry JO - Anal. Chem. VL - 66 IS - 14 N2 - The potentiometric response mechanism of a previously reported polymer membrane-based electrode sensitive to the polyanion heparin is established. Based on transport and extraction studies, the heparin response is attributed to a nonequilibrium change in the phase boundary potential at the sample/membrane interface. While true equilibrium polyion response, obtained for low heparin concentrations only after very long equilibration times (> 20 h), yields the expected Nernstian response slope of < 1 mV/decade, the observed large and reproducible EMF response to clinically relevant heparin concentrations (approximately 10(-7) M) during typical measurement periods (2-5 min) is ascribed to a steady-state kinetic process defined by the flux of the polyion both to the surface and into the bulk of the polymer membrane. A model describing this nonequilibrium response is presented. With this model, the uniqueness of the polymer membrane composition (e.g., very low plasticizer content, strictly controlled cationic site concentration, etc.) required to achieve analytically useful heparin response becomes clear. Practical working conditions and limitations of the sensor are discussed. To support the generality of the steady-state model proposed, corresponding EMF response data for a newly developed membrane electrode sensitive to a polycationic protein (protamine) are also presented. It is shown that the protamine-responsive membrane electrode appears to operate via the exact same kinetic mechanism as the heparin sensing system. SN - 0003-2700 UR - https://www.unboundmedicine.com/medline/citation/8080104/Response_mechanism_of_polymer_membrane_based_potentiometric_polyion_sensors_ L2 - https://www.lens.org/lens/search?q=citation_id:8080104 DB - PRIME DP - Unbound Medicine ER -