An Experimental Study of Membrane Materials and Inner Contacting Layers for Ion-Selective K+ Electrodes with a Stable Response and Good Dynamic Range

Agata J. Michalska, Charles Appaih-Kusi, Yook Heng Lee, Sebastian Walkiewicz, Elizabeth A H Hall

Research output: Contribution to journalArticle

79 Citations (Scopus)

Abstract

The goal was to identify formulations for use in valinomycin K+ ion-selective electrodes that could routinely achieve a detection limit of < 10-6 M, even after repeated use and exposure at higher K+ activity (0.1 M) and without the requirement for special pretreatment or conditioning in low K+ activity (10-3 M). Electrodes that would be characterized by high potential stability were sought in this work. Valinomycin-containing membranes with diffusion coefficient of ∼10 -11 cm2 s-1, formulated from methacrylic/acrylic polymers with or without plasticizer, were compared with plasticized PVC membranes (diffusion coefficient 10-8 cm2 s-1). The methacrylic/ acrylic membranes without plasticizer were shown to give an order of magnitude lower detection limit, when compared with PVC-dioctyl sebacate and o-nitrophenyl octyl ether plasticized methacrylic/acrylic polymers under the same conditions, highlighting the influence of plasticizer on the detection limit. As predicted from current theoretical derivation, the inner contacting layer in the ion-selective electrode construction was shown to be highly influential in maintaining the detection limit below 10-6 M with use and with poly(pyrrole) providing the inner contact ion-to-electron transduction function, a further order of magnitude improvement in the lower detection limit could be maintained for both chloride and hexacyanoferrate doped poly(pyrrole), when 2% ionophore was employed in the ion-selective membrane. This formulation showed extraordinary stability and reproducibility in terms of measurement range and drift over extended measurement testing, with close to Nernstian slopes. At higher ionophore concentrations (4%), the apparent selectivity of the electrode was improved at the expense of detection limit and the nature of the poly(pyrrole) dopant ion became important in determining the dominant exchange processes at the poly(pyrrole)/ion-selective membrane interface.

Original languageEnglish
Pages (from-to)2031-2039
Number of pages9
JournalAnalytical Chemistry
Volume76
Issue number7
DOIs
Publication statusPublished - 1 Apr 2004

Fingerprint

Pyrroles
Plasticizers
Ion selective membranes
Ions
Acrylics
Membranes
Valinomycin
Electrodes
Ionophores
Polyvinyl Chloride
Polymers
Ether
Chlorides
Ion exchange
Doping (additives)
Electrons
Testing
Ion-Selective Electrodes

ASJC Scopus subject areas

  • Analytical Chemistry

Cite this

An Experimental Study of Membrane Materials and Inner Contacting Layers for Ion-Selective K+ Electrodes with a Stable Response and Good Dynamic Range. / Michalska, Agata J.; Appaih-Kusi, Charles; Lee, Yook Heng; Walkiewicz, Sebastian; Hall, Elizabeth A H.

In: Analytical Chemistry, Vol. 76, No. 7, 01.04.2004, p. 2031-2039.

Research output: Contribution to journalArticle

Michalska, Agata J. ; Appaih-Kusi, Charles ; Lee, Yook Heng ; Walkiewicz, Sebastian ; Hall, Elizabeth A H. / An Experimental Study of Membrane Materials and Inner Contacting Layers for Ion-Selective K+ Electrodes with a Stable Response and Good Dynamic Range. In: Analytical Chemistry. 2004 ; Vol. 76, No. 7. pp. 2031-2039.
@article{85de2b91130644daa3446cf177d57b7f,
title = "An Experimental Study of Membrane Materials and Inner Contacting Layers for Ion-Selective K+ Electrodes with a Stable Response and Good Dynamic Range",
abstract = "The goal was to identify formulations for use in valinomycin K+ ion-selective electrodes that could routinely achieve a detection limit of < 10-6 M, even after repeated use and exposure at higher K+ activity (0.1 M) and without the requirement for special pretreatment or conditioning in low K+ activity (10-3 M). Electrodes that would be characterized by high potential stability were sought in this work. Valinomycin-containing membranes with diffusion coefficient of ∼10 -11 cm2 s-1, formulated from methacrylic/acrylic polymers with or without plasticizer, were compared with plasticized PVC membranes (diffusion coefficient 10-8 cm2 s-1). The methacrylic/ acrylic membranes without plasticizer were shown to give an order of magnitude lower detection limit, when compared with PVC-dioctyl sebacate and o-nitrophenyl octyl ether plasticized methacrylic/acrylic polymers under the same conditions, highlighting the influence of plasticizer on the detection limit. As predicted from current theoretical derivation, the inner contacting layer in the ion-selective electrode construction was shown to be highly influential in maintaining the detection limit below 10-6 M with use and with poly(pyrrole) providing the inner contact ion-to-electron transduction function, a further order of magnitude improvement in the lower detection limit could be maintained for both chloride and hexacyanoferrate doped poly(pyrrole), when 2{\%} ionophore was employed in the ion-selective membrane. This formulation showed extraordinary stability and reproducibility in terms of measurement range and drift over extended measurement testing, with close to Nernstian slopes. At higher ionophore concentrations (4{\%}), the apparent selectivity of the electrode was improved at the expense of detection limit and the nature of the poly(pyrrole) dopant ion became important in determining the dominant exchange processes at the poly(pyrrole)/ion-selective membrane interface.",
author = "Michalska, {Agata J.} and Charles Appaih-Kusi and Lee, {Yook Heng} and Sebastian Walkiewicz and Hall, {Elizabeth A H}",
year = "2004",
month = "4",
day = "1",
doi = "10.1021/ac0353132",
language = "English",
volume = "76",
pages = "2031--2039",
journal = "Analytical Chemistry",
issn = "0003-2700",
publisher = "American Chemical Society",
number = "7",

}

TY - JOUR

T1 - An Experimental Study of Membrane Materials and Inner Contacting Layers for Ion-Selective K+ Electrodes with a Stable Response and Good Dynamic Range

AU - Michalska, Agata J.

AU - Appaih-Kusi, Charles

AU - Lee, Yook Heng

AU - Walkiewicz, Sebastian

AU - Hall, Elizabeth A H

PY - 2004/4/1

Y1 - 2004/4/1

N2 - The goal was to identify formulations for use in valinomycin K+ ion-selective electrodes that could routinely achieve a detection limit of < 10-6 M, even after repeated use and exposure at higher K+ activity (0.1 M) and without the requirement for special pretreatment or conditioning in low K+ activity (10-3 M). Electrodes that would be characterized by high potential stability were sought in this work. Valinomycin-containing membranes with diffusion coefficient of ∼10 -11 cm2 s-1, formulated from methacrylic/acrylic polymers with or without plasticizer, were compared with plasticized PVC membranes (diffusion coefficient 10-8 cm2 s-1). The methacrylic/ acrylic membranes without plasticizer were shown to give an order of magnitude lower detection limit, when compared with PVC-dioctyl sebacate and o-nitrophenyl octyl ether plasticized methacrylic/acrylic polymers under the same conditions, highlighting the influence of plasticizer on the detection limit. As predicted from current theoretical derivation, the inner contacting layer in the ion-selective electrode construction was shown to be highly influential in maintaining the detection limit below 10-6 M with use and with poly(pyrrole) providing the inner contact ion-to-electron transduction function, a further order of magnitude improvement in the lower detection limit could be maintained for both chloride and hexacyanoferrate doped poly(pyrrole), when 2% ionophore was employed in the ion-selective membrane. This formulation showed extraordinary stability and reproducibility in terms of measurement range and drift over extended measurement testing, with close to Nernstian slopes. At higher ionophore concentrations (4%), the apparent selectivity of the electrode was improved at the expense of detection limit and the nature of the poly(pyrrole) dopant ion became important in determining the dominant exchange processes at the poly(pyrrole)/ion-selective membrane interface.

AB - The goal was to identify formulations for use in valinomycin K+ ion-selective electrodes that could routinely achieve a detection limit of < 10-6 M, even after repeated use and exposure at higher K+ activity (0.1 M) and without the requirement for special pretreatment or conditioning in low K+ activity (10-3 M). Electrodes that would be characterized by high potential stability were sought in this work. Valinomycin-containing membranes with diffusion coefficient of ∼10 -11 cm2 s-1, formulated from methacrylic/acrylic polymers with or without plasticizer, were compared with plasticized PVC membranes (diffusion coefficient 10-8 cm2 s-1). The methacrylic/ acrylic membranes without plasticizer were shown to give an order of magnitude lower detection limit, when compared with PVC-dioctyl sebacate and o-nitrophenyl octyl ether plasticized methacrylic/acrylic polymers under the same conditions, highlighting the influence of plasticizer on the detection limit. As predicted from current theoretical derivation, the inner contacting layer in the ion-selective electrode construction was shown to be highly influential in maintaining the detection limit below 10-6 M with use and with poly(pyrrole) providing the inner contact ion-to-electron transduction function, a further order of magnitude improvement in the lower detection limit could be maintained for both chloride and hexacyanoferrate doped poly(pyrrole), when 2% ionophore was employed in the ion-selective membrane. This formulation showed extraordinary stability and reproducibility in terms of measurement range and drift over extended measurement testing, with close to Nernstian slopes. At higher ionophore concentrations (4%), the apparent selectivity of the electrode was improved at the expense of detection limit and the nature of the poly(pyrrole) dopant ion became important in determining the dominant exchange processes at the poly(pyrrole)/ion-selective membrane interface.

UR - http://www.scopus.com/inward/record.url?scp=1842580898&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=1842580898&partnerID=8YFLogxK

U2 - 10.1021/ac0353132

DO - 10.1021/ac0353132

M3 - Article

C2 - 15053668

AN - SCOPUS:1842580898

VL - 76

SP - 2031

EP - 2039

JO - Analytical Chemistry

JF - Analytical Chemistry

SN - 0003-2700

IS - 7

ER -