Partial blocking of ion transport at the interface of an ion-selective liquid membrane electrode by neutral surfactants

Ye, Qingshan; Vincze, Árpád; Horvai, George; Leermakers, F.A.M.

doi:10.1016/s0013-4686(98)00160-1

Cited by 13 publications

(16 citation statements)

References 19 publications

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“…Since the conditioning of the membranes also has an influence on their resistance, it was concluded that the resistive surface layer is formed when the membranes are brought into contact with an aqueous sample [3]. As it was suspected that surfactants used in PVC manufacturing might be responsible for the resistive surface layer, Horvai et al [9] systematically investigated a series of uncharged sugar alkyl ester surfactants in valinomycin-based bis(2-ethylhexyl) sebacate (DOS)/PVC membranes without added ionic sites. The impedance spectra recorded in 10 À3 M NaCl (Na þ being a discriminated ion) on both sides of the membrane showed a significant low-frequency semicircle when using sorbitan monostearate (SMS, see Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The impedance spectra recorded in 10 À3 M NaCl (Na þ being a discriminated ion) on both sides of the membrane showed a significant low-frequency semicircle when using sorbitan monostearate (SMS, see Fig. 1) and a small one with sorbitan monopalmitate (SMP); however, such a semicircle was neither observed with about 100 times less lipophilic sorbitan monolaurate nor with the more rigid sorbitan monooleate [9]. Based on these results and on model calculations, the authors concluded that a self-assembly process leads to a compact surface layer of high resistance (e.g., ca.…”

Section: Introductionmentioning

confidence: 99%

“…Based on these results and on model calculations, the authors concluded that a self-assembly process leads to a compact surface layer of high resistance (e.g., ca. 2.5 MW for the two surfaces with SMS) if the membrane contains a sufficiently lipophilic surfactant with flexible alkyl chains [9].…”

Section: Introductionmentioning

confidence: 99%

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Surface Resistance and Potentiometric Response of Polymeric Membranes Doped with Nonionic Surfactants

Muslinkina

Pretsch

2004

Electroanalysis

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The influence of lipophilic, electrically neutral surfactants added to the membrane on the ion transfer resistance between an aqueous sample and a polymeric ion-selective membrane has been studied by electric impedance spectroscopy and potentiometry. An increase in the surface resistance and a shift of the apparently super-Nernstian response to lower sample ion activities has been observed when using the nonpolar bis(2-ethylhexyl) sebacate as plasticizer.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surface Resistance and Potentiometric Response of Polymeric Membranes Doped with Nonionic Surfactants

Muslinkina

Pretsch

2004

Electroanalysis

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“…Malinowska et al [77,78] found that this type of surfactants can introduce a significant positive signal bias (> 100 mV) to iMg sensors (using ETH 7025 as the ionophore), an effect not observed for iCa sensors and a dramatic loss of selectivity for Mg which renders direct iMg measurement virtually impossible. The mechanism may be due to the formation of a thin surfactant film on the sensor surface that alters the electrode partitioning and ion-exchange pattern [79]. This surfactant mechanism may also play a role in the observed interference by silicone on AVL iMg sensors discussed in Section 3.2 Accordingly, IFCC's guidelines for measuring iMg in blood [68], recommend avoiding polyethylene oxide based materials in calibrants or QC standards.…”

Section: Other Factors Affecting Img Sensorsmentioning

confidence: 99%

Point Of Care Testing of Ionized Magnesium in Blood with Potentiometric Sensors - Opportunities and Challenges

Zhang

2011

Am. J. Biomed. Sci.

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Magnesium assays are being increasingly requested in hospitals and clinical research institutions. The ionized form of magnesium (iMg) is regarded as the biologically active fraction. Ionophore-based potentiometric sensors can determine iMg and apply a selectivity correction for co-existing interfering electrolytes, e.g. Ca 2+ . This technology has been used in several commercial blood analyzers for measuring iMg in whole blood samples. This report reviews the utility of iMg in clinical settings with emphasis on point of care (POC) application, potentiometric Mg 2+ sensor technology and challenges and opportunities for future ionized magnesium assays.

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“…Similar to natural ion channel proteins, the marker species in these cases are not redox active, but sample ions for which the membrane is selective 10, 11…”

Section: Introductionmentioning

confidence: 99%

Ion Channel Mimetic Chronopotentiometric Polymeric Membrane Ion Sensor for Surface-Confined Protein Detection

Xu¹,

Bakker

2008

Langmuir

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The operation of ion channel sensors is mimicked with functionalized polymeric membrane electrodes, using a surface confined affinity reaction to impede the electrochemically imposed ion transfer kinetics of a marker ion. A membrane surface biotinylated by covalent attachment to the polymeric backbone is used here to bind to the protein avidin as a model system. The results indicate that the protein accumulates on the ion-selective membrane surface, partially blocking the current induced ion transfer across the membrane/aqueous sample interface, and subsequently decreases the potential jump in the so-called super-Nernstian step that is characteristic of a surface depletion of the marker ion. The findings suggest that such a potential drop could be utilized to measure the concentration of protein in the sample. Because the sensitivity of protein sensing is dependent on the effective blocking of the active surface area, it can be improved with a hydrophilic nanopore membrane applied on top of the biotinylated ion-selective membrane surface. Based on cyclic voltammetry characterization, the nanoporous membrane electrodes can indeed be understood as a recessed nanoelectrode array. The results show that the measuring range for protein sensing on nanopore electrodes is shifted to lower concentrations by more than one order of magnitude, which is explained with the reduction of surface area by the nanopore membrane and the related more effective hemispherical diffusion pattern.

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Partial blocking of ion transport at the interface of an ion-selective liquid membrane electrode by neutral surfactants

Cited by 13 publications

References 19 publications

Surface Resistance and Potentiometric Response of Polymeric Membranes Doped with Nonionic Surfactants

Surface Resistance and Potentiometric Response of Polymeric Membranes Doped with Nonionic Surfactants

Point Of Care Testing of Ionized Magnesium in Blood with Potentiometric Sensors - Opportunities and Challenges

Ion Channel Mimetic Chronopotentiometric Polymeric Membrane Ion Sensor for Surface-Confined Protein Detection

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