The mechanism of transfer of K+ between aqueous solutions and PVC membranes containing valinomycin

Armstrong, R.D.; Lockhart, J. C.; Todd, M.

doi:10.1016/0013-4686(86)85038-1

Cited by 52 publications

(24 citation statements)

References 2 publications

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“…Warburg impedance was reported before for PVC membranes, only if the concentration of carrier and mobile site species were approximately equal to each other [24,25]. …”

Section: Resultsmentioning

confidence: 99%

Manganese(III) Porphyrin-based Potentiometric Sensors for Diclofenac Assay in Pharmaceutical Preparations

Vlascici

Pruneanu

Olenic

et al. 2010

Sensors

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Two manganese(III) porphyrins: manganese(III) tetraphenylporphyrin chloride and manganese(III)-tetrakis(3-hydroxyphenyl)porphyrin chloride were tested as ionophores for the construction of new diclofenac–selective electrodes. The electroactive material was incorporated either in PVC or a sol–gel matrix. The effect of different plasticizers and additives (anionic and cationic) on the potentiometric response was studied. The best results were obtained for the PVC membrane plasticized with dioctylphtalate and having sodium tetraphenylborate as a lipophilic anionic additive incorporated. The sensor response was linear in the concentration range 3 × 10−6 – 1 × 10−2 M with a slope of −59.7 mV/dec diclofenac, a detection limit of 1.5 × 10−6 M and very good selectivity coefficients. It was used for the determination of diclofenac in pharmaceutical preparations, by direct potentiometry. The results were compared with those obtained by the HPLC reference method and a good agreement was found between the two methods.

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“…Warburg impedance was reported before for PVC membranes, only if the concentration of carrier and mobile site species were approximately equal to each other [24,25]. …”

Section: Resultsmentioning

confidence: 99%

Manganese(III) Porphyrin-based Potentiometric Sensors for Diclofenac Assay in Pharmaceutical Preparations

Vlascici

Pruneanu

Olenic

et al. 2010

Sensors

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“…Finally, when the valinomycin/KBU 4 ratio is equal to 1, the complexation was probably not complete, which decreased the ML þ concentration and then increased the resistance of the membrane abnormally. Armstrong et al [19,20] have already noted that 1 is a critical value for the val/KBU 4 ratio for which the dissociation of the (Kval) þ complex occurs prior to transfer. Fig.…”

Section: Influence Of the Valinomycin/kbu 4 Ratiomentioning

confidence: 96%

“…Therefore, in this situation, the limiting step was ionic transfer at the interface, which would suppose that the valinomycin complex was not entirely formed under these experimental conditions, as complexation should enhance ionic transfer. Armstrong et al [19,20] have already noted that a ratio nearly greater than 1 is necessary to obtain good working conditions for the membrane. In the derivation of the model, it was shown that C Lt ¼ C Ym À 1 b is a critical concentration for the system.…”

Section: Influence Of the Valinomycin/kbu 4 Ratiomentioning

confidence: 96%

Investigation of ion-selective electrodes with neutral ionophores and ionic sites by EIS. II. Application to K+ detection

Gabrielli

Hémery

Letellier

et al. 2004

Journal of Electroanalytical Chemistry

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“…Investigations by EIS on valinomycin-based K þ -selective solvent polymeric membranes without added ionic sites [2] revealed that a resistive surface layer may build up between the membrane and the aqueous sample solution, thus contributing to a significant surface resistance [3]. In similar experiments but using membranes with added potassium tetraphenylborate (KTPB) as ion exchanger sites, Armstrong et al observed the low frequency semicircle only with the discriminated ion (Na þ ) but not with the primary one (K þ ) [5]. Later, with Ca 2þ -ISEs based on ETH 1001 or ETH 129 in 2-nitrophenyl octyl ether (o-NPOE)/PVC membranes, a significant surface resistance was obtained only when the molar ionophore concentration relative to KTPB was not high enough to fully complex the cations in the membrane [6].…”

Section: Introductionmentioning

confidence: 98%

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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The mechanism of transfer of K+ between aqueous solutions and PVC membranes containing valinomycin

Cited by 52 publications

References 2 publications

Manganese(III) Porphyrin-based Potentiometric Sensors for Diclofenac Assay in Pharmaceutical Preparations

Manganese(III) Porphyrin-based Potentiometric Sensors for Diclofenac Assay in Pharmaceutical Preparations

Investigation of ion-selective electrodes with neutral ionophores and ionic sites by EIS. II. Application to K+ detection

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

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