Studies on the phase boundaries and the significance of ionic sites of liquid membrane ion‐selective electrodes

Bühlmann, Philippe; Yajima, Seishi; Tohda, Koji; Umezawa, Keitaro; Nishizawa, Seiichi; Umezawa, Yoshio

doi:10.1002/elan.1140070905

Cited by 90 publications

(74 citation statements)

References 19 publications

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“…Because of the expected build-up of a concentration gradient, the concentration at the membrane surface would be >5·10 À9 mol L À1 Pb 2+ . This process is in complete analogy with the primary ion release of a K + -selective LC-ISE with NaCl as internal solution, where the released K + also originated solely from the membrane [45]. According to these considerations, improvements in the lower detection limits are to be expected by reducing the dimensions of the solidcontact ISE.…”

Section: Resultsmentioning

confidence: 99%

A polypyrrole-based solid-contact Pb2+-selective PVC-membrane electrode with a nanomolar detection limit

et al. 2004

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Ion-selective electrodes (ISE) based on conventional plasticized PVC membranes with solid inner contact (SC) have so far had unsatisfactory lower detection limits. Here it is shown that electropolymerization of pyrrole in the presence of potassium hexacyanoferrate(II)/(III) on Pt results in adequate inner contact for SC-ISE. The nanomolar lower detection limit achieved with the Pb 2+ -selective PVC membranes investigated is comparable with values obtained with optimized internal solutions of liquid-contact ISE.

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Section: Resultsmentioning

confidence: 99%

A polypyrrole-based solid-contact Pb2+-selective PVC-membrane electrode with a nanomolar detection limit

et al. 2004

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“…13 Indeed, later experiments with purified membranes containing the well established receptor Valinomycin confirmed the expected breakdown of the desired sensing characteristics. 14 …”

Section: General Principlesmentioning

confidence: 99%

Modern directions for potentiometric sensors

Bakker¹,

Chumbimuni‐Torres²

2008

J. Braz. Chem. Soc.

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Este artigo apresenta uma revisão dos mais recentes progressos dos eletrodos íons-seletivos de membrana polimérica. É discutida uma essência curta da teoria básica, enfatizando como a força eletromotriz pode ser usada para calcular as constantes de ligação do ionóforo, e como a seletividade e o limite de detecção estão relacionados aos processos de membrana mais importantes. Os recentes progressos na diminuição dos limites de detecção dos ISEs são descritos, incluindo recentes tentativas no desenvolvimento de ISEs de contato sólido, e inovações na detecção de quantidades ultra-pequenas de íons em baixas concentrações. Esses progressos têm alçado o caminho para usar sensores potenciométricos em bioanálise com afinidade ultra-sensível junto com nanopartículas usadas como marcadores. Os resultados recentes estabelecem que a potenciometria compara-se favoravelmente com a análise de redissolução eletroquímica. Outros novos progressos com os eletrodos de íon-seletivo são também descritos, incluindo o conceito de potenciometria de calibração interna, coulometria de corrente controlada, cronopotenciometria pulsada, e titulação rápida localizada com membranas íon-seletivas para desenhar sensores de detecção direta da acidez total sem perturbação da amostra. Estes progressos têm aberto um amplo campo para novos desenvolvimentos e aplicações nesta área. This paper gives an overview of the newest developments of polymeric membrane ion-selective electrodes. A short essence of the underlying theory is given, emphasizing how the electromotive force may be used to assess binding constants of the ionophore, and how the selectivity and detection limit are related to the basic membrane processes. The recent developments in lowering the detection limits of ISEs are described, including recent approaches of developing all solid state ISEs, and breakthroughs in detecting ultra-small quantities of ions at low concentrations. These developments have paved the way to use potentiometric sensors as in ultra-sensitive affinity bioanalysis in conjunction with nanoparticle labels. Recent results establish that potentiometry compares favorably to electrochemical stripping analysis. Other new developments with ion-selective electrodes are also described, including the concept of backside calibration potentiometry, controlled current coulometry, pulsed chronopotentiometry, and localized flash titration with ion-selective membranes to design sensors for the direct detection of total acidity without net sample perturbation. These developments have further opened the field for exciting new possibilities and applications.

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“…Such anionic excluders are beneficial to both neutral and charged carrier-based sensors [23,24]. In the case of sensors based on neutral ionophores, these ionic sites with a charge sign opposite to that of the primary ion are necessary for the sensor to give the Nernstian response [25][26][27][28]. Also, these lipophilic excluders help to reduce the membrane resistance [29], improve the selectivity [30][31][32] and reduce interference from sample anions [33,34].…”

Section: Effect Of Plasticizers and Ionophore Compositionsmentioning

confidence: 99%

A PVC plasticized membrane sensor for nickel ions

et al. 2006

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Abstract.A new PVC membrane sensor, which is highly selective towards Ni (II) ions, has been developed using a thiophene-derivative Schiff base as the ionophore. The best performance was exhibited by the membrane having the composition percentage ratio of 5:3:61:31 (ionophore:NaTPB:DBP:PVC) (w=w), where NaTPB is the anion excluder, sodium tetraphenylborate and DBP is the plasticizing agent (dibutyl phthalate). The membrane exhibited a good Nernstian response for nickel ions over the concentration range of 1.0Â10 À1 -5.0Â10 À6 M (limit of detection is 1.8Â10 À6 M) with a slope of 29.5 AE 1.0 mV per decade of activity. It has a fast response time of <20 s and can be used for a period of 4 months with good reproducibility. The sensor is suitable for use in aqueous solutions of a wide pH range of 3.2-7.9. The sensor shows high selectivity to nickel ions over a large number of mono-, bi-and trivalent cations. It has been successfully used as an indicator electrode in the potentiometric titration of nickel ions against EDTA and also for direct determination of nickel content in real samples -wastewater samples from electroplating industries and Indian chocolates.

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Studies on the phase boundaries and the significance of ionic sites of liquid membrane ion‐selective electrodes

Cited by 90 publications

References 19 publications

A polypyrrole-based solid-contact Pb2+-selective PVC-membrane electrode with a nanomolar detection limit

A polypyrrole-based solid-contact Pb2+-selective PVC-membrane electrode with a nanomolar detection limit

Modern directions for potentiometric sensors

A PVC plasticized membrane sensor for nickel ions

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