Novel potentiometric and optical silver ion-selective sensors with subnanomolar detection limits

Szigeti, Zsófia; Malon, Adam; Vigassy, Tamás; Csókai, Viktor; Grűn, Alajos; Wyglądacz, Katarzyna; Yang, Nan; Xu, Chao; Chebny, Vincent J.; Bitter, István; Rathore, Rajendra; Bakker, Eric; Pretsch, Ernö

doi:10.1016/j.aca.2006.05.009

Cited by 95 publications

(54 citation statements)

References 52 publications

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“…Such methods are useful in assisting rational receptor design because the resulting data give direct feedback on the strength of the ion-receptor interaction in the final system of interest. 21 Of course, binding constants will translate into sensor selectivity. The selectivity is traditionally described by the so-called selectivity coefficient, which has its roots in the Nikolskii equation.…”

Section: Selectivitymentioning

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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Section: Selectivitymentioning

confidence: 99%

Modern directions for potentiometric sensors

Bakker¹,

Chumbimuni‐Torres²

2008

J. Braz. Chem. Soc.

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“…The Ag + -selective membrane contained 10.0 mmol kg -1 of copper (II) ionophore I and 5.0 mmol kg -1 of NaTFPB. 15 The I --ISEs contained 1.0 mmol kg -1 of MC3 and 0.75 mmol kg -1 of TDMANO 3 . Ion-selective membranes were prepared by dissolving the above-mentioned components together with PVC (33.3 wt %) and DOS (66.6 wt %) in 2 mL THF and the resulting cocktail was vortexed for 30 min.…”

Section: Membranesmentioning

confidence: 95%

Circumventing Traditional Conditioning Protocols in Polymer Membrane-Based Ion-Selective Electrodes

et al. 2016

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Preparation of ISEs often requires long and complicated conditioning protocols limiting their application as tools for in field measurements. Herein, we eliminated the need for conditioning by loading the membrane cocktail with primary ion solution. This protocol significantly shortens the preparation time of ISEs yielding functional electrodes with submicromolar detection limits.The scientific research in ion-selective electrodes (ISEs) has gained momentum within the last years due to improvements in the limits of detection and selectivity, becoming now applicable for trace-level measurements by understanding transmembrane ion fluxes. 1 The response of ISEs can be described by the phase boundary potential, E PB , according the following equation:Here a I (aq) and a I (org) are the activities of primary ion (I) of charge z in aqueous and organic phases respectively, while E 0 , R, T, and F are the standard potential, gas constant, temperature and Faraday constant, respectively. When a I (org) is kept constant, the equation 1 reduces to the well-known Nernst equation:In order to render an ion-selective membrane functional, the ionophore and lipophilic ionic sites are required. One of the major roles of ionophore is to make relatively strong complexes with the primary ion, thereby establishing their constant activity in the membrane. 2 For more details see Equations SI1-SI5 in the supporting information. The role of the lipophilic ionic sites is to provide ion-exchange properties. For cation selective membrane, this process could be described by the following equilibrium:where L is a ligand (ionophore) that forms ion-ionophore complex with ion I of stoichiometry n. + − is a lipophilic ion exchanger composed of lipophilic anion R -and its counterion M + . Partitioning of I from aqueous sample into the membrane results in its exchange with M + . Anion − remains in the membrane thereby rendering the membrane permselective while preserving the charge balance. 3 In a typical experimental protocol for the preparation of ion-selective membranes the ion-exchange process is obtained by conditioning (soaking) the membrane in an aqueous solution containing the ion I (traditional protocol). 4 Significant effort in ISEs field has been spent on researching ways to miniaturize 5-9 and optimize/simplify the preparation of ISEs. [10][11][12] Reducing or eliminating the need for the conditioning step prior to the use of the electrodes is an important step for devising a simple, practical protocol for ISEs applications. 12 This would enable nontrained personnel to use ISEs quickly and reliably. In this work we propose a simple alteration of the sensor's conditioning protocol. Instead of placing the ISEs in a solution of primary ions I, solution is added directly into the membrane cocktail prior to its casting. The concentration of that solution is calculated to allow for stoichiometric exchange of I and M. Consequently, ions I are present in the membrane facilitating the formation of ion-ionophore complex according to the ...

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“…The membranes were prepared with the newly synthesized ionophores 15-23 as described before [14]. The membrane components were dissolved in 3.0 mL of THF and shaken vigorously for at least 2 h, and then poured into a glass ring (30 mm i.d.)…”

Section: Membrane Preparationmentioning

confidence: 99%

“…Such fluxes can be reduced if primary ions in the inner filling solution are buffered with certain ligands, and thus, their concentration remains constant [27]. A number of different strategies via adjusting the concentration of inner solution have been reported [14,15,28,29]. Herein, we introduce an alternative approach using precipitation method according to the solubility product constant (K sp ) of AgCl to control the concentration of free Ag + in the inner solution.…”

Section: Characteristics Of the Ionophore-based Ag + -Isesmentioning

confidence: 99%

“…In recent years, the quest for improved lower detection limits of polymeric membrane ISEs has reinvigorated the search for better molecular receptors [2]. Several thiacrown ethers based on calixarenes have been explored as ionophores for heavy metals with lower detection limits [14,15]. However, so far there has been no report on the characterization of monoazathiacrown ethers as ionophores for the polymeric membrane ISEs with improved lower detection limits.…”

Section: Introductionmentioning

confidence: 99%

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