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Siamionau AV, Egorov VV. Determination of Single-Ion Partition Coefficients between Water and Plasticized PVC Membrane Using Equilibrium-Based Techniques. MEMBRANES 2022; 12:membranes12101019. [PMID: 36295778 PMCID: PMC9607055 DOI: 10.3390/membranes12101019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 05/10/2023]
Abstract
An experimentally simple method for the direct determination of single-ion partition coefficients between water and a PVC membrane plasticized with o-NPOE is suggested. The method uses the traditional assumption of equal single-ion partition coefficients for some reference cation and anion, in this case tetraphenylphosphonium (TPP+) and tetraphenylborate (TPB-). The method is based on an integrated approach, including direct study of some salts' distribution between water and membrane phases, estimation of ion association constants, and measurements of unbiased selectivity coefficients for ions of interest, including the reference ones. The knowledge of distribution coefficients together with ion association constants allows for direct calculation of the multiple of the single-ion partition coefficients for the corresponding cation and anion, while the knowledge of unbiased selectivity coefficients together with ion association constants allows for immediate estimation of the single-ion partition coefficients for any ion under study, if the corresponding value for the reference ion is known. Both potentiometric and extraction studies are inherently equilibrium-based techniques, while traditionally accepted methods such as voltammetry and diffusion are kinetical. The inner coherent scale of single-ion partition coefficients between water and membrane phases was constructed.
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Affiliation(s)
- Andrei V. Siamionau
- Laboratory of the Physical Chemical Investigation Methods, Research Institute for Physical Chemical Problems of the Belarusian State University, Leningradskaya Str., 14, 220006 Minsk, Belarus
- Correspondence:
| | - Vladimir V. Egorov
- Analytical Chemistry Department, Faculty of Chemistry, Belarusian State University, Leningradskaya str., 14, 220030 Minsk, Belarus
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2
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Zhang Z, Papautsky I. Solid contact ion‐selective electrodes on printed circuit board with membrane displacement. ELECTROANAL 2022. [DOI: 10.1002/elan.202100686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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3
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Zhang Z, Papautsky I. Miniature Ion‐selective Electrodes with Mesoporous Carbon Black as Solid Contact. ELECTROANAL 2021. [DOI: 10.1002/elan.202100088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Zhehao Zhang
- Department of Bioengineering University of Illinois at Chicago Chicago IL 60607 USA
- NSF Center for Advanced Design and Manufacturing of Integrated Microfluidics (CADMIM) Chicago IL 60607 USA
| | - Ian Papautsky
- Department of Bioengineering University of Illinois at Chicago Chicago IL 60607 USA
- NSF Center for Advanced Design and Manufacturing of Integrated Microfluidics (CADMIM) Chicago IL 60607 USA
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4
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Kalinichev AV, Pokhvishcheva NV, Peshkova MA. Influence of Electrolyte Coextraction on the Response of Indicator-Based Cation-Selective Optodes. ACS Sens 2020; 5:3558-3567. [PMID: 33074653 DOI: 10.1021/acssensors.0c01747] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Here, we report on systematic investigation of the impact of coextraction of the aqueous electrolyte and anion interference on the response of cation-selective bulk optodes. It is evident that to deliberately manage the properties of chemical sensors and to apply them in routine analysis, one should have exhaustive insight into their operation mechanism. Despite the extensive research in the field of ionophore-based optodes and numerous attempts for their practical application, the understanding of how coextraction of an aqueous electrolyte influences its response characteristics has not been developed thus far. Meanwhile, the electrolyte coextraction determines the detection limits of analogous ion-selective electrodes. A theoretical model based on phase distribution equilibrium is proposed to quantitatively describe the effect of Donnan exclusion failure on the response of polymeric plasticized optodes. The theoretical conclusions are confirmed by the results obtained with Na+/pH-selective optodes based on a neutral chromoionophore as a model system in solutions containing anions of various lipophilicities (Cl-, NO3-, I-, SCN-, and ClO4-). For the first time, it is shown that coextraction leads to a significant shift of the response range of the optodes as well as to nonmonotonic response curves due to the transition from cationic to anionic response. An approach to estimate the coextraction constants of electrolytes from the optode response curves is proposed. The limitations in the applicability of optodes due to co-ion interference are explored. It is found that neglecting anion interference can cause dramatic errors in the results of analyses with optical sensors.
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Affiliation(s)
- Andrey V. Kalinichev
- Chemistry Institute, Saint Petersburg State University, 26 Universitetskiy prospect, 198504 Saint Petersburg, Russia
| | - Nadezhda V. Pokhvishcheva
- Chemistry Institute, Saint Petersburg State University, 26 Universitetskiy prospect, 198504 Saint Petersburg, Russia
| | - Maria A. Peshkova
- Chemistry Institute, Saint Petersburg State University, 26 Universitetskiy prospect, 198504 Saint Petersburg, Russia
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Wang R, Du X, Wu Y, Zhai J, Xie X. Graphene Quantum Dots Integrated in Ionophore-Based Fluorescent Nanosensors for Na + and K .. ACS Sens 2018; 3:2408-2414. [PMID: 30387340 DOI: 10.1021/acssensors.8b00918] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To enrich the recipes of ion-selective nanosensors, graphene quantum dots (GQDs) were integrated into ionophore-based fluorescent nanosensors with exquisite selectivity and high sensitivity for Na+ and K+. The unique property of GQDs gave the nanosensors ultrasmall size (ca. 10 nm), high brightness, good biocompatibility, and potential pH sensing possibility. At pH 7.4, the sensors exhibited a detection range from 0.1 mM to 1 M for Na+ and from 3 μM to 1 mM for K+. The nanosensors were successfully applied to blood serum and urine samples. Chemically induced intracellular sodium concentration change in HeLa cells was also qualitatively monitored.
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Affiliation(s)
- Renjie Wang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Xinfeng Du
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Yaotian Wu
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Jingying Zhai
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
| | - Xiaojiang Xie
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
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6
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Impact of the Electrolyte Co-Extraction to the Response of the Ionophore-based Ion-Selective Electrodes. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.07.142] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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7
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Influence of Ionic Liquids on the Selectivity of Ion Exchange-Based Polymer Membrane Sensing Layers. SENSORS 2016; 16:s16071106. [PMID: 27438837 PMCID: PMC4969841 DOI: 10.3390/s16071106] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 07/08/2016] [Accepted: 07/14/2016] [Indexed: 01/26/2023]
Abstract
The applicability of ion exchange membranes is mainly defined by their permselectivity towards specific ions. For instance, the needed selectivity can be sought by modifying some of the components required for the preparation of such membranes. In this study, a new class of materials –trihexyl(tetradecyl)phosphonium based ionic liquids (ILs) were used to modify the properties of ion exchange membranes. We determined selectivity coefficients for iodide as model ion utilizing six phosphonium-based ILs and compared the selectivity with two classical plasticizers. The dielectric properties of membranes plasticized with ionic liquids and their response characteristics towards ten different anions were investigated using potentiometric and impedance measurements. In this large set of data, deviations of obtained selectivity coefficients from the well-established Hofmeister series were observed on many occasions thus indicating a multitude of applications for these ion-exchanging systems.
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Peshkova MA, Koltashova ES, Khripoun GA, Mikhelson KN. Improvement of the upper limit of the ISE Nernstian response by tuned galvanostatic polarization. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.03.139] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Xie X, Zhai J, Bakker E. Potentiometric Response from Ion-Selective Nanospheres with Voltage-Sensitive Dyes. J Am Chem Soc 2014; 136:16465-8. [DOI: 10.1021/ja5107578] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiaojiang Xie
- Department of Inorganic,
Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland
| | - Jingying Zhai
- Department of Inorganic,
Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland
| | - Eric Bakker
- Department of Inorganic,
Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland
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10
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Xie X, Mistlberger G, Bakker E. Reversible photodynamic chloride-selective sensor based on photochromic spiropyran. J Am Chem Soc 2012; 134:16929-32. [PMID: 23036043 PMCID: PMC3557920 DOI: 10.1021/ja307037z] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
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We report here for the first time on a reversible photodynamic
bulk optode sensor based on the photoswitching of a spiropyran derivative
(Sp). The photoswitching of Sp induces a large basicity increase in
the polymeric phase, which triggers the extraction of Cl– and H+. Cl– is stabilized by a lipophilic
chloride-selective ionophore inside the membrane, while H+ binds with the open form of Sp and induces a spectral change, hence
providing the sensor signal. The system was studied with spectroscopic
and electrochemical methods.
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Affiliation(s)
- Xiaojiang Xie
- Department of Inorganic and Analytical Chemistry, University of Geneva, 30 Quai Ernest Ansermet, 1211 Geneva 4, Switzerland
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11
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Silvester DS, Grygolowicz-Pawlak E, Bakker E. Potentiometric determination of coextraction constants of potassium salts in ion-selective electrodes utilizing a nitrobenzene liquid membrane phase. Anal Chim Acta 2010; 683:92-5. [PMID: 21094386 DOI: 10.1016/j.aca.2010.10.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 10/07/2010] [Accepted: 10/07/2010] [Indexed: 10/18/2022]
Abstract
A theoretical treatment of potentiometric data is applied to calculate coextraction constants (K(IA)) for three potassium salts from water into a liquid nitrobenzene phase. The experiment involves treating nitrobenzene as a membrane and contacting it with two aqueous solutions of different ion activities. In the presence of either a cation or anion exchanger, the ratio of activities of ions in the two aqueous phases gives rise to a potential difference across the membrane that depends upon the nature and charge of the counter ion of the ion-exchanger in excess. Here, the cation exchanger was chosen to be potassium tetrakis(4-chlorophenyl)borate (KTpClPB) and the anion exchanger was tetradodecylammonium chloride (TDDACl). TDDACl was incrementally added to the nitrobenzene phase containing a fixed concentration of KTpClPB, and the corresponding emf was recorded as a function of concentration of TDDACl. The membrane changes from one with cation exchanger properties (excess KTpClPB) to one with anion exchanger properties (excess TDDACl). The potential difference and shape of the titration curve can be predicted by theory based on the phase boundary potential model. Log(K(IA)) values calculated for KCl, KNO(3) and KClO(4) in nitrobenzene were found as: -10.53 (± 0.09), -8.16 (± 0.05) and -5.63 (± 0.03) respectively, in accordance with the Hofmeister series of lipophilicity, and similar to those observed in PVC membranes containing other plasticizers. The method presented here offers the advantage over other methods to calculate K(IA), in that it is relatively experimentally simple without compromising the accuracy of the calculated coextraction constants. The ability to titrate directly into the liquid membrane phase affords a higher precision compared to the preparation of a series of PVC/plasticizer membranes with different compositions.
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Affiliation(s)
- Debbie S Silvester
- Nanochemistry Research Institute, Department of Chemistry, Curtin University of Technology, GPO Box U1987, Perth 6845, Western Australia, Australia
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12
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Egorov V, Lyaskovski P, Il'inchik I, Soroka V, Nazarov V. Estimation of Ion-Pairing Constants in Plasticized Poly(vinyl chloride) Membranes Using Segmented Sandwich Membranes Technique. ELECTROANAL 2009. [DOI: 10.1002/elan.200904639] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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13
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Si P, Bakker E. Thin layer electrochemical extraction of non-redoxactive cations with an anion-exchanging conducting polymer overlaid with a selective membrane. Chem Commun (Camb) 2009:5260-2. [PMID: 19707639 DOI: 10.1039/b907893b] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report here on the selective voltammetric cation transfer into a polymeric thin layer film that is back side contacted with an anion-exchanging conducting polymer, poly(3-octylthiophene).
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Affiliation(s)
- Pengchao Si
- Nanochemistry Research Institute, Department of Applied Chemistry, Curtin University of Technology, GPO Box U1987, Perth, 6845, Western Australia, Australia
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14
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Peshkova MA, Korobeynikov AI, Mikhelson KN. Estimation of ion-site association constants in ion-selective electrode membranes by modified segmented sandwich membrane method. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2008.03.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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15
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Radu A, Meir AJ, Bakker E. Dynamic diffusion model for tracing the real-time potential response of polymeric membrane ion-selective electrodes. Anal Chem 2006; 76:6402-9. [PMID: 15516134 DOI: 10.1021/ac049348t] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A numerical solution for the prediction of the time-dependent potential response of a polymeric-based ion-selective electrode (ISE) is presented. The model addresses short- and middle-term potential drifts that are dependent on changes in concentration gradients in the aqueous sample and organic membrane phase. This work has important implications for the understanding of the real-time response behavior of potentiometric sensors with low detection limits and with nonclassical super-Nernstian response slopes. As a model system, the initial exposure of membranes containing the well-examined silver ionophore O,O' '-bis[2-(methylthio)ethyl]-tert-butylcalix[4]arene was monitored, and the large observed potential drifts were compared to theoretical predictions. The model is based on an approximate solution of the diffusion equation for both aqueous and organic diffusion layers using a numerical scheme (finite difference in time and finite elements in space). The model may be evaluated on the basis of experimentally available parameters and gives time-dependent information previously inaccessible with a simpler steady-state diffusion model. For the cases studied, the model gave a very good correlation with experimental data, albeit with lower than expected diffusion coefficients for the organic phase. This model may address numerous open questions regarding the response time and memory effects of low-detection-limit ion-selective electrodes and for other membrane electrodes where ion fluxes are relevant.
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Affiliation(s)
- Aleksandar Radu
- Departments of Chemistry and Mathematics, Auburn University, Auburn, Alabama 36849, USA
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Legin A, Makarychev-Mikhailov S, Mortensen J, Vlasov Y. Potentiometric and impedance studies of membranes based on anion-exchanger and lipophilic inert electrolyte ETH 500. Electrochim Acta 2004. [DOI: 10.1016/j.electacta.2004.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Affiliation(s)
- Eric Bakker
- Department of Chemistry, Auburn University, Auburn, Alabama 36849, USA
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Radu A, Telting-Diaz M, Bakker E. Rotating Disk Potentiometry for Inner Solution Optimization of Low-Detection-Limit Ion-Selective Electrodes. Anal Chem 2003; 75:6922-31. [PMID: 14670054 DOI: 10.1021/ac0346961] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The extent of optimization of the lower detection limit of ion-selective electrodes (ISEs) can be assessed with an elegant new method. At the detection limit (i.e., in the absence of primary ions in the sample), one can observe a reproducible change in the membrane potential upon alteration of the aqueous diffusion layer thickness. This stir effect is predicted to depend on the composition of the inner solution, which is known to influence the lower detection limit of the potentiometric sensor dramatically. For an optimized electrode, the stir effect is calculated to be exactly one-half the value of the case when substantial coextraction occurs at the inner membrane side. In contrast, there is no stir effect when substantial ion exchange occurs at the inner membrane side. Consequently, this experimental method can be used to determine how well the inner filling solution has been optimized. A rotating disk electrode was used in this study because it provides adequate control of the aqueous diffusion layer thickness. Various ion-selective membranes with a variety of inner solutions that gave different calculated concentrations of the complex at the inner membrane side were studied to evaluate this principle. They contained the well-examined silver ionophore O,O' '-bis[2-(methylthio)ethyl]-tert-butylcalix[4]arene, the potassium ionophore valinomycin, or the iodide carrier [9]mercuracarborand-3. Stir effects were determined in different background solutions and compared to theoretical expectations. Correlations were good, and the results encourage the use of such stir-effect measurements to optimize ISE compositions for real-world applications. The technique was also found to be useful in estimating the level of primary ion impurities in the sample. For an iodide-selective electrode measured in phosphoric acid, for example, apparent iodide impurity levels were calculated as 5 x 10(-10) M.
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Affiliation(s)
- Aleksandar Radu
- Department of Chemistry, Auburn University, Auburn, Alabama 36849, USA
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Malon A, Radu A, Qin W, Qin Y, Ceresa A, Maj-Zurawska M, Bakker E, Pretsch E. Improving the Detection Limit of Anion-Selective Electrodes: An Iodide-Selective Membrane with a Nanomolar Detection Limit. Anal Chem 2003; 75:3865-71. [PMID: 14572055 DOI: 10.1021/ac026454r] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The lower detection limit and the selectivity behavior of anion-selective electrodes (ISEs) are improved by using optimized inner solutions and membrane compositions. With a membrane based on the recently described ionophore [9]mercuracarborand-3, a detection limit of 2 x 10(-9) M has been achieved for iodide. Nevertheless, the improvements are less pronounced than in the case of cation ISEs. This is mainly due to the fact that so far no anion ISE is known with the extremely high selectivities of cation ISEs. If the membrane does not contain an ionophore, leaching of the ion exchanger from the membrane into the sample is also a relevant limiting factor except for ion exchangers of very high lipophilicity.
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Affiliation(s)
- Adam Malon
- Laboratorium für Organische Chemie, ETH Hönggerberg, CH-8093 Zürich, Switzerland
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Lo CK, Choi MM. Symmetrical electrochemical cell for determination of coextraction constants of metal salts for ion-selective polymeric membranes. Anal Chim Acta 2003. [DOI: 10.1016/s0003-2670(03)00420-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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21
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Peper S, Qin Y, Almond P, McKee M, Telting-Diaz M, Albrecht-Schmitt T, Bakker E. Ion-pairing ability, chemical stability, and selectivity behavior of halogenated dodecacarborane cation exchangers in neutral carrier-based ion-selective electrodes. Anal Chem 2003; 75:2131-9. [PMID: 12720352 DOI: 10.1021/ac026056o] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recently, it has been discovered that carba-closo-dodecaborates can be used as cation exchangers in neutral carrier-based ion-selective chemical sensors. Because of their inherent chemical stability and versatile functionalization chemistries, they offer many advantages that may potentially be exploited for ion analyses that require nontraditional sample conditions, including strongly acidic media. In this work, trimethylammonium salts of undecachlorinated (UCC), undecabrominated (UBC), hexabrominated (HBC), and undecaiodinated (UIC) carborane anions were prepared and evaluated for their potential use in solvent polymeric membrane-based sensors. Computational methods including Natural population analysis and electrostatic mapping were used to predict the ion-exchanging ability of each lipophilic anion. In addition, the sandwich membrane technique was used to evaluate the ion-pairing ability of each carborane anion in situ (i.e., within bis(2-ethylhexyl) sebacate (DOS)- and 2-nitrophenyl octyl ether (o-NPOE)-plasticized ISE membranes). The results of the computational and potentiometric studies found that binding affinity of the anions followed the generalized trend HBC > UCC > UBC > UIC. PVC-DOS bulk optode thin films containing the chromoionophore ETH 5315 and a respective anion were used to determine the chemical stability/lipophilicity of the carboranes and tetrakis[3,5-bis(trifluoromethyl)phenyl] borate (TFPB) in acidic media (0.2 M HOAc) under flowing conditions. The studies found that in terms of stability/lipophilicity UIC > UBC > TFPB approximately UCC >> HBC. Electrodes containing a Pb(2+)-selective ionophore, tert-butylcalix[4]arene-tetrakis(N,N-dimethylthioacetamide)(lead IV), were used to evaluate the functionality of each cation exchanger. An evaluation of response characteristics such as slope and selectivity found that UIC and UBC were quite comparable to the behavior of TFPB. Interestingly, both UIC and UBC showed a marked selectivity improvement over cadmium, with log K(pot)(pb),(Cd) values of -7.19 and -7.29, respectively, with TFPB giving a value of -5.89. Demonstrating excellent stability and suitable electrostatic properties, the carboranes, UIC in particular, are a very promising alternative to the tetraphenylborates and should find widespread application in the field of chemical sensors.
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Affiliation(s)
- Shane Peper
- Department of Chemistry, Auburn University, Alabama 36849, USA
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