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Morawska K, Wardak C. Application of ionic liquids in ion-selective electrodes and reference electrodes: A review. Chemphyschem 2024; 25:e202300818. [PMID: 38252078 DOI: 10.1002/cphc.202300818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 12/21/2023] [Accepted: 01/19/2024] [Indexed: 01/23/2024]
Abstract
Ionic liquids (ILs) are organic chemical compounds that are composed only of ions, a large organic cation and a smaller inorganic or organic anion. These are salts whose melting point is lower than the boiling point of water. ILs have many interesting properties, thanks to which they find great practical applications in analytics, electrochemistry, separation techniques, catalysis and others. One of the many areas of application of ionic liquids is sensors especially electrochemical sensors including ion-selective electrodes. In this case, the properties of ILs that are particularly useful include very good electrical conductivity, high electrochemical stability, good extraction properties, hydrophobic character and compatibility with other materials, e. g. polyvinyl chloride plasticizers or carbon nanomaterials. ILs were used as components of ion-selective membranes, both polymeric ones based on PVC and membranes in carbon paste electrodes. ILs performed various functions in these membranes, including lipophilic ionic additive, ionophore/ion exchanger, plasticizer, transducer media and matrix. They were also used as a component of the intermediate layer in solid contact ISEs. The last chapter presents examples of the use of ILs in reference electrodes. This review discusses the use of ionic liquids in ion-selective electrodes (ISEs) and reference electrodes over the last ten years.
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Affiliation(s)
- Klaudia Morawska
- Department of Analytical Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 3, 20-031, Lublin, Poland
| | - Cecylia Wardak
- Department of Analytical Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 3, 20-031, Lublin, Poland
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2
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Egorov VV, Siamionau AV, Ragoyja EG. H +-Selective Electrodes Based on Amine-Type Ionophores: Generalized Theory and A Priori Quantification of Lower and Upper Detection Limits. ACS Sens 2023; 8:2087-2095. [PMID: 37097260 DOI: 10.1021/acssensors.3c00417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
A critical analysis of the known theories of functioning of H+-selective electrodes (H+-SEs) based on neutral amine-type carriers is given. A model of specific ion association is proposed, according to which, in membranes plasticized with 2-nitrophenyloctyl ether, the protonated ionophore and cation-exchanger form much stronger ion pairs with inorganic ions extracted from the sample solution than with each other, and simple equations that describe the lower and upper limit detection (pHUDL and pHLDL) are obtained. A feasible and reliable method for quantifying the pKa values of ionophores in the membrane phase from potentiometric data is substantiated. The efficiency of using single-ion partition coefficients and ion pair formation constants for a priori quantitative description of the H+-SE response in solutions of various compositions has been demonstrated for the first time. It is shown that the width of the dynamic response range of such electrodes depends on the nature of the tertiary amino group, and the reasons for the observed effect are discussed.
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Affiliation(s)
- Vladimir V Egorov
- Belarusian State University, 4, Nezavisimosti Avenue, 220030 Minsk, Belarus
| | - Andrei V Siamionau
- Research Institute for Physical Chemical Problems of the Belarusian State University, Leningradskaya str., 14, 220030 Minsk, Belarus
| | - Ekaterina G Ragoyja
- Belarusian State University, 4, Nezavisimosti Avenue, 220030 Minsk, Belarus
- Research Institute for Physical Chemical Problems of the Belarusian State University, Leningradskaya str., 14, 220030 Minsk, Belarus
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3
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Dong XIN, Spindler BD, Kim M, Stein A, Bühlmann P. Spontaneous Mesoporosity-Driven Sequestration of Ionic Liquids from Silicone-Based Reference Electrode Membranes. ACS Sens 2023; 8:1774-1781. [PMID: 37043696 DOI: 10.1021/acssensors.3c00085] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
Nanopore-driven sequestration of ionic liquids from a silicone membrane is presented, a phenomenon that has not been reported previously. Reference electrodes with ionic liquid doped polydimethylsiloxane (PDMS) reference membranes and colloid-imprinted mesoporous carbon (CIM) as solid contact are not functional unless special attention is paid to the porosity of the solid contact. In the fabrication of such reference electrodes, a solution of a hydroxyl-terminated silicone oligomer, ionic liquid, cross-linking reagent, and polymerization catalyst is deposited on top of the carbon layer, rapidly filling the pores of the CIM carbon. The catalyzed polymerization curing of the silicone quickly results in cross-linking of the hydroxyl-terminated polydimethylsiloxane oligomers, forming structures that are too large to penetrate the CIM carbon pores. Therefore, as solvent evaporation from the top of freshly prepared membranes drives the diffusional transport of solvent toward that membrane surface, the solvent molecules that leave the CIM carbon pores can only be replaced by the ionic liquid. This depletes the ionic liquid in the reference membrane that overlies the CIM carbon solid contact and increases the membrane resistance by up to 3 orders of magnitude, rendering the devices dysfunctional. This problem can be avoided by presaturating the CIM carbon with ionic liquid prior to the deposition of the solution that contains the silicone oligomers and ionic liquid. Alternatively, a high amount of ionic liquid can be added into the membrane solution to account for the size-selective sequestration of ionic liquid into the carbon pores. Either way, a wide variety of ionic liquids can be used to prepare PDMS-based reference electrodes with CIM carbon as a solid contact. A similar depletion of the K+ ionophore BME-44 from ion-selective silicone membranes was observed too, highlighting that the depletion of active ingredients from polymeric ion-selective and reference membranes due to interactions with high surface area solid contacts may be a more common phenomenon that so far has been overlooked.
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Affiliation(s)
- Xin I N Dong
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Brian D Spindler
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Minog Kim
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Andreas Stein
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Philippe Bühlmann
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
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Tian W, Cao H, Zhang Y, Na Z, Hui Y, Jin Z, Lang MF, Li Y, Sun J. Novel Flexible Ag/AgCl Quasi-Reference Electrode with Fishbone Nanowire Structure for Remarkable Potential Stability, Long-Term Reliability, and Noninvasive Electrocardiography. Anal Chem 2023; 95:2413-2419. [PMID: 36633558 DOI: 10.1021/acs.analchem.2c04499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The roadblocks for the planar silver/silver chloride (Ag/AgCl) quasi-reference electrode (qRE) development are the potential stability and long-term reliability as potentiometric sensors. Although there is a significant amount of work on potentiometric screen-printed and inkjet-printed sensors, none of the REs has comparable performance to that of the conventional glass RE and knowledge on reliable planar Ag/AgCl qREs is still limited. Here, a novel fishbone-structured flexible Ag/AgCl qRE (Fishbone-Ag/AgCl qRE) was developed and its stability and long-term reliability were significantly improved. The stability of the Fishbone-Ag/AgCl qRE was comparable to that of a commercial glass Ag/AgCl RE. In a long-term stability test, the Fishbone-Ag/AgCl qRE could continuously and stably operate for more than 4 h. Shelf-life testing revealed a 6 month life span. The conductivity and diameter of the nanowires in the fishbone structure of the Ag/AgCl qRE had important influences on electrochemical properties. The conductivity of the qRE influenced the charge-transfer rate in the electrode so that it affected the potential stability. Thicker diameter and slight chlorination on the surface of the AgNWs resulted in enhanced long-term reliability of the qRE. The capabilities of this new nanostructured material were applied in vivo for noninvasive monitoring of electrocardiogram. The discovery is elementary and substantially informs improved nanostructure RE design for testing and commercial medical device applications.
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Affiliation(s)
- Wenshuai Tian
- College of Chemical and Environmental Engineering, Institute of Microanalysis, Dalian University, Dalian, Liaoning 116622, China
| | - Houyong Cao
- College of Chemical and Environmental Engineering, Institute of Microanalysis, Dalian University, Dalian, Liaoning 116622, China
| | - Yu Zhang
- College of Chemical and Environmental Engineering, Institute of Microanalysis, Dalian University, Dalian, Liaoning 116622, China
| | - Zhaolin Na
- College of Chemical and Environmental Engineering, Institute of Microanalysis, Dalian University, Dalian, Liaoning 116622, China
| | - Yu Hui
- College of Chemical and Environmental Engineering, Institute of Microanalysis, Dalian University, Dalian, Liaoning 116622, China
| | - Zhengmu Jin
- Dalian Ofei Electronics CO.,LTD., Dalian 116021, China
| | - Ming-Fei Lang
- Medical College, Institute of Microanalysis, Dalian University, Dalian, Liaoning 116622, China.,Dalian Key Laboratory of Oligosaccharide Recombination and Recombinant Protein Modification, Dalian University, Dalian, Liaoning 116622, China
| | - Yanzhao Li
- Affiliated Zhongshan Hospital of Dalian University, Dalian 116001, China
| | - Jing Sun
- College of Chemical and Environmental Engineering, Institute of Microanalysis, Dalian University, Dalian, Liaoning 116622, China.,Dalian Key Laboratory of Oligosaccharide Recombination and Recombinant Protein Modification, Dalian University, Dalian, Liaoning 116622, China
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5
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Kalinichev AV, Pokhvishcheva NV, Peshkova MA. Response Mechanism of Polymeric Liquid Junction-Free Reference Electrodes Based on Organic Electrolytes. MEMBRANES 2023; 13:118. [PMID: 36676925 PMCID: PMC9864460 DOI: 10.3390/membranes13010118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 06/17/2023]
Abstract
To achieve a transition from conventional liquid-junction reference electrodes (LJF REs) to their all-solid-state alternatives, organic electrolytes are often introduced into the polymeric electrode membranes. In this article, we implement a theoretical approach to the explanation and quantification of the boundary potential stabilization phenomenon for the electrodes modified with organic electrolytes (Q+B-). For the first time, stabilization of the phase boundary potential due to the partition of lipophilic ions of the Q+B- electrolyte between the polymeric and aqueous phases is numerically simulated to predict the LJF electrodes behavior. The impact of the hydrophilic electrolyte on the potential stabilization is demonstrated both numerically and experimentally. The developed model predicted that the small additions of a traditional ion-exchanger enhance performance of the Q+B--based reference electrodes. For some specific cases, the optimal concentrations of Q+B- and ion-exchanger in the polymeric phase are suggested to provide stable electrode potential in a broad range of aqueous electrolyte concentrations. In addition, the efficiency of the stabilization was shown to be dependent on the overall Q+B- load in the polymeric membrane rather than on the closeness of the partition coefficients of the Q+ and B- ions; and on the volume of the aqueous phase. The model results are verified experimentally with poly(vinyl chloride) membranes containing ion-exchanger or hydrophilic electrolyte and Q+B- in various proportions. A good agreement between the measured electrode response and the theoretical results is observed in a broad range of solution concentrations. In particular, the cationic function of membranes containing KTpClPB is suppressed, and the electrodes begin to behave as REs starting from 50-60 mol. % of ETH500 electrolyte added to the membrane, relative to the total amount of salt.
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Gan S, Liao C, Liang R, Du S, Zhong L, Tang Y, Han T, Bao Y, Sun Z, Ma Y, Niu L. A Solid-Contact Reference Electrode Based on Silver/Silver Organic Insoluble Salt for Potentiometric Ion Sensing. ACS MEASUREMENT SCIENCE AU 2022; 2:568-575. [PMID: 36785773 PMCID: PMC9886000 DOI: 10.1021/acsmeasuresciau.2c00036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/31/2022] [Accepted: 08/01/2022] [Indexed: 06/18/2023]
Abstract
Solid-contact ion-selective electrodes are a type of ion measurement devices that have been focused in wearable biotechnology based on the features of miniaturization and integration. However, the solid-contact reference electrodes (SC-REs) remain relatively less focused compared with numerous working (or indicator) electrodes. Most SC-REs in wearable sensors rely on Ag/AgCl reference electrodes with solid electrolytes, for example, the hydrophilic electrolyte salts in polymer matrix, but face the risk of electrolyte leakage. Herein, we report a type of SC-REs based on the silver/silver tetraphenylborate (Ag/AgTPB) organic insoluble electrode. The SC-RE consists of a Ag substrate, a solid contact (AgTPB), and a plasticized poly(vinyl chloride) (PVC) membrane containing the hydrophobic organic salt of tetrabutylammonium tetraphenylborate (TBATPB). The potentiometric measurements demonstrated that the SC-RE of Ag/AgTPB/PVC-TBATPB showed a reproducible standard potential in various electrolytes and disclosed high long-term stability. This SC-RE was further fabricated on a flexible substrate and integrated into all-solid-state wearable potentiometric ion sensor for sweat Cl- monitoring.
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Affiliation(s)
- Shiyu Gan
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Chunxian Liao
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Rongfeng Liang
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Sanyang Du
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Lijie Zhong
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Yitian Tang
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Tingting Han
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Yu Bao
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Zhonghui Sun
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Yingming Ma
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
| | - Li Niu
- Guangzhou
Key Laboratory of Sensing Materials & Devices, Center for Advanced
Analytical Science, School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China
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7
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Micro- and nano-devices for electrochemical sensing. Mikrochim Acta 2022; 189:459. [DOI: 10.1007/s00604-022-05548-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 11/02/2022] [Indexed: 11/24/2022]
Abstract
AbstractElectrode miniaturization has profoundly revolutionized the field of electrochemical sensing, opening up unprecedented opportunities for probing biological events with a high spatial and temporal resolution, integrating electrochemical systems with microfluidics, and designing arrays for multiplexed sensing. Several technological issues posed by the desire for downsizing have been addressed so far, leading to micrometric and nanometric sensing systems with different degrees of maturity. However, there is still an endless margin for researchers to improve current strategies and cope with demanding sensing fields, such as lab-on-a-chip devices and multi-array sensors, brain chemistry, and cell monitoring. In this review, we present current trends in the design of micro-/nano-electrochemical sensors and cutting-edge applications reported in the last 10 years. Micro- and nanosensors are divided into four categories depending on the transduction mechanism, e.g., amperometric, impedimetric, potentiometric, and transistor-based, to best guide the reader through the different detection strategies and highlight major advancements as well as still unaddressed demands in electrochemical sensing.
Graphical Abstract
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8
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Increasing the Lifespan of Reference Electrodes by Increasing the Diffusion Length. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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Nigde M, Agir I, Yıldırım R, Isildak I. Development and comparison of various rod-shaped mini-reference electrode compositions based on Ag/AgCl for potentiometric applications. Analyst 2022; 147:516-526. [PMID: 35044380 DOI: 10.1039/d1an01754c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Several fundamentally similar, miniaturized solid-state reference electrode designs, and their fabrication and comparison are described in this article. All electrodes were based on Ag/AgCl as their reference element. The best electrode (a three-layer assembly with graphite oxide, epoxy, and hardener as the framework providers and with well-mixed micro-Ag particles in the bottom layer, AgCl in the middle layer, and fine KCl powder in the top layer) exhibited satisfactory short-term performance to replace a commercial reference electrode in many cases and was rigorously tested in terms of pH response, long-term leakage, and the effect of oxygen to better evaluate its characteristics. To assess the electrode's performance in medically important studies, cytotoxicity experiments and tests in artificial saliva were also conducted. All tests demonstrated that our best reference electrode was stable and had a long shelf life.
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Affiliation(s)
- Mustafa Nigde
- Faculty of Chemical and Metallurgical Engineering, Department of Bioengineering, Yildiz Technical University, 34220, Istanbul, Turkey.
| | - Ismail Agir
- Faculty of Engineering and Natural Sciences, Department of Bioengineering, Istanbul Medeniyet University, 34720, Istanbul, Turkey
| | - Rıdvan Yıldırım
- Faculty of Chemical and Metallurgical Engineering, Department of Bioengineering, Yildiz Technical University, 34220, Istanbul, Turkey.
| | - Ibrahim Isildak
- Faculty of Chemical and Metallurgical Engineering, Department of Bioengineering, Yildiz Technical University, 34220, Istanbul, Turkey.
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Chronopotentiometric Evaluation of Ionization Degree and Dissociation Constant of Imidazolium-Based Ionic Liquid [C6Meim][NTf2] in Polymeric Plasticized Membranes. MEMBRANES 2022; 12:membranes12020130. [PMID: 35207052 PMCID: PMC8877390 DOI: 10.3390/membranes12020130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 11/17/2022]
Abstract
Ionic liquids (ILs) have a wide variety of applications in modern electrochemistry due to their unique electrolytic properties. In particular, they are promising candidates as dopants for polymeric membranes in potentiometric sensors and liquid-junction free reference electrodes. However, the effective use of ILs requires a comprehensive understanding of their electrolytic behavior in the polymeric phase. We report here the exploration of the electrolytic and diffusion properties of IL 1-hexyl-3-methyl-1H-imidazol-3-ium bis[(trifluoromethyl)sulfonyl]amide ([C6Meim][NTf2]) in a poly(vinyl chloride) matrix. Chronopotentiometry is utilized to determine the concentration of charge carriers, ionic diffusion coefficients and apparent dissociation constant of [C6Meim][NTf2] in PVC membranes plasticized with a mixture of [C6Meim][NTf2] and bis(2-ethylhexyl) sebacate (DOS) over a wide range of IL concentrations. The diffusion properties of [C6Meim][NTf2] are confirmed by NMR-diffusometry. The non-monotonic electrolytic behavior of the IL in PVC-DOS matrix is described for the first time. A maximum ionization degree and diffusion coefficient is observed at 30 wt.% of IL in the plasticizing mixture. Thus, it is shown that by varying the flexible parameter of the IL to plasticizer ratio in the polymeric phase one can tune the electrolytic and transport properties of sensing PVC membranes.
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Kakiuchi T, Kawamoto T, Yamazaki T, Yamamoto M. Potentiometric properties of the electrochemical cells equipped with ionic liquid salt bridge and its application to determine the solubility of the ionic liquid and the mean activity coefficients of the chloride salt of the ionic liquid-constituent cation in water. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2022.116036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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12
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Dialysis membranes as liquid junction materials: Simplified model based on the phase boundary potential. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2021.115886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lisak G. Reliable environmental trace heavy metal analysis with potentiometric ion sensors - reality or a distant dream. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 289:117882. [PMID: 34364114 DOI: 10.1016/j.envpol.2021.117882] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 07/13/2021] [Accepted: 07/29/2021] [Indexed: 06/13/2023]
Abstract
Over two decades have passed since polymeric membrane ion-selective electrodes were found to exhibit sufficiently lower detection limits. This in turn brought a great promise to measure trace level concentrations of heavy metals using potentiometric ion sensors at environmental conditions. Despite great efforts, trace analysis of heavy metals using ion-selective electrodes at environmental conditions is still not commercially available. This work will predominantly concentrate on summarizing and evaluating prospects of using potentiometric ion sensors in view of environmental determination of heavy metals in on-site and on-line analysis modes. Challenges associated with development of reliable potentiometric sensors to be operational in environmental conditions will be discussed and reasoning behind unsuccessful efforts to develop potentiometric on-site and on-line environmental ion sensors will be explored. In short, it is now clear that solely lowering the detection limit of the ion-selective electrodes does not guarantee development of successful sensors that would meet the requirement of environmental matrices over long term usage. More pressing challenges of the properties and the performance of the potentiometric sensors must be addressed first before considering extending their sensitivity to low analyte concentrations. These are, in order of importance, selectivity of the ion-selective membrane to main ion followed by the membrane resistance to parallel processes, such as water ingress to the ISM, light sensitivity, change in temperature, presence of gasses in solution and pH and finally resistance of the ion-selective membrane to fouling. In the future, targeted on-site and on-line environmental sensors should be developed, addressing specific environmental conditions. Thus, ion-selective electrodes should be developed with the intention to be suitable to the operational environmental conditions, rather than looking at universal sensor design validated in the idealized and simple sample matrices.
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Affiliation(s)
- Grzegorz Lisak
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore; Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, Singapore, 637141, Singapore.
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Electrochemical sensor for tricyclic antidepressants with low nanomolar detection limit: Quantitative Determination of Amitriptyline and Nortriptyline in blood. Talanta 2021; 239:123072. [PMID: 34864535 DOI: 10.1016/j.talanta.2021.123072] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 11/08/2021] [Accepted: 11/14/2021] [Indexed: 11/24/2022]
Abstract
Amitriptyline and its metabolite, Nortriptyline are commonly used tricyclic antidepressant (TCA) drugs that are electrochemically active. In this work, the performance characteristics of a plasticized PVC membrane-coated glassy carbon (GC) electrode are described for the voltammetric quantification of Amitriptyline and Nortriptyline in whole blood. The highly lipophilic Amitriptyline and Nortriptyline preferentially partition into the plasticized PVC membrane where the free drug is oxidized on the GC electrode. The concentrations of the drugs in the membrane are orders of magnitude larger than in the sample solution, resulting in superb limit of detection (LOD) of the membrane-coated voltammetric sensor: 3 nmol/L for Amitriptyline and 20 nmol/L for Nortriptyline. Conversely, hydrophilic components of the sample solution, e.g., proteins, the protein-bound fraction of the drugs, and electrochemically active small molecules are blocked from entering the membrane, which provides exceptional selectivity for the membrane-coated sensor and feasibility for the measurements of Amitriptyline in whole blood. In this work, the concentrations of Amitriptyline and Nortriptyline were determined in whole blood using the sensor and the results of our analysis were compared to the results of the standard HPLC-MS method. Based on our experience, the one-step voltammetric methods with the membrane-coated sensor may become a real alternative to the significantly more complex HPLC-MS analysis.
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Abstract
Fluctuations of pH in coastal systems are generally surveyed through potentiometric pH measurements. A new concept of a unified pH scale was introduced with the great advantage of enabling comparability of absolute values, pHabs, pertaining to any medium. Using water as an anchor solvent, yielding pHabsH2O, enables referencing the pHabs values to the conventional aqueous pH scale. The current work aims at contributing to implement pHabsH2O to saline solutions. To this purpose, differential potentiometric measurements, with a salt bridge of ionic liquid [N2225][NTf2], were carried out aiming at overcoming problems related to residual liquid junction potentials that affect the quality of such measurements. The ability to measure pHabsH2O with acceptable uncertainty was evaluated using Tris-Tris·HCl standard buffer solutions prepared in a background matrix close to the characteristics of estuarine systems (salinity of 20) as well as with NaCl solutions with ionic strength between 0.005 and 0.8 mol kg−1. The present study shows that for high ionic strength solutions, such as seawater, challenges remain when addressing the assessment and quantification of ocean acidification in relation to climate change. Improvements are envisaged from the eventual selection of a more adequate ionic liquid.
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Bartoszewicz B, Lewenstam A, Migdalski J. Solid-Contact Electrode with Composite PVC-Based 3D-Printed Membrane. Optimization of Fabrication and Performance. SENSORS 2021; 21:s21144909. [PMID: 34300652 PMCID: PMC8309799 DOI: 10.3390/s21144909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 11/16/2022]
Abstract
Intense interest in reference electrode design and fabrication has recently been enriched with the application of 3D printing of electrodes with salt-loaded PVC membranes. This type of material is attractive in sensor technology and is challenging to implement in 3D. In this report, several improvements and simplifications in the technology were focused on and supported by a fundamental electrochemical characterization.
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Rousseau CR, Bühlmann P. Calibration-free potentiometric sensing with solid-contact ion-selective electrodes. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2021.116277] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Cheong YH, Ge L, Lisak G. Highly reproducible solid contact ion selective electrodes: Emerging opportunities for potentiometry - A review. Anal Chim Acta 2021; 1162:338304. [PMID: 33926699 DOI: 10.1016/j.aca.2021.338304] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 01/20/2021] [Accepted: 02/04/2021] [Indexed: 02/07/2023]
Abstract
The solid contact ion-selective electrodes (SC-ISEs) have been extensively studied in the field of ion sensing as they offer the possibility of miniaturization, are relatively inexpensive in comparison to other analytical techniques and allow straightforward and routine analyses of ions in a number of clinical, environmental and industrial process samples. In recent years, significant interest has grown in the development of SC-ISEs with well-defined interfacialpotentials at the membrane, solid contact, and substrate electrode interfaces. This has resulted in interesting SC-ISEs exhibiting high electrode-to-electrode potential reproducibility, for those made in a single batch of electrodes, some approaching or exceeding those observed in liquid-contact ISEs. The advancement in the potential reproducibility of SC-ISEs has been partially achieved by scrutinizing insufficiently reproducible fabrication methods of SC-ISEs, or by introducing novel control measures or modifiers to components of the ISEs. This paper provides an overview of the methods as well as the challenges in establishing and maintaining reproducible potentials during the fabrication and use of novel SC-ISEs. The rules outlined in the works reviewed may form the basis of further development of cost-effective, user-friendly, limited calibration or calibration-free potentiometric SC-ISEs to achieve reliable ion analyses here and now.
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Affiliation(s)
- Yi Heng Cheong
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore; Robert Bosch (South East Asia) Pte Ltd, 11 Bishan Street 21, Singapore, 573943, Singapore; Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore, 637141, Singapore
| | - Liya Ge
- Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore, 637141, Singapore
| | - Grzegorz Lisak
- School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore; Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, Singapore, 637141, Singapore.
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19
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Affiliation(s)
- Elena Zdrachek
- Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland
| | - Eric Bakker
- Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland
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20
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Single-ion activity: a nonthermodynamically measurable quantity. J Solid State Electrochem 2020. [DOI: 10.1007/s10008-020-04758-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Chen XV, Stein A, Bühlmann P. Reference Electrodes Based on Ionic Liquid-Doped Reference Membranes with Biocompatible Silicone Matrixes. ACS Sens 2020; 5:1717-1725. [PMID: 32366104 DOI: 10.1021/acssensors.0c00363] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Many reference electrodes with an ionic liquid-doped reference membrane contain a plasticizer that can gradually leach out into the sample. However, because many common plasticizers are known to be endocrine disruptors and may induce inflammatory reactions, they are preferably avoided for wearable or implantable sensors. Therefore, this work tested polymeric reference electrode membranes prepared by solvent casting from seven commercially available biocompatible silicones that are widely used in implantable devices. Only reference electrodes with membranes consisting of poly(3,3,3-trifluoropropylmethylsiloxane) (Fluorosilicone 1) and one of several 1-methyl-3-alkylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids provided a stable and sample-independent potential in electrolyte solutions spanning the range of electrolyte concentrations in human blood, with more hydrophobic ionic liquids performing better. Over 8 days at 37 °C in artificial blood electrolyte solutions, the reference membranes doped with 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide exhibited a potential drift as low as 20 μV/h. In 10% animal serum, a 112 μV/h drift was observed over 5.8 days. The other six silicone materials doped with an ionic liquid either failed to form self-standing membranes or did not provide a sample-independent potential in the ionic concentration range tested. In case of the functional reference electrodes, differential scanning calorimetry confirmed good miscibility between the ionic liquid and the polymer matrix, whereas the poor miscibility of four polymer matrixes and the ionic liquids-as confirmed by differential scanning calorimetry-correlated with an undesirable sample dependence of the reference potential.
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Affiliation(s)
- Xin V. Chen
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Andreas Stein
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Philippe Bühlmann
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
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22
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Anderson EL, Chopade SA, Spindler B, Stein A, Lodge TP, Hillmyer MA, Bühlmann P. Solid-Contact Ion-Selective and Reference Electrodes Covalently Attached to Functionalized Poly(ethylene terephthalate). Anal Chem 2020; 92:7621-7629. [PMID: 32351106 DOI: 10.1021/acs.analchem.0c00296] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Numerous ion-selective and reference electrodes have been developed over the years. Following the need for point-of-care and wearable sensors, designs have transitioned recently from bulky devices with an aqueous inner filling solution to planarizable solid-contact electrodes. However, unless the polymeric sensing and reference membranes are held in place mechanically, delamination of these membranes from the underlying solid to which they adhere physically limits sensor lifetime. Even minor external mechanical stress or thermal expansion can result in membrane delamination and, thereby, device failure. To address this problem, we designed a sensing platform based on poly(ethylene terephthalate) substrates to which polyacrylate-based sensing and polymethacrylate-based reference membranes are attached covalently. Ion-selective membranes with covalently attached or freely dissolved ionophore- and ionic-liquid-doped reference membranes can be directly photopolymerized onto surface-functionalized poly(ethylene terephthalate), resulting in the formation of covalent bonds between the underlying substrate and the attached membranes. H+- and K+-selective electrodes thus prepared exhibit highly selective responses with the theoretically expected (Nernstian) response slope, and reference electrodes provide sample-independent reference potentials over a wide range of electrolyte concentrations. Even repeated mechanical stress does not result in the delamination of the sensing and reference membranes, leading to electrodes with much improved long-term performance. As demonstrated for poly(ethylene-co-cyclohexane-1,4-dimethanol terephthalate) (PETG), this approach may be expanded to a wide range of other polyester, polyamide, and polyurethane platform materials. Covalent attachment of sensing and reference membranes to an inert plastic platform material is a very promising approach to a problem that has plagued the field of ion-selective electrodes and field effect transistors for over 30 years.
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23
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Sassa F, Biswas GC, Suzuki H. Microfabricated electrochemical sensing devices. LAB ON A CHIP 2020; 20:1358-1389. [PMID: 32129358 DOI: 10.1039/c9lc01112a] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Electrochemistry provides possibilities to realize smart microdevices of the next generation with high functionalities. Electrodes, which constitute major components of electrochemical devices, can be formed by various microfabrication techniques, and integration of the same (or different) components for that purpose is not difficult. Merging this technique with microfluidics can further expand the areas of application of the resultant devices. To augment the development of next generation devices, it will be beneficial to review recent technological trends in this field and clarify the directions required for moving forward. Even when limiting the discussion to electrochemical microdevices, a variety of useful techniques should be considered. Therefore, in this review, we attempted to provide an overview of all relevant techniques in this context in the hope that it can provide useful comprehensive information.
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Affiliation(s)
- Fumihiro Sassa
- Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
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25
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Anderson EL, Troudt BK, Bühlmann P. Critical Comparison of Reference Electrodes with Salt Bridges Contained in Nanoporous Glass with 5, 20, 50, and 100 nm Diameter Pores. ANAL SCI 2020; 36:187-191. [PMID: 31495816 DOI: 10.2116/analsci.19p235] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Porous glass frits are frequently used to contain the salt bridges through which reference electrodes interface samples. Prior work with widely used glass frits with 4 - 10 nm diameter pores showed that, when samples have a low electrolyte strength, electrostatic screening of sample ions by charged sites on the glass surface occurs. This creates an ion-specific phase-boundary potential at the interface between the sample and frit, and it biases the potential of the reference half-cell. Use of frits with much larger pores eliminates this problem but results in the need for frequent replenishing of the bridge electrolyte. A methodical study to determine the optimum pore size has been missing. We show here that charge screening of sample ions occurs when the pore size of nanoporous glass frits is on the order of 1 - 50 nm and samples have a low electrolyte strength. An increase in pores size to 100 nm eliminates charge screening in samples with ionic strengths in the 1.0 M to 3.3 × 10-4 M range. However, the rates of electrolyte solution flow through frits with 1, 5, 20, 50, and 100 nm pores are still low, which makes diffusion the dominant mode of ion transport into and out of these frits. Consequently, the flow of bridge electrolyte into samples is not fast enough to prevent diffusion of ions and electrically neutral components from the sample diffusing into the salt bridge, which can result in cross contamination among samples.
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26
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Gao W, Zdrachek E, Xie X, Bakker E. A Solid‐State Reference Electrode Based on a Self‐Referencing Pulstrode. Angew Chem Int Ed Engl 2020; 59:2294-2298. [DOI: 10.1002/anie.201912651] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Wenyue Gao
- Department of Inorganic and Analytical ChemistryUniversity of Geneva Quai Ernest-Ansermet 30 CH-1211 Geneva Switzerland
- Department of ChemistrySouthern University of Science and Technology Shenzhen 518055 China
| | - Elena Zdrachek
- Department of Inorganic and Analytical ChemistryUniversity of Geneva Quai Ernest-Ansermet 30 CH-1211 Geneva Switzerland
| | - Xiaojiang Xie
- Department of ChemistrySouthern University of Science and Technology Shenzhen 518055 China
| | - Eric Bakker
- Department of Inorganic and Analytical ChemistryUniversity of Geneva Quai Ernest-Ansermet 30 CH-1211 Geneva Switzerland
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27
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Affiliation(s)
- Elena Zdrachek
- Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland
| | - Eric Bakker
- Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland
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28
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Shao Y, Ying Y, Ping J. Recent advances in solid-contact ion-selective electrodes: functional materials, transduction mechanisms, and development trends. Chem Soc Rev 2020; 49:4405-4465. [DOI: 10.1039/c9cs00587k] [Citation(s) in RCA: 143] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This article presents a comprehensive overview of recent progress in the design and applications of solid-contact ion-selective electrodes (SC-ISEs).
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Affiliation(s)
- Yuzhou Shao
- Laboratory of Agricultural Information Intelligent Sensing
- School of Biosystems Engineering and Food Science
- Zhejiang University
- Hangzhou
- China
| | - Yibin Ying
- Laboratory of Agricultural Information Intelligent Sensing
- School of Biosystems Engineering and Food Science
- Zhejiang University
- Hangzhou
- China
| | - Jianfeng Ping
- Laboratory of Agricultural Information Intelligent Sensing
- School of Biosystems Engineering and Food Science
- Zhejiang University
- Hangzhou
- China
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29
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Gao W, Zdrachek E, Xie X, Bakker E. A Solid‐State Reference Electrode Based on a Self‐Referencing Pulstrode. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201912651] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Wenyue Gao
- Department of Inorganic and Analytical ChemistryUniversity of Geneva Quai Ernest-Ansermet 30 CH-1211 Geneva Switzerland
- Department of ChemistrySouthern University of Science and Technology Shenzhen 518055 China
| | - Elena Zdrachek
- Department of Inorganic and Analytical ChemistryUniversity of Geneva Quai Ernest-Ansermet 30 CH-1211 Geneva Switzerland
| | - Xiaojiang Xie
- Department of ChemistrySouthern University of Science and Technology Shenzhen 518055 China
| | - Eric Bakker
- Department of Inorganic and Analytical ChemistryUniversity of Geneva Quai Ernest-Ansermet 30 CH-1211 Geneva Switzerland
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30
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Galiullin TM, Pokhvishcheva NV, Kalinichev AV, Peshkova MA. Evaluation of Ionic Liquids Based on Amino Acid Anions for Use in Liquid‐junction Free Reference Electrodes. ELECTROANAL 2019. [DOI: 10.1002/elan.201900125] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Timur M. Galiullin
- Chemistry InstituteSaint Petersburg State University 26 Universitetskiy prospect 198504 Saint Petersburg Russia
| | - Nadezhda V. Pokhvishcheva
- Chemistry InstituteSaint Petersburg State University 26 Universitetskiy prospect 198504 Saint Petersburg Russia
| | - Andrey V. Kalinichev
- Chemistry InstituteSaint Petersburg State University 26 Universitetskiy prospect 198504 Saint Petersburg Russia
| | - Maria A. Peshkova
- Chemistry InstituteSaint Petersburg State University 26 Universitetskiy prospect 198504 Saint Petersburg Russia
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