Applications of ionic liquids in electrochemical sensors (original) (raw)
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Recent advances in the use of ionic liquids for electrochemical sensing
Ionic Liquids are salts that are liquid at (or just above) room temperature. They possess several advantageous properties (e.g. high intrinsic conductivity, wide electrochemical windows, low volatility, high thermal stability and good solvating ability), which make them ideal as non-volatile electrolytes in electrochemical sensors. This mini-review article describes the recent uses of ionic liquids in electrochemical sensing applications (covering the last 3 years) in the context of voltammetric sensing at solid/liquid, liquid/liquid interfaces and carbon paste electrodes, as well as their use in gas sensing, ion- selective electrodes, and for detecting biological molecules, explosives and chemical warfare agents. A comment on the future direction and challenges in this field is also presented.
Application of Room Temperature Ionic Liquids in Electrochemical Sensors and Biosensors
Ionic Liquids (ILs) are a new class of purely ionic, salt-like materials that are liquid at unusually low temperatures. The official definition of ILs uses the boiling point of water as a point of reference:“Ionic Liquids are ionic compounds which are liquid below 100 C”. In particular, salts that are liquids at room temperature are called room-temperature ionic liquids (RTILs). RTILs, also known as organic liquid, molten, or fused salts, are a class of non-molecular ionic solvents with low melting points.
2022
These days Ionic liquids (ILs) are getting more attention and catching more eyes based on numerous advantages they can offer, including low volatility, excellent thermal and chemical stability, easy handling, remarkable conductivity, and facile design. These riveting materials are formed via asymmetric cations and anions. They can mainly be found in a liquid state where temperatures are below 100 °C. Therefore, due to their unique features, they can be considered a perfect and desirable candidate in several fields, including electrochemical biosensors and detecting agents; they can play their roles as electrolytes. These unique features prompted us to present a precise and short review of the different fabrication methods of Ionic liquids. Herein, after a laconic description of ILs, a diverse range of fabrication methods was investigated, and a succinct description was given in each approach. Furthermore, where needed, some clear illustrations were used to boost apprehend. Perspectives, remarks, and challenges of different fabrication methods have been given, respectively
BioNanoScience, 2013
Nanotechnology is playing an important role in the development of biosensors. The exclusive physical and chemical properties of nanomaterials make them exceptionally suitable for designing new and improved sensing devices, especially electrochemical sensors and biosensors. Room temperature ionic liquids (RTILs) are salts that exist in the liquid phase at and around 298 K and are entirely composed of ions: a bulky, asymmetric organic cation and usually an inorganic anion but some ILs also has organic anion. ILs have received much attention as a replacement for traditional volatile organic solvents as they possess many attractive properties such as intrinsic ion conductivity, low volatility, high chemical and thermal stability, low combustibility, and wide electrochemical windows, etc. Due to negligible or nonzero volatility of these solvents, they are considered "greener" for the environment in comparison to volatile organic compounds. ILs have been widely used in electrodeposition, electrosynthesis, electrocatalysis, electrochemical capacitor, lubricants, plasticizers, solvent, lithium batteries, solvents to manufacture nanomaterials, extraction, gas absorption agents etc. [1-4]. This review discusses the electrochemical sensors and biosensors based on carbon nanotubes, metal oxide nanoparticles, and ionic liquid/composite modified electrodes. The main thrust of the review is to present an overview on the advantages of use of RTILs along with nanomaterials for electrochemical sensors and biosensors. Consequently, recent developments and major strategies for enhancing sensing performance have been thoroughly discussed.
Electroanalysis, 2008
Carbon film electrodes have been characterised in the room temperature ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethane)sulfonimide (BmimNTF 2), 1-butyl-1-methylpyrrolidinium bis(trifluoromethane)sulfonimide, (BpyrNTF 2) and 1-butyl-3-methylimidazolium nitrate (BmimNO 3), by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical behaviour of the ionic liquids depended on both cation and anion of these electrolytes. Oxygen reduction is clearly visible at carbon film electrodes-after oxygen removal the potential window was wider, that of BpyrNTF 2 being the widest. These room temperature ionic liquids were used in the electrochemical investigation of two ferrocene derivatives, benzoyl-and acetyl-ferrocene, that are both insoluble in water and cannot be investigated in aqueous solutions. They were also applied in the investigation of two sensor and biosensor mediators, copper hexacyanoferrate and poly(neutral red), with a view to using ionic liquids as electrolytes in electrochemical sensing and biosensing systems.
Ionic Liquid based polymer electrolytes for electrochemical sensors
Materials Science, 2015
Amperometric NO2 sensors with a new type of printed solid polymer electrolyte and printed carbon working electrodes were developed. The electrolytes consisted of the ionic liquids 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [EMIM][N(Tf)2], 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][CF3SO3], and 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4], which were immobilized in a poly(vinylidene fluoride) (PVDF) matrix. The analyte, gaseous nitrogen dioxide, was detected by reduction at-500 mV vs. the platinum pseudoreference electrode. The sensors showed linear behavior over the whole tested range, i.e., 0-5 ppm, and their sensitivities were in the order of hundreds of nanoamperes per one ppm of NO2. The sensor sensitivity was influenced by the electrical conductance of the electrolyte; the higher the conductance, the greater the sensor sensitivity. The rise/recovery times were of the order of tens of seconds. The use of screen printing technology for the preparation of the solid electrolyte and the carbon working electrode simplifies sensor fabrication without a negative effect on sensor performance.
Ionic liquid-based reference electrodes for miniaturized ion sensors: What can go wrong?
Sensors and Actuators B: Chemical, 2019
Ionic liquid-based reference electrodes, especially those containing 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (MeOctIm TFSI), are increasingly used in potentiometric measurements. They replace the conventional salt bridges and establish the reference potential through local partitioning of the ions of the ionic liquid between the reference membrane and the sample solution. Unless the electrochemical cell and the measurement protocol are designed appropriately, these ions can interfere with the response of ion-selective electrodes (ISEs) with polymeric membranes. This work characterizes the effect of MeOctIm TFSI on the response of K + , Na + , and Cl − ISEs with polymeric membranes. The leaching of MeOctIm TFSI from the reference membrane to the sample solution was monitored with UV-vis spectroscopy. The concentration of MeOctIm TFSI in the aqueous phase increased gradually and plateaued at approximately 1.0 mM. Concentrations as low as 100 μM of MeOctIm TFSI caused large changes to the emf (50-150 mV) of K + , Na + , and Cl − ISEs. The presence of 10 μM of TFSI − was enough to cause Donnan failure of K + ISEs with valinomycin as ionophore (that is, coextraction of K + and TFSI − into the sensing membrane). Use of less lipophilic anions such as tetrafluoroborate (BF 4-) or triflate (OTf-) postponed the onset of Donnan failure of cation-selective ISEs to higher concentrations of the anion, but decreased the stability in the reference potential and lifetime of the reference electrode. These results imply that although MeOctIm TFSI-based reference electrodes provide sample-independent and stable electrical potentials, they should be used with caution for measurements with polymeric-membrane ISEs, due to strong interference of both MeOctIm + and TFSI − with measured values of emf.
Biosensors of laccase based on hydrophobic ionic liquids derived from imidazolium cation
Journal of the Brazilian Chemical Society, 2010
Biossensores contendo lacase (Aspergillus oryzae) e líquidos iônicos derivados do cátion 1-butil-3-metilimidazol (BMI) associados com os ânions hexafluorfosfato (BMI•PF 6 ) ou bis(trifluormetilsulfonil)imida (BMI•Tf 2 N) foram construídos para determinação de adrenalina. O biossensor baseado no BMI•Tf 2 N foi selecionado por apresentar maior resposta quando comparado ao BMI•PF 6 . As melhores condições para otimização foram estabelecidas por voltametria de onda quadrada (amplitude 100 mV, frequência 10 Hz e incremento 4,0 mV). O melhor desempenho foi obtido em 50:20:15:15% (m/m/m/m) de pó de grafite:lacase:Nujol:LIs em tampão acetato 0,1 mol L -1 (pH 4,0). A curva analítica foi linear na faixa de concentração 2,49 × 10 -6 a 2,27 × 10 -4 mol L -1 com limite de detecção de 5,34 × 10 -7 mol L -1 . A recuperação de adrenalina em amostras injetáveis variou de 96,3 a 101,6%. Os resultados obtidos para a adrenalina usando o biossensor proposto e o procedimento da Farmacopéia Americana estão em concordância ao nível de confiança de 95%.
Characterisation and application of carbon film electrodes in room temperature ionic liquid media
Journal of Electroanalytical Chemistry, 2008
Carbon film electrodes have been characterised in the room temperature ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethane)sulfonimide (BmimNTF 2), 1-butyl-1-methylpyrrolidinium bis(trifluoromethane)sulfonimide, (BpyrNTF 2) and 1-butyl-3-methylimidazolium nitrate (BmimNO 3), by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical behaviour of the ionic liquids depended on both cation and anion of these electrolytes. Oxygen reduction is clearly visible at carbon film electrodes-after oxygen removal the potential window was wider, that of BpyrNTF 2 being the widest. These room temperature ionic liquids were used in the electrochemical investigation of two ferrocene derivatives, benzoyl-and acetyl-ferrocene, that are both insoluble in water and cannot be investigated in aqueous solutions. They were also applied in the investigation of two sensor and biosensor mediators, copper hexacyanoferrate and poly(neutral red), with a view to using ionic liquids as electrolytes in electrochemical sensing and biosensing systems.