EIS study of potentiometric membranes selective to Ca2+ employing the new ionophoric antibiotic tetronasin (original) (raw)
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A new calcium-sensor based on ion-selective conductometric microsensors - membranes and features
Analytical and Bioanalytical Chemistry, 2001
Based on the concept of ion-selective conductometric microsensors (ISCOM) a new calcium sensor was developed and characterized. ISCOM have a single probe, all-solid-state construction and do not need a reference electrode. These sensors are amenable to miniaturization and integration in the true sense of integrated circuit and microsystem technologies. The detection is accomplished by measurement of the bulk conductance G m of a thin polymeric membrane containing an ion-complexing agent, where the magnitude of G m can be related to the content of the primary ion in the analyzed solution. Thin-film platinum electrodes forming an interdigitated electrode are used as the transducer to detect the conductivity of the polymeric membrane. Optimization of the membrane composition was carried out by testing different types of calcium-ionophores, polymers, and plasticizers. The sensor characteristics have been investigated. The limit of detection is about 10-7 mol L-1. The dynamic range is 10-6-10-1 mol L-1 with a response time of less than 5 s. These parameters are comparable to those of corresponding potentiometric calcium selective electrodes (ISE). The Ca 2+-ISCOM demonstrates good practical relevant selectivities against typical interfering ions for biomedical and environmental applications.
International Journal of Chemistry and Technology, 2018
This work deals with the development of micro-size potentiometric calcium-selective electrode. A simple and rapid potentiometric method of determining calcium concentration, based on 10,19-Bis[(octadecylcarbamoyl) methoxyacetyl]- 1,4,7,13,16–pentaoxa-10,19-diazacycloheneicosane, is described. For this aim, calcium-selective polyvinylchloride (PVC) membrane was prepared by coating on the surface of solid-contact. Calcium-selective PVC membrane electrode does not contain internal reference electrode and solution. The potentiometric performance of calcium-selective PVC membrane electrode (selectivity constant, liner working range, detection limit, response time, pH working range, repeatability, lifetime, and time dependent potential decay) was determined using computer controlled measurement system in static conditions. The results showed that the calcium-selective electrode exhibited good reproducibility in calcium determination.
Analytical Chemistry, 2004
An all-solid-state calcium-selective electrode was constructed with poly(pyrrole) solid-contact doped with calcium complexing ligand Tiron. The potentiometric response of this sensor can have a linear range down to 10-9 M with a slope close to Nernstian and detection limit equal to 10-9.6. The effects of pH and the activity of the interfering ion in the conditioning solution on the potentiometric behavior of the constructed sensors were examined. Potential stability, reproducibility, and impedance studies were performed. The selectivity of the constructed electrode is better than that of the conventional calcium-selective electrode with internal filling solution of 10-2 M CaCl 2 and comparable to that of the best liquid-contact electrodes.
The fabrication of potentiometric membrane sensors and their applications
2010
Abstract Ionophore-incorporated PVC-membrane sensors are well-established analytical tools routinely used for the selective and direct measurement of a wide variety of different ions in complex biological and environmental samples. The key ingredient of such plasticized PVC-members is the involved ionophore, defining the selectivity of the electrodes complex formation with the cation of interest. In the past few years, the development of new ion-selective electrodes for various ions has been reported in
Method of Achieving Desired Potentiometric Responses of Polyacrylate-Based Ion-Selective Membranes
Analytical Chemistry, 2008
We introduce a simple procedure allowing preparation of cation-selective electrodes with poly(n-butyl acrylate)based membranes containing different proportions of primary and interfering ions introduced already at the membrane preparation step, by using two different liphophilic salts of the same anion. With this approach the time required to achieve saturation of polyacrylate membranes with primary ions can be significantly shortened. Moreover, depending on the ratio of the primary and interfering ions introduced to the membrane cocktail, different potentiometric responses are obtained ranging from typical (with micromolar detection limit), through lower detection limits to super-Nernstian ones.
Physicochemical Problems of Mineral Processing, 2019
The potential creating properties of a group of acidic chelating compounds are presented. The studies have been carried out by the constructing of new ion-selective electrodes based on PVC membranes doped with the studied compounds, and determining the basic analytical parameters of the electrodes. The usefulness of eight out of nine investigated compounds in the preparation of the membrane phase electrodes selective for cobalt, zinc and cadmium has been shown. It has been also found that the acidic properties of ionophore have an essential influence on the analytical parameters of the constructed electrodes. The response mechanism of the obtained electrodes has been investigated by simultaneous spectrophotometric-potentiometric measurement of membranes used in electrodes. It has been found that during the conditioning of electrode, a complex of active substance with primary ion is formed in the membrane phase, then the membrane composition is established and remains unchanged in the next measurements.
Ionophores in polymeric membranes for selective ion recognition; impedance studies
Electrochimica Acta, 2006
Synthetic calix arene-crown ionophores for selective Na + (ionophore L1) and Cs + -ions (ionophore L2) recognition find application in ion-selective membrane electrodes (ISE) for analytical purpose. Selectivity coefficients for the electrodes with compounds L1 and L2 are log K pot Na,Cs = −2.6 and log K pot Cs,Na = −2.4, respectively. Electrodes of two different construction: all-solid-state (ASS) (with conducting polymer layer on glassy carbon or platinum as ion-to-electron transducer) and conventional ion-selective electrode (ISE) (with liquid electrolyte and Ag/AgCl) are presented and their properties and lifetime are being compared. Resistance of PVC membrane with ionophores L1 and L2 were within the range 0.15-1.4 M depending on the type of the outer electrolyte and its concentration. Conductivity of the membranes was in the range 0.7 × 10 −8 to 6 × 10 −8 −1 cm −1 . Warburg coefficients σ were within 0.16 × 10 4 to 12.7 × 10 4 s −1/2 , dielectric constant values ε were in a range 28-60 depending mainly on the type of plasticizer.
Analytical and Bioanalytical Chemistry, 2006
In this work, ion-selective electrodes for calcium ion were investigated. Two ionophores were used in the membranes: ETH 1001 and ETH 129. An internal filling solution buffered for primary ion was used that allowed the lower detection limit to be decreased down to 10 −8.8 M. Theoretical and experimental electrode characteristics pertaining to both primary and interfering ions are discussed. Better behavior was obtained with the electrode prepared with ETH 129 in the membrane. This electrode would be the most likely candidate for obtaining a low Ca 2+ detection limit in measurements performed with high K + , Na + , Mg 2+ background, which is found inside the cells of living organisms, for example. The potentiometric response of the electrode in solutions containing main and interfering ions is in good agreement with simulated curves obtained using the Nernst-Planck-Poisson (NPP) model.
Analytica Chimica Acta, 2007
The ion selective electrode (ISE)-based potentiometric approach is shown to be an effective means of characterizing the anion recognition sites in the molecular receptor calix[2]pyridino[2]pyrrole (CPP). In particular, potentiometric pH-measurements involving the use of experimental PVCmembranes based on CPP revealed the existence of both mono-and diprotonated forms of the receptor under readily accessible conditions. Based on these analyses, apparent surface protonation constants for this heterocalixarene were found to lie between 8.5-8.9 (pK B1 ) and 3.3-3.8 (pK B2 ). CPP was found to interact with targeted anionic analytes based on both coulombic and hydrogen bond interactions, as inferred from varying the kinds of ionic sites present within the membrane phase. Potentiometric selectivity studies revealed that CPP preferred "Y-shaped" anions (e.g. acetate, lactate, benzoate) over spherical anions (e.g. fluoride and chloride), fluoride over chloride within the set of spherical anions, and the ortho-isomer over the corresponding meta-and para-isomers in the case of hydroxybenzoate (salicylate and congeners). In the context of this study the advantages of potentiometric determinations of acetylsalicylic acid using optimized PVC-membranes based on CPP relative to more conventional PVC-membrane ISEs based on traditional anion exchanger were also demonstrated.