Liquid Membrane Electrode Research Articles

Fast chromium determination in pharmaceutical tablets by using electrochemical sensors: Preparation and comparison

In the present paper, three electrodes were prepared with the aim of detecting chromium (III) in pharmaceutical tablets and comparing their capabilities and efficiency. At first, N-(pyridine-2-ylcarbamothioyl) benzamide (NP2YCTB) was synthesized and characterized by 1H NMR, FTIR, and 13C NMR spectroscopy methods. Then, it is used as a sensing material to prepare three types of chromium potentiometry sensors including solid-state electrodes (SSE), coated wire electrodes (CWE) as asymmetric electrodes, and liquid membrane electrodes (LME) as symmetric electrodes. The responses of all electrodes were Nernstian. Field-emission scanning electron microscopy was utilized to investigate the liquid membrane morphology. The presence of chromium (III) in the membrane was proved using Energy-dispersive X-ray spectroscopy and the coordination of NP2YCTB heteroatoms with chromium (III) was confirmed by Fourier transform infrared spectroscopy. The limit of detection for SSE (3 × 10−9 mol/L) was enhanced compared with LME (7 × 10−6 mol/L) and CWE (3 × 10−7 mol/L). The response time of electrodes was very short so it was about 5–6 s for LME and CWE and 5–8 s for SSE. The sensors were used for the potentiometric determination of chromium (III) in pharmaceutical tablets and in the potentiometric titration of it with EDTA.

Reference Electrodes with Polymer-Based Membranes-Comprehensive Performance Characteristics.

Several types of liquid membrane and solid-state reference electrodes based on different plastics were fabricated. In the membranes studied, equitransferent organic (QB) and inorganic salts (KCl) are dispersed in polyvinyl chloride (PVC), polyurethane (PU), urea-formaldehyde resin (UF), polyvinyl acetate (PVA), as well as remelted KCl in order to show the matrix impact on the reference membranes’ behavior. The comparison of potentiometic performance was made using specially designed standardized testing protocols. A problem in the reference electrode research and literature has been a lack of standardized testing, which leads to difficulties in comparing different types, qualities, and properties of reference electrodes. Herein, several protocols were developed to test the electrodes’ performance with respect to stability over time, pH sensitivity, ionic strength, and various ionic species. All of the prepared reference electrodes performed well in at least some respect and would be suitable for certain applications as described in the text. Most of the reference types, however, demonstrated some weakness that had not been previously highlighted in the literature, due in large part to the lack of exhaustive and/or consistent testing protocols.

Multimetallic Electrocatalyst Stabilized by Atomic Ordering

The absence of low-platinum, high-activity, and satisfied-durability electrocatalysts for oxygen reduction reaction has bottlenecked the wide adoption of proton exchange membrane fuel cells for decades. In this issue of Joule, Sun and coworkers introduce a class of atomic-ordering L10 CoPt electrocatalyst for oxygen reduction catalysis, which exceeds the DOE 2020 technique target in both liquid half-cell and membrane electrode assembly conditions, representing a promising strategy to overcome this long-standing barrier.

Preparation and Application of Tetracycline Hydrochloride Liquid membrane Electrodes.

Two liquid membrane electrodes for (TCH) were prepared by using ion pair which included phosphomolybdic acid (PMA)-(TCH) with plasticizers: Di-n-butyl phthalate(DBPH), and di-octylphenylphosphonate (DOPH). Tetracycline electrodes were gave a Nernstain response equal to 56. 51 and 50. 66 mV/decade for membranes depended on DBPH and DOPH as a plastisizers, respectively. Linear ranges were around 6. 8×10-6- 1. 0×10-1 and 1. 0×10-5-1. 0×10-1 M, respectively. Detection limit were equal to 4. 0×10-6, 5. 0×10-6 M, respectively. PH range were also studied at three different concentration of tetracycline solutions. As well as were studied lifetime, selectivity, potentiometric methods such as direct, standard addition , multiple standard addition and titration methods were applied to determination tetracycline in pharmaceutical preparation

Studying the Effect of Membrane Thickness on the Performance of Green ISE-Potentiometric Sensors: Application to Ritodrine HCl and Its Active Impurity, Tyramine

Factors affecting the performance of polyvinyl chloride (PVC) based ISE were recently the scope of study by several researchers; however, no enough data has related to the thickness of the PVC membrane to performance characteristics and sensitivity of sensors. The current work introduces an ecofriendly experimental approach to evaluate the effect of membrane composition including ion exchanger and plasticizer along with thickness on the performance of a PVC sensor for determination of a tocolytic selective ß2-agonist; ritodrine HCl (RTH), in presence of its active impurity, tyramine. Thirteen different PVC membranes were prepared by varying the content of ion exchanger types and amounts constructing different thickness to address their effect on their performance characteristics. A comparative study was held among the fabricated sensors for determination of RTH in pharmaceutical dosage form, and biological fluids including human plasma and urine. It was found that the thickness of liquid membrane electrodes had a remarkable effect on the sensitivity of PVC based ion-selective electrode. The proposed sensors proved acceptable selectivity for RTH against tyramine and common inorganic species. The proposed technique presents a green alternative to reported ones by saving cost, time and effort, and yielding of the minimum amount of wastes.

Rapid Monitoring of Copper Over a Wide Concentration range by High-Sensitive Potentiometric Membrane Electrode Based on 1-cyano-1-piperidino-2(N- piperidino methyl)-cyclo hexane

n this paper, 1-cyano-1-piperidino-2(N- piperidino meth-yl)-cyclohexane was synthesized. The lowest-energy conformer of this molecule (Ligand) with axial and equatorial forms of cyanide toward cyclohexane and local minima corresponding to their complexes with various ions were obtained using Monte Carlo procedure by Molecular Mechanics with MMFF94 method. The calculated results of the Gibbs free energy of the reaction using density functional theory (DFT) show that the thermodynamic reactivity of complexation of copper ion with studied ligand is the best. Finally, a selective and sensitive copper-ion selective liquid membrane electrode for potentiometric monitoring of ultra-trace amounts of Cu2+ was prepared by using 1-cyano-1-piperid-ino-2(N- piperidino methyl)-cyclohexane as an excellent ionophore. This electrode exhibits a Nernstian response for Cu2+ ions over a con-centration range (1.5 × 10-2 to 1.0 × 10-8 mol L-1) with a slope of 28.4±0.4 mV per decade. The limit of detection of the sensor is 6.3 × 10-9 mol L-1. The sensor has a relatively fast response time (<10 s) and a useful working pH range of 5.0–8.5. Interference of some cations was also evaluated. The practical utility of the Cu2+ ion sensor has been demonstrated by using it as an indicator electrode in potentiomet-ric titration of Cu2+ with EDTA and for direct determination of Cu2+ in well water samples.

Sensor-array-based evaluation and grading of beef taste quality

A sensor array composed of ion electrodes including 2 glass electrodes, 3 liquid-membrane electrodes and 7 insoluble salt electrodes was built. Before detection, the working electrodes were activated as required in activate fluids, and the stability states of sensors were analyzed in deionized water. Beef samples were evaluated after all working electrodes stabilized. The response signals from the samples were recorded by an electrochemical workstation and used as the evaluation results. A beef taste sensory evaluation criterion was built and used into sensory evaluation of beef samples. The samples were scored with quality grades according to this criterion, and the results were compared with the results of the sensor array in evaluation of beef broth samples. The evaluation results were processed by principal component analysis and used to build a beef taste quality evaluation model based on artificial neural networks. Tests show this model has an accuracy of 90% in classification of beef taste quality grades.

Submicromolar determination of praepagen HY surfactant using new liquid inner contact electrodes

New liquid membrane electrodes for submicromolar determination of praepagen HYCl surfactant have been prepared. These electrodes utilize HYCl with phosphotungstic acid (PTA) as ion-pair (HY–PT) dissolved in the plasticizers: dibutyl phthalate (DBP) encoded sensor S1, dioctyl phthalate (DOP) encoded sensor S2, dioctylsebacate (DOS) encoded sensor S3 and tris(2-ethylhexyl) phosphate (TOPh) encoded sensor S4. The proposed electrodes exhibit Nernstian slopes of 59.5±0.6, 58.5±0.6, 55.2±0.6 and 57.3±0.5mV/decade in the concentration ranges 1.0×10−7–1.0×10−2, 2.5×10−8–1.0×10−2, 8.0×10−8–1.0×10−2 and 1.0×10−7–1.0×10−2M and notably low limits of detection: 1.0×10−7, 2.0×10−8, 3.5×10−8 and 8.5×10−8M for sensors S1, S2, S3 and S4 respectively. The sensors have considerably short response times (5–10s) and good repeatability within the pH range 2.8–9.4. The electrodes exhibit excellent selectivity for HY+ ions over many inorganic and organic cations. These electrodes are useful for determination of HYCl in shampoo and liquid detergent solutions as proved by standard addition and the calibration curve methods. Furthermore, the successful use as indicator electrode was culminated by the potentiometric titration of HY+ ions in water samples.

Preparation of a ticlopidine potentiometric sensor and its application to pharmaceutical and biological analysis

Ticlopidine (Tic) ion selective liquid membrane electrode was constructed from poly (vinyl chloride) containing Tic-tetraphenylborate (Tic-TPB) as the sensing element in the presence of dioctylphthalate (DOP) as the plasticizing solvent mediator. The electrode shows nearly Nernstian response for the drug over the concentration range of 1.0×10−2–5.0×10−5M with cationic slope of 58.23mV per concentration decade, and the response time is very short (≤10s). The electrode potential is nearly stable over the pH range 3.8–5.4. The electrode exhibits good selectivity for the Tic with respect to a large number of inorganic ions, amino acids and some pharmaceutical substances. The sensor successfully was used for the determination of Tic in pharmaceutical and biological samples. The average recovery and RSD for the analysis of Tic in pharmaceutical and biological samples using the proposed method obtained 101.04, 98.90% and 1.14, 1.39%, respectively. The results are in good agreement with those obtained by voltammetry method.

鋳型樹脂を用いたジスプロシウム（III）イオン選択性電極の開発

A dysprosium(III)-imprinted polymer was prepared by an imprinting method using dysprosium(III) as the guest and styrene and methacrylate as the host, via a seed emulsion technique. The dysprosium(III)-imprinted polymer adsorbed dysprosium(III) ions more effectively than a non-imprinted polymer. The dysprosium(III) ion-selective liquid membrane electrode, comprising the dysprosium(III)-imprinted polymer (20 mg), polyvinyl chloride (75 mg), and plasticizer nitrophenyl octyl ether (80 mg), showed a Nernstian response of 19.3 mV dec−1 in the range of 10−7 ∼ 10−2 M. The selectivity coefficients of this electrode (log kpot) for potassium(I), copper(II), and samarium(III) ions were –3.71, –5.29, and –3.85, respectively. The electrode was also used for the determination of dysprosium(III) in river water.

Revision of the Osmotic Coefficients, Water Activities and Mean Activity Coefficients of the Aqueous Trivalent Rare Earth Chlorides at T = 298.15 K

The analysis by Wang et al. (J. Solution Chem. 35:1137–1156, 2006) of the osmotic and activity coefficients of fourteen of the aqueous rare earth trichlorides at the temperature 298.15 K is based mainly on the isopiestic results reported by Spedding et al. (J. Chem. Eng. Data 21:341–360, 1976) and Rard and Spedding (J. Chem. Eng. Data 27:454–461, 1982), but corrected for more recent critical reviews of the osmotic coefficients of the KCl(aq) and CaCl2(aq) reference solutions used in these measurements. Also included were the potential difference (emf) measurements by Malatesta et al. (Phys. Chem. Chem. Phys. 4:121–126, 2002) for LaCl3(aq) using cells with a liquid ion-exchange membrane electrode and earlier results for concentration cells with transport for the rare earth trichlorides. Our reexamination of osmotic coefficients calculated from these potential differences of cells with a liquid ion-exchange electrode indicates their values are skewed relative to osmotic coefficients obtained more directly from the isopiestic measurements, being significant higher for molalities between (0.025 and 0.3) mol·kg−1 and significantly lower at higher molalities. As a consequence, the combined results yielded mean, molality-based, activity coefficients that are systematically too large for the light and intermediate rare earths. Although restricted to a narrower molality region of about (0.02–0.04) mol·kg−1, potential difference measurements for aqueous rare earth trichlorides from concentration cells with AgCl(s) electrodes appear to yield more reliable results. The extended ion-interaction model parameters of Wang et al. have been reevaluated using the cited isopiestic results together with osmotic coefficients derived from the concentration cells with transport as reported by Spedding et al. (J. Chem. Eng. Data 21:341–360, 1976). Mean activity coefficients calculated using these new model parameters should be more accurate than those previously reported.

English

Surfactants (surface active agents) are substances which incorporate a hydrophobic non-polar and a hydrophilic polar group, and have the tendency to accumulate at the phase boundary. This feature causes the wide application of surfactants. In 2012, the world surfactant market amounted to 27,040 million USD, and with average annual increase of 6.18 %, this amount in 2017 is estimated at 36,518 million USD2. ASs are used as components in cosmetic formulations, household products, industrial cleaners. Their wide application leads to water pollution, and thus endangers the flora and fauna3. The standard method for the determination of anionic surfactants (ASs) in wastewater is MBAS4 (Methylene Blue Active Substances), while twophase titration5 is used for determining AS in commercial products. Both standard methods have many drawbacks (use of carcinogenic organic solvents, difficulties in determination of anionic surfactants in turbid solution, the subjectivity of the person performing the analysis, inability of auto mation...). The limitations of the standard methods for the determination of AS impose the need for continuous development of new surfactant sensors, which are less expensive, miniaturized, easier to use. The Environmental Protection Act of Croatia does not allow the use of surfactants whose biodegradability is less than 90 %6, thus, the determination of low concentrations of AS in effluents is of great importance. Today, there are a number of techniques that are able to detect, identify, and quantify the surfactant in samples of a complex matrix7. The first methods for determination of ASs were developed from simple volumetric methods5, followed by spectrophotometric methods8,9, chromatography10–12, microfluidic techniques such as flow-injection analysis (FIA)13, capillary electrophoresys14, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR)15. The polymeric membrane ion-selective electrodes (ISEs)16–19 successfully replace standard methods for determination of ASs in various samples. ISEs are a simpler and cost-effective alternative to standard methods. ISEs have evolved from the coated-wire electrodes and liquid polymeric membrane electrodes containing ion-pair based sensing material. The widest use have found ISEs with PVC liquid membrane. Low concentrations of ASs can be determined by ISFET sensors20, biosensors21 or ISEs associated with FIA system. The aim of this study was the application of a newly developed screen-printed microsensor, based on dimethyldioctadecylammonium-tetraphenylborate (DDA-TPB) ion pair as a sensing material, for determination of ASs in industrial wastewater. Particular attention was paid to the determination of low concentrations of ASs. Application of a New Potentiometric Sensor for Determination of Anionic Surfactants in Wastewater

Chemically modified carbon paste sensor for the potentiometric determination of carvedilol in pharmaceutical and biological media

The construction and performance characteristics of a novel potentiometric carbon paste electrode based on incorporation of the ion-association complex of the carvedilol-phosphotungstate were studied. The electrode exhibited Nernstian slope of 58.7mV/decade to carvedilol over a wide concentration range from 3.0×10−7 to 1.0×10−3 M with low detection limit of 1.5×10−7 M. The proposed sensor manifested advantages of fast response, long life time, and most importantly, good selectivities for carvedilol relative to a wide variety of common foreign inorganic cations, biological species and other β-blockers. The advantages of the new sensor were compared to the characteristics of previously reported traditional liquid inner contact PVC membrane electrode. The sensor was successfully applied as an indicator electrode in potentiometric titration and potentiometric determination of carvedilol in carvedilol tablet, blood serum and urine samples. The inclusion complex formation between α- and β-cyclodextrin and carvedilol was studied potentiometrically by the proposed sensor and formation constant of the inclusion complexes were calculated.

A Polymeric Liquid Membrane Electrode Responsive to 3,3′,5,5′-Tetramethylbenzidine Oxidation for Sensitive Peroxidase/Peroxidase Mimetic-Based Potentiometric Biosensing

The oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) has great utility in bioanalysis such as peroxidase/peroxidase mimetic-based biosensing. In this paper, the behaviors of TMB oxidation intermediates/products in liquid/liquid biphasic systems have been investigated for the first time. The free radical, charge transfer complex, and diimine species generated by TMB oxidation are all positively charged under acidic and near-neutral conditions. Electron paramagnetic resonance and visible absorbance spectroscopy data demonstrate that these cationic species can be effectively transferred from an aqueous phase into a water-immiscible liquid phase functionalized by an appropriate cation exchanger. Accordingly, sensitive potential responses of TMB oxidation have been obtained on a cation exchanger-doped polymeric liquid membrane electrode under mildly acidic and near-neutral conditions. By using the membrane electrode responsive to TMB oxidations, two sensitive potentiometric biosensing schemes including the peroxidase-labeled sandwich immunoassay and G-quadruplex DNAzyme-based DNA hybridization assay have been developed. The obtained detection limits for the target antigen and DNA are 0.02 ng/mL and 0.1 nM, respectively. Coupled with other advantages such as low cost, high reliability, and ease of miniaturization and integration, the proposed polymeric liquid membrane electrode holds great promise as a facile and efficient transducer for TMB oxidation and related biosensing applications.

Construction of New Ion Selective Electrodes for Determination Fe(III) and Their Application in Pharmaceutical samples

Liquid membrane electrodes for the determination iron(III) were constructed based on chloramphenicol sodium succinate and iron(III) CPSS-Fe(III) as ion pair complex, with four plasticizers Di-butyl phosphate (DBP); Di-butyl phthalate (DBPH); Di-octyl phthalate (DOP); Tri-butyl phosphate (TBP); in PVC matrix . These electrodes give Nernstian and sub-Nernstian slopes (19.79, 24.60, 16.01 and 13.82mV/decade) and linear ranges from (1x10-5-1x10-2 M, 1x10-5-1x10-2 M, 1x10-6-1x10-2 M and 1x10-5-1x10-2 M) respectively. The best electrode was based on DBP plasticizer which gave a slope 19.79 mV/decade, correlation coefficient 0.9999, detection limit of 9×10-6 M, lifetime 37 day displayed good stability and reproducibility and used to determine iron(III) in pharmaceutical samples. The selectivity coefficient interferences of (K+, Na+, Cu+2, Mn+2, Zn2+, Al3+,Folic acid) were studied using separate and mixed methods for selectivity coefficient determination. The pH and life time of the electrodes were also studied.

BEHAVIOR OF A POLYMERIC LIQUID MEMBRANE ION- SELECTIVE ELECTRODE FOR CHLORIDE ION

Chloride selective polymeric liquid membrane electrode has been developed by using Bis-(2-ethylhexyl) Sebacate (DOS) as plasticizer and 2-[5-(4-nitrophenyl) furyl]-4,5-diphenyl imidazole (FFDFIN) as ionophore. Some parameters of evaluation of the electrode are presented in this work. The constructed electrode showed fast potentiometric response to chloride ion in the concentration range from 10-6 to 10-2 mol.dm-3 with Nernstian slope of -63.43 ± 0.85 mV/decade, response time of 25 seconds and life time of 15 days.

Construction of New Ion Selective Electrodes for Determination Fe(III) and Their Application in Pharmaceutical samples

Liquid membrane electrodes for the determination iron(III) were constructed based on chloramphenicol sodium succinate and iron(III) CPSS-Fe(III) as ion pair complex, with four plasticizers Di-butyl phosphate (DBP); Di-butyl phthalate (DBPH); Di-octyl phthalate (DOP); Tri-butyl phosphate (TBP); in PVC matrix . These electrodes give Nernstian and sub-Nernstian slopes (19.79, 24.60, 16.01 and 13.82mV/decade) and linear ranges from (1x10-5-1x10-2 M, 1x10-5-1x10-2 M, 1x10-6-1x10-2 M and 1x10-5-1x10-2 M) respectively. The best electrode was based on DBP plasticizer which gave a slope 19.79 mV/decade, correlation coefficient 0.9999, detection limit of 9×10-6 M, lifetime 37 day displayed good stability and reproducibility and used to determine iron(III) in pharmaceutical samples. The selectivity coefficient interferences of (K+, Na+, Cu+2, Mn+2, Zn2+, Al3+,Folic acid) were studied using separate and mixed methods for selectivity coefficient determination. The pH and life time of the electrodes were also studied.

Application of 1,2-Dimaleimidobenzene as a Neutral Ionophore in Construction of a Highly Selective Neodymium(III) Liquid Membrane Electrode

Application of 1,2-Dimaleimidobenzene as a Neutral Ionophore in Construction of a Highly Selective Neodymium(III) Liquid Membrane Electrode

Construction of New Ion Selective Electrodes for Determination Chloramphenicol Sodium Succinate and Their Application in Pharmaceutical Samples

A liquid membrane electrodes for the determination chloramphenicol sodium succinate were constructed based on chloramphenicol palmitate and sodium tetraphenyl borate, and with four plasticizers, Di-butyl phthalate (DBPH); Di-butyl phosphate (DBP); Di-octyl phthalate (DOP); Tributyl phosphate (TBP); in PVC matrix. These electrodes give sub- Nernstian slopes (53.98, 51.45, 49.66 and 48.98 mV/decade) and linear ranges from (1x10 -4 -1x10 -1 , 5x10 -4 -1x10 -1 , 1x10 -4 -1x10 -1 , 5x10 -4 -1x10 -1 M) respectively. The best electrode was based on DBPH plasticizer which gave a slope 53.98 mV/decade, correlation coefficient 0.9999, detection limit of 5 x 10 -5 M, lifetime 50 day displayed good stability and reproducibility and used to determine the Chloramphenicol sodium succinate in pharmaceutical samples. The measurement interferences in the presence of K + , Na + , Fe +3 , Al +3 , Cu +2 , Mn +2 , sucrose, Gelatine and Chloramphenicol palmitate were studied using the separated and mixed methods for selectivity coefficient determination. The pH and life time of the electrodes were also studied. The results were compared statistically with UV-spectrophotometeric technique by using F-test.

Determination of Apparent Formation Constants of Eu(III) with Humic Substances by Ion Selective Liquid Membrane Electrode

This is the novel measurement of the apparent formation constants of trivalent lanthanide with humic substances by potentiometric titration using an ion selective electrode (ISE) consisting of bis(diphenylphosphoryl)methane as an ionophore. The ISE prepared exhibited a Nernstian response to the Eu3+ concentration in the test solutions in the presence of humic acid and fulvic acid. The effect of the solution conditions, including the pH, initial metal and humic substance concentrations, and ionic strength, on the formation constants was examined. The present formation constants were compared with the reported data using solvent extraction method.