Neutral Ion Carrier Research Articles

A novel potentiometric screen-printed electrode based on crown ethers/nano manganese oxide/Nafion composite for trace level determination of copper ion in biological fluids.

Copper levels in biological fluids are associated with Wilson's, Alzheimer's, Menke's, and Parkinson's diseases, making them good biochemical markers for these diseases. This study introduces a miniaturized screen-printed electrode (SPE) for the potentiometric determination of copper(II) in some biological fluids. Manganese(III) oxide nanoparticles (Mn2O3-NPs), dispersed in Nafion, are drop-casted onto a graphite/PET substrate, serving as the ion-to-electron transducer material. The solid-contact material is then covered by a selective polyvinyl chloride (PVC) membrane incorporated with 18-crown-6 as a neutral ion carrier for the selective determination of copper(II) ions. The proposed electrode exhibits a Nernstian response with a slope of 30.2 ± 0.3mV/decade (R2 = 0.999) over the linear concentration range 5.2 × 10-9 - 6.2 × 10-3mol/l and a detection limit of 1.1 × 10-9mol/l (69.9ng/l). Short-term potential stability is evaluated using constant current chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). A significant improvement in the electrode capacitance (91.5 μF) is displayed due to the use of Mn2O3-NPs as a solid contact. The presence of Nafion, with its high hydrophobicity properties, eliminates the formation of the thin water layer, facilitating the ion-to-electron transduction between the sensing membrane and the conducting substrate. Additionally, it enhances the adhesion of the polymeric sensing membrane to the solid-contact material, preventing membrane delamination and increasingthe electrode's lifespan. The high selectivity, sensitivity, and potential stability of the proposed miniaturized electrode suggests its use for the determination of copper(II) ions in human blood serum and milk samples. The results obtained agree fairly well with data obtained by flameless atomic absorption spectrometry.

A light activated CMP conjugated 8-aminoquinoline turn-on fluorescent optode for selective determination of Th4+ in an aqueous environment.

A new dibutyl(2-oxo-2-(quinolin-8-ylamino)ethyl)phosphinate (L) was designed, synthesised and developed as a light activated optode for Th4+ determination. The sensing performance of L was studied in solution and in the polymeric membrane phase using absorbance and emission techniques. The neutral ion carrier L exhibits weak fluorescence at 400 nm in CH3CN : H2O (9 : 1, v/v). Upon complexation of L with Th4+, the emission intensity at 486 nm was increased 100-fold due to chelation induced enhanced fluorescence. The L-Th4+ binding interaction was studied using both Hill's and Job's plots. They indicate the formation of complex species in a 2 : 1 ratio with an estimated binding constant of 2.66 × 104 M-2. Complex formation between L and Th4+ was studied by NMR (1H, 31P), FTIR and LC-MS analyses. In order to synthesize a probe for the sensing of Th4+ in 100% aqueous medium, the optode was prepared by immobilizing L as a neutral ion carrier in a PVC support using dioctyl phthalate (DOP) as a membrane solvent. The best performance of the optode was observed with a membrane composition of PVC : L : NaTPB : DOP in proportions of 35 : 5 : 3 : 57 (%, w/w) in the pH range of 4.0-8.0. The optode can detect Th4+ concentrations down to 1.1 nM with a fast response time of 15 s and the optical response remains unaltered even after 3 months; the optode sensor can be regenerated using Na2EDTA solution. Finally, the optode was used for the quantification of Th4+ in various water samples, monazite sand, and gas mantle samples.

Development of highly selective potentiometric thorium(iv) ion-selective electrode: exploration supported with optical and DFT analysis

A new liquid membrane based on PVC composed of L as neutral ion carrier, NaTPB as lipophilic salt dissolved in DOP as plasticizer was developed for selective determination of Th4+.

Construction of a New Selective and Sensitive Nd3+ ion-selective Electrode Based on 1-nitroso-2-naphtol as a Neutral Ion Carrier

Construction of a New Selective and Sensitive Nd3+ ion-selective Electrode Based on 1-nitroso-2-naphtol as a Neutral Ion Carrier

Liquid–liquid extraction of Li+ using mixed ion carrier system at room temperature ionic liquid

An environmentally benign technique for the separation and recovery of lithium (Li+) from aqueous streams, containing mixed metal ions was developed via liquid–liquid extraction (LLE). Hydrophobic room temperature ionic liquids (RTIL) were tested as the main extracting solvents. To increase the metal extraction, a proton-ionizable agent bis(2-ethylhexyl) phosphoric acid (DEHPA) was added into the RTIL. To enhance the metal uptake selectivity, three Li+-selective neutral ion carriers such as 6-hydroxy-dibenzo-14-crown-4, dibenzo-14-crown-4, and tri-n-octyl-phosphine (TOPO) were also used and tested as extractant additives. Among the tested RTILs, phosphonium-based CYPHOS IL 109 was the most stable extractant as it exhibited the lowest loss when contacted with water. Addition of proton-ionizable agent DEHPA in CYPHOS IL 109 afforded a high extraction of multivalent cations with negligible recovery of monovalent metals. On the other hand, the addition of neutral ion carrier TOPO in DEHPA/CYPHOS IL 109 extractant resulted in a selective Li+ uptake which was maximized when the pH of the aqueous solution was maintained at 13, with TOPO/DEHPA molar ratio = 8. The overall process could be a two-stage LLE system wherein the unwanted multivalent cations are initially removed using DEHPA/CYPHOS IL 109 followed by the selective extraction of Li+, using TOPO/DEHPA/CYPHOS IL 109 system.

Design of Highly Selective and Sensitive PVC-Membrane Sensor for Terbium Ions Based on Di(N-succinimidyl)carbonate as a Neutral Ion Carrier

Design of Highly Selective and Sensitive PVC-Membrane Sensor for Terbium Ions Based on Di(N-succinimidyl)carbonate as a Neutral Ion Carrier

A Ho(III) potentiometric polymeric membrane sensor based on a new four dentate neutral ion carrier

In this research, we report a new Ho3+-PVC membrane electrode based on N-(4,5-dimethyl-2-(picolinamido)phenyl)picolinamide (H2Me2bpb) as a suitable ion carrier. Poly vinylchloride (PVC)-based membrane composed of H2Me2bpb with oleic acid (OA) as anionic additives, and o-nitrophenyloctyl ether (NPOE) as plasticized solvent mediator. The sensor exhibits a Nernstian slope of 20.1±0.2mV decade−1 over the concentration range of 1.0×10−6 to 1.0×1−2molL−1, and a detection limit of 5.0×10−7molL−1 of Ho3+ ions. The potentiometric response of the sensor is independent of the solution pH in the range of 3.5–9.4. It has a very short response time, in the whole concentration range (<10s), and can be used for at least eight weeks. The proposed electrode shows a good selectivity towards Ho3+ ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. To assess its analytical applicability the proposed Ho3+ sensor was successfully applied as an indicator electrode in the titration of Ho3+ ion solutions in certified reference materials, alloy samples and for the determination of the fluoride ion in two mouthwash preparations.

Lanthanide Recognition: an Asymetric Erbium Microsensor Based on a Hydrazone Derivative.

N'-(2-hydroxy-1,2-diphenylethylidene)benzohydrazide (HDB) was found tohave a very selective and sensitive behavior towards erbium(III) ions, in comparison tothirteen lanthanide ions, inner transition and representative metal ions and was hence usedas a neutral ion carrier in construction of an Er(III) microelectrode. Theoretical calculationsand conductance studies of HDB to erbium and some other metal ions were carried out andconfirmed selectivity toward Er(III) ions.The best performance was obtained with a membrane contain 3% potassium tetrakis(p-chlorophenyl)borate (KTpClPB) as an anionic additive, 72% dibutyl phthalate (DBP) assolvent mediator, 5% HDB, and 20% poly(vinyl chloride) (PVC). The proposed Er(III)microelectrode exhibits a near Nernstian response of 17.5±0.5 mV per decade of erbiumactivity, and a very wide linear range 1.0×10-3-3.0×10-10 M. It can work well in the pHrange of 3.0-9.0. The lower detection limit (LDL) of the microelectrode was calculated tobe 2.0×10-10 M.

Determination of Vanadyl Ions by a New PVC Membrane Sensor Based on N, N'-bis-(Salicylidene)-2,2-Dimethylpropane-1,3-Diamine

N, N'-bis-(salicylidene)-2,2-dimethylpropane-1,3-diamine (NNPD) was found to be a suitable neutral ion carrier for the construction of a highly selective and sensitive vanadyl membrane sensor. Poly(vinyl chloride) (PVC) based membranes of NNPD with potassium tetrakis (p-chlorophenyl) borate (KTpCIPB) as an anionic excluder and diethyl sebacate (DES), dibutyl phthalate (DBP), banzyl acetate (BA) and o-nitrophenyloctyl ether (NPOE) as plasticizing solvent mediators were investigated in vanadyl membrane sensors. A membrane, composed of NNPD-PVC-KTpCIPB-DES with the ratio 4.0:30.0:1.0:65.0, works well over a wide concentration range (7.0 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> 6 to 1.0 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> 2 M) with a Nernstian slope of 28.8plusmn0.3 mV per decade of activity between pH values of 4.0 and 5.10. The detection limit of the sensor was calculated to be 5.0 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> 6 M. It displays satisfactorily good discrimination toward vanadyl ions with regard to most common transitional metal ions. The proposed sensor demonstrates a short response time (-10 s). It was successfully applied for the determination of vanadyl ions in water samples

A novel Ho(III) sensor based on N,N'-bis(2- pyridinecarboxamide)-1,2-benzene as a neutral ion carrier

N,N'-bis(2- pyridinecarboxamide)-1,2-benzene (H2BPB) was found to have a selective and sensitive behavior towards Ho(III) ion, in comparison to a large number of lanthanide, inner transition and representative metal ions and was hence applied as a neutral ionophore, for preparing an Ho(III) membrane sensor, with high selectivity and sensitivity. The membranes, also contain potassium tetrakis(p-chlorophenyl) borate as an anionic additives, and were tested by using different plasticizing solvent mediators such as benzyl acetate (BA), nitrobenzene (NB), and o-nitrophenyloctyl ether (NPOE). The optimum composition was found to be H2BPB-PVC- KTpClPB-BA with the ratios of 6.0: 30.0: 4.0: 60.0, respectively. Having a Nernstian response of 19.6 ± 0.2 mV per decade of Ho(III) activity, the linear range of the sensor was found to be relatively wide (from 1.0×10-5 to 1.0 ×10-2 mol L-1). It can work well in the pH range of 3.0-11.5. The lower detection limit (LDL) of the sensor was calculated to be 8.0 ×10-6 mol L-1. The excellent Ho(III)-selectivity of the proposed sensor with regard to most common metal ions, and especially, all lanthanide ions, is another advantage that can be mentioned about this sensor. The sensor was successfully used as an indicator electrode for titration of 25 mL of a 1.0 × 10-4 mol L-1 Ho(III) ions with a 1.0 × 10-2 mol L-1 EDTA, and vise versa. To the best of our knowledge this is the first Ho(III)-selective sensor.

Construction of a Highly Selective and Sensitive La(III) Sensor Based on N‐(2‐Pyridyl)‐N′‐(4‐methoxyphenyl)‐thiourea for Nano Level Monitoring of La(III) Ions

AbstractN‐(2‐Pyridyl)‐N′‐(4‐methoxyphenyl)‐thiourea (PMPT) was found to be a suitable neutral ion carrier for the construction of a highly selective and sensitive La(III) membrane sensor. Poly(vinyl chloride) (PVC) based membranes of PMPT with potassium tetrakis (p‐chlorophenyl) borate (KTpClPB) as an anionic excluder and oleic acid (OA), dibutyl phthalate (DBP), benzyl acetate (BA) and o‐nitrophenyloctyl ether (NPOE) as plasticizing solvent mediators were constructed and investigated as La(III) membrane sensors. A membrane composed of PMPT‐PVC‐KTpClPB‐BA with the ratio 8.0 : 35.0 : 3.0 : 54.0 works well over a very wide concentration range (4.0×10−8 to 1.0×10−1 M) with a Nernstian slope of 19.6±0.2 mV per decade of activity between pH values of 4.0 and 9.0. The detection limit of the sensor was calculated to be 2.0×10−8 M (ca. 3.0 ppb). The sensor displays very good discrimination toward La(III) ions with regard to most common metal ions and lanthanide ions. The proposed sensor shows a short response time for whole concentration range (ca. 12 s). For evaluation of the analytical applicability of the La(III) sensor, it was successfully used as an indicator electrode for the titration of La(III) ions with EDTA. It was also applied to the determination of fluoride content of two mouth wash preparation samples and monitoring of La(III) ions in some binary and ternary mixtures.

Fabrication of a highly selective and sensitive Gd(III)-PVC membrane sensor based on N-(2-pyridyl)- N′-(4-nitrophenyl)thiourea

In this work we report the development of a highly selective and sensitive Gd(III) membrane based on N-(2-pyridyl)- N′-(4-nitrophenyl)thiourea (PyTu4NO 2) as an excellent neutral ion carrier. The Gd(III) sensor exhibits a Nernstian slope of 19.95 ± 0.3 mV per decade over the concentration range of 3.0 × 10 −7 to 1.0 × 10 −1 M, and a detection limit of 3.0 × 10 −7 M of Gd(III) ions. The potentiometric response of the sensor is independent of the solution pH in the range of 4.0–9.0. It manifests advantages of low detection limit, fast response time (∼10 s), and most significantly, very good selectivity with respect to a number of lanthanide ions (La, Ce, Sm, and Eu ions). It can be used at least for a period of 8 weeks without any significant divergences in its potential response. To assess its analytical applicability the proposed Gd(III) sensor was successfully applied as an indicator electrode in the titration of Gd(III) ion solutions with EDTA and for the determination of the fluoride ion in two mouth wash preparations. It was also used for the direct monitoring of Gd(III) ions in binary mixtures.

Polymeric Membrane Lanthanum(III)‐Selective Electrode Based on N,N′‐Adipylbis(5‐phenylazo salicylaldehyde hydrazone)

AbstractA recently synthesized azao‐containing Schiff's base N,N′‐adipylbis(5‐phenylazo salicylaldehyde hydrazone) was used as a suitable neutral ion carrier in construction of a highly selective La3+‐PVC membrane electrode. The electrode exhibits a Nernstian response with a slope of 19.4 mV decade−1 over a wide concentration range (1.0×10−6–1.0×10−2 M) and a limit of detection of 4.0×10−7 M (0.05 ppm). The electrode possesses a fast response time of ca. 10 s and can be used for at least 3 months without observing any deviation. The proposed electrode revealed excellent selectivity for La3+ over a wide variety of alkali, alkaline earth, transition and heavy metal ions and could be used in a pH range of 4.0–8.0. The practical utility of the electrode has been demonstrated by its use as an indicator electrode in the potentiometric titration of La3+ ions with EDTA and in determination of F− ion in some pharmaceutical preparations.

Interaction between Silver and Other Heavy Metal Ions and the Ionophore S,S-Dipropyl Pyridine-2,6-dicarbothioate

A detailed study has been made of the interaction of the neutral metal ion carrier S,S-dipropyl pyridine-2,6-dicarbothioate in methanol solution with silver perchlorate. Evidence has been found by potentiometry and confirmed by electrospray mass spectrometry for the existence of both 1:1 and 1:2 metal/ligand complexes. The formation constants of the complexes in methanol have been determined from the potentiometry data and have been shown to be low (K1 ≈ 50 L mol-1, K2 ≈ 8 L mol-1). The value for K1 has been confirmed by NMR and voltammetric measurements. The high Ag+ selectivity found for the ionophore in a PVC-based sensor implies that the formation constants for the ionophore with other metal ions must be even lower than that for the ionophore with silver. A chemical and voltammetric study of the interaction between the ionophore and certain metal ions in methanol has revealed that the ionophore structure breaks down in the presence of Ag+, Hg2+, and Pb2+. The Hg2+ ion is the most reactive of the three...

Fluorescence-based ion sensing using potential-sensitive dyes

Abstract A report is given on the use of potential-sensitive dyes (PSDs) for monitoring the potential created at the membrane-sample interface due to the transport of ions from the (aqueous) sample into the lipid membrane by a neutral ion carrier. In a typical experiment, valinomycin carries potassium ion into the interior of a plasticized PVC membrane, and the PSD (a lipophilic cationic polymethine dye) detects the potential by undergoing a change in fluorescence emission intensity. Unlike in previous sensors based on the use of PSDs, the dye is used as an ion pair with a lipophilic anion. Several mechanisms are discussed that are likely to contribute to the observed change in fluorescence. These include electronic redistribution within the dye, spatial redistribution or voltage-dependent partitioning. In related experiments, changes in fluorescnce polarization have also been observed. Unlike many other kinds of ion optodes, the work function is virtually independent of pH. We finally discuss the microstructures of the membrane, the function of the PSD and the effects of additives.

Validation of carrier-mediated transport of H + and Na + through mobile-site membranes

The response of membranes containing neutral ion carriers of either H + or Na + to an externally-applied potential step was investigated using previously developed techniques for the analysis of charge and mass transport in ion-selective membranes. The results from constant-resistance membranes, e.g. membranes with unperturbed negative site concentration profiles, showed that tridodecylamine behaved as a carrier for H +, and there was no evidence for proton hopping from stationary carriers. In addition, the experimental outcome supported the assumption of a failure of the Donnan exclusion principle at very low pH levels in these membranes. The results from membranes containing the Na + carrier illustrated the significant concentration polarization of ionic species, which was related to significant changes in bulk membrane resistance.

Steady-state-current impedance spectroscopy of plasticized PVC membranes containing neutral ion carriers

Impedance spectroscopy measurements on plasticized PVC ion-selective membranes containing neutral carriers provided evidence for both bulk and interfacial features. Under steady-state currents, the systems showed concentration polarization of neutral carriers and ionic species. The shortage of neutral carriers at one of the interfaces was correlated with the presence of a low-frequency kinetic semi-circle and a Warburg impedance. The changes in ionic concentration profiles were associated with an increase in bulk membrane resistance and Warburg impedance.

Transport processes in membranes containing neutral ion carriers, positive ion complexes, negative mobile sites, and ion pairs

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransport processes in membranes containing neutral ion carriers, positive ion complexes, negative mobile sites, and ion pairsTal M. Nahir and Richard P. BuckCite this: J. Phys. Chem. 1993, 97, 47, 12363–12372Publication Date (Print):November 1, 1993Publication History Published online1 May 2002Published inissue 1 November 1993https://doi.org/10.1021/j100149a043RIGHTS & PERMISSIONSArticle Views120Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts

Optical sensors based on neutral carriers

In a chemical sensor/biosensor there has to be some reversible analyte recognition process of relevant selectivity and a means for translating this process into an adequate signal (transduction). Electrically neutral molecules for the recognition of ions (neutral ion carriers, neutral ionophores) are widely used in ion-selective electrodes (ISEs). In addition to their performance in sensors with potentiometric transduction, they offer exciting possibilities for sensors with optical transduction as well. Even if the analyte recognition by the ionophore does not furnish an adequate optical signal, there are schemes to use them in sensors with optical transduction. Such sensors respond to ratios or products of the activities of the ions participating in the reaction of the sensor membrane with the sample. So far, analytically relevant chemical sensors for Cl −, NO 3 −, Ca 2+, Na +, K +, Pb 2+ (detection limit < 10 −9 mol/l), Zn 2+ and for the recognition of chiral organic cations have been described. The sensor scheme may be extended to electrically neutral analytes. Utilizing electrically neutral analyte carriers, we have been able to design optodes for glucose, ethanol water ammonia (detection limit ∼ 1 ppbv), H 2S and other species. A creatinine carrier has been developed and its implementation into an optode is in progress. Speculations about attractive possibilities will be made.

New lipophilic rhodamines and their application to optical potassium sensing

New lipophilic fluorescent rhodamines were synthesized directly from 3,6-dichlorofluoresceins and the respective long-chain amines with excellent solubility in lipids and lipophilic membranes. Spectrophotometric and luminescent properties of the dyes are reported and discussed with respect to their application in new optical ion sensors. One rhodamine (2a) was applied in a poly(vinyl chloride)-based sensor membrane for continuous and sensitive optical determination of potassium ion, using valinomycin as the neutral ion carrier.