Neutral N,N′-bis(2-pyridinecarboxamide)-1,2-ethane as sensing material for determination of lutetium(III) ions in biological and environmental samples

The biological properties of the lutetium as well as other lanthanide ions, primarily based on their similarity to calcium, have been the bases for research into potential therapeutic applications of lanthanide series since the early part of the twentieth century. In this research, a Lu(III) potentiometric membrane sensor based on N,N′-bis(2-pyridinecarboxamide)-1,2-ethane (PCAE) is described. The sensor exhibits a Nernstian response over a concentration range of 1.0 × 10^? 6 mol L^? 1–1.0 × 10^? 1 mol L^? 1, with a detection limit of 6.0 × 10^? 7 mol L^? 1. The best performance was achieved with a membrane composition, consisting of 30% PVC, 63% o-nitrophenyl octyl ether (NPOE), 5% PCAE and 2% sodium tetraphenylborate (NaTPB). It was found that at the pH range of 4.0–9.0, the potential response of the sensor was not affected by the pH. Furthermore, the electrode presents satisfactory reproducibility, very fast response time (5 s) and relatively good discriminating ability for Lu(III) ions with respect to many common cations and other lanthanide ions. The sensor has been applied to the determination of Lu(III) in human serum and in some soil samples where domestic devices were stored.     

Fabrication of an iron(III) PVC-membrane sensor based on bis-benzilthiocarbohydrazide as a selective sensing material

The construction, performance characteristics, and application of a novel iron(III) membrane sensor based on a new bis-benzilthiocarbohydrazide (BBTC) are reported in this paper. The sensor is prepared by incorporating of BBTC, nitrobenzene (NB), and sodium tetraphenyl borate (NaTPB) into a plasticized poly(vinyl chloride) membrane. The electrode reveals a Nernstian behavior over a wide iron ion concentration range (1.0 × 10^? 2–1.0 × 10^? 7 mol L^? 1), and relatively low detection limit (8.6 × 10^? 8 mol L^? 1). The potentiometric response is independent on the pH of the solution in the range of 1.6–4.3. The electrode shows a very short response time (< 10 s). The proposed electrode can be used for at least nine weeks without any considerable divergence in potentials. It exhibits very good selectivity relative to a wide variety of alkali, alkaline earth, transition and heavy metal ions. In fact, the selectivity of the proposed sensor shows great improvements compared to the previously reported electrodes for the iron ion. Also, the sensors accuracy was investigated in two ways: (i) with the potentiometric titration of a Fe(III) solution with EDTA and (ii) with the Fe(III) monitoring in river and wastewater samples.     

Quantitative monitoring of terbium ion by a Tb3+ selective electrode based on a new Schiff's base

Solution study showed N,N′-bis(5-nitrosalicylidene)-2-aminobenzylamin (L) trends toward Tb³⁺ ion. Then, it was used as a suitable ionophore in construction of terbium ion selective electrode. The electrode with composition of 30% PVC, 65% solvent mediator (NB), 3% ionophore (L) and 2% anionic additive (NaTPB) shows the best potentiometric response characteristics. It displays a Nernstian behavior (20.1 mV decade^?1) over the concentration range 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^?1. The detection limit of the electrode is 6.3 × 10^? 7 mol L^?1. It has a very short response time (~ 10 s) and a useful working pH range of 2.6–9.4 for at least 2 months. The proposed membrane sensor shows excellent discriminating ability towards Tb³⁺ ions with regard to several alkali, alkaline earth, transition and heavy metal ions. To investigate the analytical applicability of the sensor, it was successfully applied to the determination of terbium in certified reference material.     

A novel iron (III)-PVC membrane potentiomeric sensor based on N-(2-hydroxyethyl)ethylenediamine-N,N',N"-triacetic acid

This work introduces a unique ionophore for the selective determination of Fe(III) ions. This ionophore was N-(2-hydroxyethyl)ethylenediamine-N,N′,N″-triacetic acid (NTA), presenting a high affinity towards the trivalent iron cations. The designed sensor exhibited a wide linear response with a slope of 19.5 ± 0.4 mV per decade over the concentration range of 1.0 × 10^− 9–1.0 × 10^− 2 mol L^− 1, while the illustrated detection limit was 3.0 × 10^− 10 mol L^− 1 of the Fe(III) ions concentration. It was concluded that the sensor response was pH independent in the range of 1.8–4.5. The sensor possessed the advantages of short conditioning time, fast response time (10 s) and, especially, good selectivity towards the transition and heavy metal ions as well as some mono, di and trivalent cations. Concerning the electrode lifetime, no considerable potential divergence was noticed for at least 10 weeks. The sensor accuracy was investigated in the potentiometric titration of a Fe(III) solution with EDTA.     

Application of 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea as sensing material for construction of Tm3+-PVC membrane sensor

A thulium(III) membrane sensor was made using 2% sodium tetraphenyl borate (NaTPB), 65% dibutylphthalate (DBP), 30% poly(vinyl chloride) (PVC) and 3% 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea (ET) as an ionophore. Conductometric study shows selectivity of the Et toward Tm³⁺ ions. Nernstian response of 19.6 ± 0.4 mV per decade of thulium concentration was observed, and the electrode worked well in concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with a lower detection limit (LDL) of 7.2 × 10^? 7 mol L^? 1, in a pH range of 4.3–10.4. The selectivity of the sensor over alkaline, alkaline earth, transition and heavy metal ions was also found to be in a satisfactory range. To check the analytical applicability of the proposed Tm³⁺ sensor, it was successfully used as an indicator electrode in analysis of thulium in certified reference materials.     

A novel lutetium(III) PVC membrane sensor based on a new symmetric S–N Schiff's base for Lu(III) analysis in real sample

A novel Lu(III) PVC membrane sensor has been constructed based on a new synthesized symmetric S–N Schiff's base, namely N-[(Z)-1-(2-thienyl)methylidene]-N-[4-(4-{[(Z)-1-(2-thienyl) methylidene]amino}benzyl)phenyl] amine (TBPA). The electrode showed a Nernstian slope of 19.8 ± 0.5 mV per decade across a wide concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with a detection limit of 7.2 × 10^? 7 mol L^? 1. The proposed sensor showed high selectivity toward Lu(III) ion in comparison with common alkaline, alkaline earth, transition, and heavy metals specially lanthanide ions, and could be used over a pH range of 2.7–10.6. It can be used for at least 2 months without any considerable divergency in potentials and it has a relatively fast response time of < 10 s. The sensor was effectively used as an indicator electrode in the potentiometric titration of Lu(III) ions with EDTA. The constructed sensor accuracy was investigated by the monitoring of Lu(III) ion in mixtures of two and three different ions.     

Fabrication of a PVC membrane samarium(III) sensor based on N,N′,N″-tris(4-pyridyl)trimesic amide as a selectophore

A new ion-selective electrode for Sm^3 + ion is described based on the incorporation of N,N′,N″-tris(4-pyridyl)trimesic amide (TPTA) in a poly(vinylchloride) (PVC) matrix. The membrane sensor comprises nitrobenzene (NB) as a plasticizer, and oleic acid (OA) as an anionic additive. The sensor with the optimized composition shows a Nernstian potential response of 19.8 ± 0.5 mV decade^? 1 over a wide concentration range of 1.0 × 10^? 2 and 1 × 10^? 6 mol L^? 1, with a lower detection limit of 4.7 × 10^? 7 mol L^? 1 and satisfactor applicable pH range of 3.6–9.2. Having a short response time of less than 10 s and a very good selectivity towards the Sm^3 + over a wide variety of interfering cations (e.g. alkali, alkaline earth, transition and heavy metal ions) the sensor seemed to be a promising analytical tool for determination of the Sm^3 +. Hence, it was used as an indicator electrode in the potentiometric titration of samarium ion with EDTA. It was also applied to the direct samarium recovery in binary mixtures.     

A new aluminum(III)-selective potentiometric sensor based on N,N′-propanediamide bis(2-salicylideneimine) as a neutral carrier

This work describes the fabrication of a selective polymeric membrane potentiometric sensor for Al³⁺ ion based on N,N′-propanediamide bis(2-salicylideneimine) (NPBS) as a neutral carrier. The proposed sensor, with optimum membrane composition, exhibited an excellent near-Nernstian response for Al³⁺ ion ranging from 7.9 × 10^? 7 to 1.0 × 10^? 1 mol/L with a detection limit of 4.6 × 10^? 7 mol/L and a slope of 19.4 ± 0.3 mV/dec in pH 3.0 nitrate solution at 25 °C. It showed a relatively fast response time (8 s), suitable reproducibility and stability, and good selectivity towards Al³⁺ ion. The operational pH range of the proposed sensor was 2.5–4.0. The response mechanism was discussed in view of UV–visible spectroscopy and the alternating current (AC) impedance technique. In addition, the proposed sensor was successfully used as an indicator electrode in potentiometric titration of Al³⁺ ion and in the direct determination of Al³⁺ ion in real samples.     

Praseodymium analysis in aqueous solution by Pr3+–PVC membrane sensor based on N,N′-bis(4-hydroxysalicylidene)-1-3-phenylenediamine

A new Pr³⁺ poly vinyl chloride PVC membrane sensor based on a membrane containing 3% N,N′-bis(4-hydroxysalicylidene)-1-3-phenylenediamine (HSPDA) as an ionophore, 2% sodium tetraphenyl borate (NaTPB) as an anionic additive, 65% benzyl acetate (BA) as solvent mediator and 30% poly(vinyl chloride) was prepared. This sensor responds to praseodymium ion in a wide linear dynamic range of 1.0 × 10^?6 to 1.0 × 10^?2 mol L^?1 with Nernstian slope of 19.8 ± 0.4 mV per decade and a detection limit of 5.7 × 10^?7 mol L^? 1 in pH range of 3.1 to 9.8. It has a fast response time of ~5 s in the whole concentration range, and can be used for at least 2 months without any considerable divergences in the potentials. The proposed sensor displays an excellent selectivity for Pr³⁺ ions with respect to a large number of alkali, alkaline earth, transition and heavy metal ions. The developed sensor was successfully applied as an indicator electrode in Pr³⁺ ion potentiometric titration with EDTA, and in direct determination of fluoride ion in two mouth wash samples.     

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

In this research, we report a new Ho^3 +-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 ± 0.2 mV decade^? 1 over the concentration range of 1.0 × 10^? 6 to 1.0 × 1^? 2 mol L^? 1, and a detection limit of 5.0 × 10^? 7 mol L^? 1 of Ho^3 + 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 (< 10 s), and can be used for at least eight weeks. The proposed electrode shows a good selectivity towards Ho^3 + ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. To assess its analytical applicability the proposed Ho^3 + sensor was successfully applied as an indicator electrode in the titration of Ho^3 + ion solutions in certified reference materials, alloy samples and for the determination of the fluoride ion in two mouthwash preparations.     

Potentiometric detection of silver (I) ion based on carbon paste electrode modified with diazo-thiophenol-functionalized nanoporous silica gel

For the first time, triazene compound functionalized silica gel was incorporated into carbon paste electrode for the potentiometric detection of silver (I) ion. A novel diazo-thiophenol-functionalized silica gel (DTPSG) was synthesized, and the presence of DTPSG acted as not only a paste binder, but also a reactive material. The electrode with optimum composition, exhibited an excellent Nernstian response to Ag⁺ ion ranging from 1.0 × 10^? 6 to 1.0 × 10^? 1 M with a detection limit of 9.5 × 10^? 7 M and a slope of 60.4 ± 0.2 mV dec^? 1 over a wide pH range (4.0–9.0) with a fast response time (50 s) at 25 °C. The electrode also showed a long-time stability, high selectivity and reproducibility. The response mechanism of the proposed electrode was investigated by using AC impedance. Moreover, the electrode was successfully applied for the determination of silver ions in radiology films, and for potentiometric titration of the mixture solution of Cl^? and Br^? ions.     

A comparative study on fabrication of Mn2 + selective polymeric membrane electrode and coated graphite electrode

Poly(vinyl chloride)-based membranes of two ligands 2,4-bis(2-acetoxybenzylamino)-6-phenyl-1,3,5-triazine (L₁) and N2,N4-di(cyanoethyl)-2,4-bis(2-acetoxybenzylamino)-6-phenyl-1,3,5-triazine (L₂) were fabricated and explored as Mn^2 + ion selective electrodes. The performance of the polymeric membranes electrodes of ionophores with different plasticizers (dibutylphthalate, benzoic acid, o-nitrophenyloctyl ether, 1-chloronapthalene and tri-n-butylphosphate) and anion excluders (sodium tetraphenylborate and potassium tetrakis p-(chloro phenyl)borate) was looked in to and the better results were obtained with the membrane having composition L₂: NaTPB: DBP: PVC as 6: 3: 56: 35 (w/w; mg). The coated graphite electrode (CGE) with same composition was also fabricated and investigated as Mn^2 + selective electrode. It was found that CGE showed better response characteristics than PME. The potentiometric response of CGE was independent of pH in the range 3.0–9.0 exhibiting the Nernstian slope 29.5 ± 0.3 mV decade^? 1 of activity and working concentration range 4.1 × 10^? 7–1.0 × 10^? 1 mol L^? 1 with a limit of detection 6.7 × 10^? 8 mol L^? 1. The electrode showed a fast response time of 12 s with a shelf life of 105 days. The proposed CGE could be successfully used for the determination of Mn^2 + ions in different water, soil, vegetables and medicinal plants also used as an indicator electrode in potentiometric titration with EDTA.     

Dysprosium selective potentiometric membrane sensor

A novel Dy(III) ion-selective PVC membrane sensor was made using a new synthesized organic compound, 3,4-diamino-N′-((pyridin-2-yl)methylene)benzohydrazide (L) as an excellent sensing element. The electrode showed a Nernstian slope of 19.8 ± 0.6 mV per decade in a wide concentration range of 1.0 × 10^? 6–1.0 × 10^? 2 mol L^? 1, a detection limit of 5.5 × 10^? 7 mol L^? 1, a short conditioning time, a fast response time (< 10 s), and high selectivity towards Dy(III) ion in contrast to other cations. The proposed sensor was successfully used as an indicator electrode in the potentiometric titration of Dy(III) ions with EDTA. The membrane sensor was also applied to the F^– ion indirect determination of some mouth washing solutions and to the Dy^3 + determination in binary mixtures.     

New potentiometric sensor for the determination of iodine species

The characteristics, performance and application of novel triiodide potentiometric sensor based on ion-pair of Rhodamine B triiodide as a membrane carrier are described. The electrode has a linear dynamic range between 1 × 10^? 6 and 1 × 10^? 1 M, with a Nernstian slope of 68 ± 1 mV pC^? 1 and detection limit of 3.9 × 10^? 7 M. Fast and stable response, good reproducibility, long-term stability, very good selectivity over a large number of common organic and inorganic anions, applicability over a pH range of 2–10 are demonstrated. The proposed sensor has been applied for potentiometric determination of some iodine species.     

Nickel analysis in real samples by Ni2 + selective PVC membrane electrode based on a new Schiff base

A newly synthesized Schiff base 3-aminoacetophenonesemicarbazone (AAS) has been used for the preparation of Ni^2 + selective PVC membrane electrode. The proposed electrode exhibits a Nernstian response over the nickel concentration range of 1.0 × 10^? 7 to 1.0 × 10^? 2 mol L^? 1 with a slope of 30.0 ± 0.3 mV/decade of concentration. The limit of detection as determined from the intersection linear segment of the calibration plot is 5.1 × 10^? 8 mol L^? 1. The electrode shows good selectivity towards nickel with respect to several alkali, alkaline earth, transition and heavy metal ions. The response time of the electrode is very fast (≥ 10 s) and can be used for 17 weeks in the pH range of 2.0–9.8. The electrode can also be used in partially non-aqueous media having up to 20% (v/v) methanol, ethanol or acetone content with no significant change in the value of slope or working concentration range. To investigate the analytical applicability of the electrode, it was successfully applied as an indicator electrode in Ni^2 + ion potentiometric titration with EDTA, and in direct determination of nickel(II) in real samples.     

Gadolinium(III) ion selective sensor using a new synthesized Schiff's base as a sensing material

According to a solution study which showed a selective complexation between N,N′-bis(methylsalicylidene)-2-aminobenzylamine (MSAB) and gadolinium ions, MSAB was used as a sensing element in construction of a gadolinium(III) ion selective electrode. Acetophenon (AP) was used as solvent mediator and sodium tetraphenyl borate (NaTPB) as an anion excluder. The electrode showed a good selectivity towards Gd(III) ions over a wide variety of cations tested. The constructed sensor displayed a Nernstian behavior (19.7 ± 0.3 mV/decade) in the concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with detection limit of 5.0 × 10^? 7 mol L^? 1 and a short response time (< 10 s). The working pH range of the electrode was 3.5–10.1 and lifetime of the sensor was at least 10 weeks. Analysis of certified reference materials confirmed the accuracy of the proposed sensor. The electrode was successfully applied as an indicator electrode in gadolinium titration with EDTA.     

Construction of Tm3+-PVC membrane sensor based on 1-(2-thiazolylazo)-2-naphthol as sensing material

In this study, a new thulium(III) membrane sensor was constructed. The proposed membrane sensor was fabricated based on a membrane containing 2% sodium tetraphenyl borate (NaTPB) as an anionic additive, 65% benzyl acetate (BA) as solvent mediator, 3% 1-(2-thiazolylazo)-2-naphthol (TN) as ionophore, and 30% poly(vinyl chloride) (PVC). The proposed Tm³⁺ electrode exhibits a Nernstian response of 19.5 ± 0.2 mV per decade of thulium concentration, and has a lower detection limit of 8.7 × 10^? 7 mol L^? 1. The linear range of the sensors was 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1. It works well in the pH range of 3.2–9.5. Moreover, the recommended selective sensor revealed a comparatively satisfactory selectivity regarding most of the alkali, alkaline earth, some transition and heavy metal ions. The membrane sensor was applied to the determination of fluoride ions in mouth wash samples.     

Designing and synthesis of bis(2,4-dihydroxybenzylidene)-1,6-diaminohexane and its efficient application as neutral carrier for preparation of new copper selective electrode

A new copper carbon paste electrode (CPE) based on incorporation bis(2, 4-dihydroxybenzyliden)-1,6-diaminohexane (DHBDAH) in graphite powder matrix has been described. The influence of variables including an amount of graphite, sodium tetraphenylborate (NaTPB), DHBDAH and nujol on the Cu²⁺ carbon paste electrode response was studied and optimized. The optimum carbon paste composition was set as follows, graphite powder: NaTPB: Nujol: DHBDAH with amount of 150:2.3:30:4 mg, respectively. At the optimum conditions, the potential response is linear over the concentration range of 5.0 × 10^? 8 to 1.0 × 10^? 1 mol L^? 1 with a Nernstian slope of 29.5 ± 1.1 mV per decade of Cu²⁺ ion concentration. The good performance of electrode such as low detection limit of (LOD) (4 × 10^? 8 mol L^? 1), wide applicable pH range (2.5–5.5), fast response time (?10 s) and adequate shelf life (69 days) indicate the utility of the proposed electrode for evaluation of Cu²⁺ ion content in various analysis. Due to moderate potentiometric selectivity coefficients of proposed electrode obtained by fixed interference method (FIM) and separate solution method (SSM), the proposed electrode successfully can be applied for the determination of Cu²⁺ ions content in some real samples.     

Hexadecylpyridinium surfactant modified zeolite A as an active component of a polymeric membrane sulfite selective electrode

Zeolite A was synthesized from waste porcelain and modified by hexadecylpyridinium surfactant to change the cation exchanger property of the raw zeolite to anion exchanger property in the obtained surfactant modified zeolite (SMZ). The SMZ was used as an active ingredient component of a membrane selective sulfite electrode. The electrode was fully characterized in terms of composition, response time, thermal stability and usable pH range. The sensor showed suitable response to sulfite in the concentration range of 8.0 × 10^? 7 to 1.0 × 10^? 1 mol L^? 1, with a detection limit of 5.0 × 10^? 7 mol L^? 1 and a slope of ? 29.5 ± 0.8 mV per decade of sulfite concentration.     

Highly selective determination of perchlorate by a novel potentiometric sensor based on a synthesized complex of copper

In this paper, a highly selective poly (vinyl chloride) (PVC) membrane electrode based on (1, 9-dibenzyl-1, 3, 7, 9, 11, 15-hexaaza cyclohexa decane) copper(II) perchlorate; [Cu((benzyl)₂[16]aneN₆)](ClO₄)₂; as a synthesized ionophore, for perchlorate-selective electrode is reported. The influence of membrane composition, pH and possible interfering anions were investigated on the response properties of the electrode. The sensor responds to perchlorate ion in linear range from 1.0 × 10^? 6 to 1.0 × 10^? 1 M with a slope ? 59.4 ± 0.3 mV per decade. The limit of detection of the electrode was 4.0 × 10^? 7 M ClO₄^–. Selectivity coefficients indicate a good discriminating ability towards ClO₄^– ion in comparison to other anions. The proposed sensor has a fast response time of about 7 s and can be used for at least 2 months without any considerable divergence in potential. Due to importance of analysis of perchlorate in water samples, this selective electrode was applied as potentiometric sensor in determination of perchlorate ion in real samples.