Highly Sensitive Membrane Electrode Based on a Copper(II)-bis(N-4-Methylphenyl-Salicyldenaminato) Complex for the Determination of Chromate

A highly sensitive polyvinyl chloride (PVC) membrane electrode, based on copper(II)-bis(N-4-methylphenyl-salicyldenaminato) complex, (CuL₂), as a carrier was reported for the determination of chromate ion. The influence of membrane composition, pH, and possible interfering anions on the response of the ion selective electrode was investigated. The sensor exhibited a Nernstian slope of 29.7 mV per decade when the chromate concentration was varied between 2.0 × 10^?7–1.50 × 10^?2 M in a wide pH range (6.0 to 9.0). The detection limit of the ion selective electrode was 9.2 × 10^?8 M. The proposed sensor was used for at least 4 months without any considerable divergence in potential. It was applied as indicator electrode in potentiometric titration of chromate ion with Pb²⁺ and Tl⁺.     

Highly Selective and Sensitive Triiodide PVC‐Membrane Electrode Based on a New Charge‐Transfer Complex of Bis(2,4‐Dimethoxybenzaldehyde)butane‐2,3‐Dihydrazone with Iodine

In this work, a highly selective membrane triiodide sensor based on a new charge‐transfer complex of bis(2,4‐dimethoxybenzaldehyde)butane‐2,3‐dihydrazone with iodine (Iodide Charge Transfer complex: ICT) as membrane carrier is introduced. The influences of five different solvent mediators on sensitivity and selectivity of the proposed sensor were considered. The best performance was obtained with the membrane composition containing 30% poly (vinyl chloride), 63% DBP, 5% ICT and 2% HTAB. The electrode shows a Nernstian behavior over a very wide triiodide ion concentration range (1.0 × 10^?7‐1.0 × 10^?2 M), and a detection limit value of 8.0 × 10^?8 M. The effect of pH on the potentiometric response of the sensor was also studied, and it was found that the response of the electrode is independent of the pH of the solution in the pH range of 4.0–10. The proposed sensor has a very fast response time (< 12 s), and good selectivities relative to a wide variety of common inorganic and organic anions, including iodide, acetate, bromide, chloride, fluoride, nitrite, nitrate, sulfite, sulfate, cyanide and thiocyanate. In fact the selectivity behavior of the proposed triiodide ion‐selective electrode shows great improvements compared to the previously reported electrodes for triiodide ion. The proposed membrane sensor can be used for at least 6 months without any divergence in the potentials. The electrode was successfully applied as an indicator electrode in the titration of triiodide with thiosulfate ion.     

Application of Tetra Cyclohexyl Tin(IV) as an Anionic Carrier for the Construction of a New Salicylate Membrane Sensor

A new tin complex namely tetracyclohexyl tin(IV) (TCHT) was synthesized and used as the ion carrier for the construction of a highly selective salicylate sensor. This sensor shows a Nernstian response to salicylate ions over a very wide concentration (1.0 × 10^?7–1.0 × 10^?1 M) in a pH range of 5.5–10.5. The optimum selectivity and response could be obtained for a membrane incorporating 30% PVC, 61% BA, 3% of cationic additive (HTAB) and 6% of TCHT. The response time of the electrode is very short in the whole concentration range (15 s). The electrode also shows an excellent discriminating ability for salicylate ions with respect to the most common organic and inorganic anions including chloride, sulfate, nitrate, nitrite, cyanide, sulfite, iodide, thiocyanate, phosphate, acetate, oxalate, citrate, and tartarate ions. The detection limit of the proposed sensor is 8.0 × 10^?8 M. The electrode was successfully used for determining the concentration of salicylate ion in synthetic serums.     

Potentiometric Iodide Selectivity of Polymer‐Membrane Sensors Based on Co(II) Triazole Derivative

The 3‐amion‐5‐mercapto‐1,2,4‐triazole cobalt(II) [Co(II)AMETR] was used as a new carrier for preparing polymeric membrane selective sensor which exhibited high affinity for iodide ion. The effects of membrane composition, pH, the influence of lipophilic ion additives and plasticizer on the response characteristics of the sensor were investigated. The sensor showed a near Nernstian slope of ?56.6 mV/decade for I^? ion over a wide concentration range from 8.5×10^?7 to 1.0×10^?1 M with a low detection limit of 5.1×10^?7 M. The sensor has a fast response time and could be used over a wide pH range of 2–8. The response mechanism is discussed in view of the AC impedance technique. The sensor was successfully applied to direct determination of iodide content in environmental water samples and mouth wash samples.     

Novel Ytterbium(III) Selective Membrane Sensor Based on N‐(2‐Pyridyl)‐N′‐(2‐Methoxyphenyl)‐Thiourea as an Excellent Carrier and Its Application to Determination of Fluoride in Mouth Wash Preparation Samples

The construction, performance, and applications of a novel ytterbium(III) sensor based on N‐(2‐pyridyl)‐N′‐(2‐methoxyphenyl)‐thiourea (PMT), as an excellent carrier, in plasticized poly(vinyl chloride) PVC matrix, is described. The influences of membrane composition and pH on the potentiometric response of the sensor were investigated. The sensor exhibits a nice Nernstian response for Yb(III) ion over a wide concentration range of 4 decades of concentration (1.0×10^?6–1.0×10^?2 M), and a detection limit of 5.0×10^?7 M. The response time of the electrodes is between 8 and 10 s, depending on the concentration of ytterbium(III) ions. The proposed sensor can be used for about 8 weeks without any considerable divergence in potential. The sensor revealed very good selectivity for Yb(III) in the presence of several metal ions. The best performance was observed for the membrane containing; 30% PVC, 59% o‐nitrophenyloctyl ether (NPOE) as solvent mediator, 7% PMT, and 4% sodium tetraphenyl borate (NaTPB). It was successfully applied as indicator electrodes in the potentiometric titration of Yb(III) with EDTA and for the determination of fluoride ion in two mouth wash formulations. The proposed La(III) sensor was found to work well under laboratory conditions. It was also used as an indicator electrode in titration of a 1.0×10^?4 M of Yb(III) with a standard EDTA solution (1.0×10^?2 M). It was also used for determination of Yb(III) ion in Xenotime .     

Erbium(III) PVC Membrane Ion-Selective Sensor based on 4-(2-Thiazolylazo)resorcinal

Abstract

4-(2-Thiazolylazo)resorcinol (TR) was used as a new compound to play the role of an excellent ion carrier in the fabrication of an Er(III) membrane electrode. The electrode shows a very good selectivity toward Er(III) ions over a wide variety of cations, including alkali, alkaline earth, transition, and heavy-metal ions. The proposed sensor exhibits a Nernstian behavior (with slope of 19.6 ± 0.6 mV per decade) over a wide concentration range (1.0 × 10^?6 to 1.0 × 10^?2 M). The detection limit of the sensor is 6.6 × 10^?7 M. It has a very short response time, in the whole concentration range (～10 s), and can be used for at least 12 weeks in the pH range of 2.8–9.3. The proposed sensor was successfully applied as an indicator electrode for the potentiometric titration of a Er(III) solution, with EDTA. It was also successfully applied to the F^? ion determination in some mouthwashing solutions.     

A New Pentadentate S‐N Schiffs' Base as a Novel Ionophore in Construction of a Novel Gd(III) Membrane Sensor

We found that bis(thiophenal) pyridine‐2,6‐diamine (BPD) can be used as an excellent ion carrier to prepare a gadolinium‐selective PVC‐based membrane sensor. The use of oleic acid (OA) and potassium tetrakis(p‐chlorophenyl borate)(KTKpClPB), as anionic additives, and dibutyl phthalate (DBP), acetophenone (AP) and nitrobenzene (NB), as plasticizing solvent mediators was investigated. The best performance was observed with a membrane having the composition of 30% PVC; 62% BA; 5% BPD; and 3% KTKpClPB. The resulting sensor works well over a relatively wide concentration range (1.0×10^?6–1.0×10^?1 M) with a Nernstian slope of 19.4±0.4 mV per decade of gadolinium activity over a wide pH range (3.5–8.0). The limit of detection of the sensor is 7.0×10^?7 M (ca. 110 ng mL^?1). The proposed electrode shows excellent discriminating ability toward gadolinium ions with regard to common alkali, alkaline earth, transition, heavy metal ions, and specially, lanthanide ions. The proposed sensor was applied as an indicator electrode for titration of gadolinium ions with EDTA.     

Highly Selective PVC‐Based Membrane Electrode Based on 2,6‐Diphenylpyrylium Fluoroborate

A highly selective PVC‐membrane electrode based on 2,6‐diphenylpyrylium fluoroborate is presented. The electrode reveals a Nernstian potentiometric response for sulfate ion over a wide concentration range (5.0 × 10^?6‐1.0 × 10^?1 M). The electrode has a response time of about 10 s and can be used for at least 2 months without any divergence. The proposed sensor revealed very good selectivities for sulfate over a wide variety of common organic and inorganic anions and could be used over a wide pH range (2.5–9.5). The detection limit of the sensor is 3.0 × 10^?6 M. It was successfully applied to the direct determination of salbutamol, paramomycin tablets, and as an indicator electrode for potentiometric titration of sulfate ions with barium ions.     

Carbon nanotube composite PVC coated stainless steel disc electrode for detection of Ga(III)

This study demonstrates the application of the composite of multi-walled carbon nanotube polyvinylchloride (MWCNT-PVC) based on Bismarck Brown R for gallium sensor. MWCNT has a role to enhance the hydrophobicity of the membrane, which leads to a more stable potential signal. In addition by applying polypyrrol on the surface of this sensor a reduction in the drift of potential occurred and equilibrium potential was achieved faster. Compared to previous studies, using a stainless steel disc instead of a wire electrode causes to obtain an easily and more homogeneous coated electrode. The sensor shows a good Nernstian slope of 19.70?±?0.37?mV?decade^?1 in a wide linear range concentration of 1.0?×?10^?7 to 1.0?×?10^?2?M of Ga(NO₃)₃. The detection limit of this electrode was 7.7?×?10^?8?M of Ga(NO₃)₃. This proposed sensor is applicable in a wide pH range of 2 to 8. It has a short response time of about 8?s and has a good selectivity over twenty four various metal ions. The practical analytical utility of this electrode is demonstrated by measurement of Ga(III) in rock and different water samples.     

Direct determination of pesticides in vegetable samples using gold nanoelectrode ensembles

Gold nanowires were produced by electrodeposition in polycarbonate membrane, with an average diameter of 200 nm and a height of about 2 μm. The nanowire array prepared by the proposed method can be considered as nanoelectrode ensembles (NEEs). An amperometric pesticides sensor based on gold NEEs has been developed and used for determination of phoxim and dimethoate in vegetable samples. The electrochemical performance of the gold NEEs has also been studied by the amperometric method. The electrode provided a linear response over a concentration range of 5.9 × 10^?5 to 1.2 × 10^?2 M for phoxim with a detection limit of 4.8 × 10^?6 M and 6.3 × 10^?5 to 1.1 × 10^?2 M for dimethoate. This sensor displayed high sensitivity and selectivity, long-term stability and wide linear range. In addition, the ellipsis of enzyme and the reactivation of enzyme make the operation simple. This sensor has been used to determine pesticides in a real vegetable sample.     

Thiocyanate-selective membrane electrode based on cobalt(III) Schiff base as a charge carrier

A highly selective polyvinylchloride (PVC) membrane electrode based on Schiff base complex i.e. [Cobalt (Salpen) (PBu₃)] ClO4 · H2O (Salpen = bis(salycilaldehyde)propylene diamine) is reported as new carrier for thiocyanate selective electrode by incorporating the membrane ingredients on the surface of graphite electrodes. The proposed electrode possesses a very wide Nernestian linear range to thiocyanate from 1.0 × 10^?6 to 1.0 × 10^?1 M with slope of ?59.05 ± 0.91 mV per decade of thiocyanate concentration, very low detection limit (8.0 × 10^?7 M) and good thiocyanate selectivity over the wide variety of other anions. Fast and stable response, good reproducibility, long-term stability, applicability over a wide pH range (2.8–9.8) are advantages of the reported electrode. The sensor has a response time of <5 s and can be used for at least 14 weeks without any considerable change in respective potential response. The proposed electrode was used for the determination of thiocyanate in saliva, wastewater and human urine with satisfactory results and good agreement with colorimetric as reference method.     

Terbium(III) Ion-Selective Electrochemical Sensor Based on Hematoporphyrin

Abstract

A polyvinyl chloride (PVC) based membrane sensor for terbium ions was prepared by employing Hematoporphyrin (HP) as an ionophore. The sensor revealed a very good selectivity (expect for the Fe³⁺ion) with respect to common alkali, alkaline earth and heavy metal ions. The plasticized membrane electrode exhibits a Nernstian response for Tb³⁺ ions over a wide concentration range (1.0 × 10^?6 ? 1.0 × 10^?2 M) with a slope of 19.8±0.3 mV per decade and low detection limit of 7.4 × 10^?7 M. The developed sensor was used in determination of F^? in mouth wash preparation sample.     

A Highly Selective and Sensitive Barium(II)‐Selective PVC Membrane Based on Dimethyl 1‐Acetyl‐8‐oxo‐2,8‐dihydro‐ 1H‐pyra‐zolo[5,1‐a]isoindole‐2,3‐dicarboxylate

A poly(vinyl chloride)‐based membrane of dimethyl 1‐acetyl‐8‐oxo‐2,8‐dihydro‐1H‐pyra‐zolo[5,1‐a]isoindole‐2,3‐dicarboxylate as a neutral carrier with sodium tetraphenylborate (NaTPB) as an anion excluder and 2‐nitrophenyl octyl ether (NPOE) as plasticizer was prepared and investigated as a Ba(II)‐selective electrode. The electrode exhibits a Nernstian slope of 29.7±0.4 mV per decade over a wide concentration range (1.0×10^?6 to 1.0×10^?1 M) with a detection limit of 7.6×10^?7 M between pH 3.0 and 11.0. The response time of the sensor is about 10 s and it can be used over a period of 2 months without any divergence in potential. The proposed membrane sensor revealed good selectivity for Ba(II) over a wide variety of other metal ions. It was successfully used in direct determination of barium ions in industrial wastewater samples.     

Fabrication of an optical sensor based on the immobilization of Qsal on the plasticized PVC membrane for the determination of copper(II)

A novel optical sensor has been proposed for sensitive determination of Cu(II) ion in aqueous solutions. The copper sensing membrane was prepared by incorporating Qsal (2-(2-hydroxyphenyl)-3H-anthra[2,1-d]imidazole-6,11-dione) as ionophore in the plasticized PVC membrane containing tributyl phosphate (TBP) as plasticizer. The membrane responds to Cu(II) ion by changing color reversibly from yellow to dark red in acetate buffer solution at pH 4.0. The proposed sensor displays a linear range of 6.3 × 10^?7?1.00 × 10^?4 M with a limit of detection of 3.3 × 10^?7 M. The response time of the optical sensor was about 3?C5 min, depending on the concentration of Cu(II) ions. The selectivity of the optical sensor to Cu(II) ions in acetate buffer is good. The sensor can readily be regenerated by hydrochloric acid (0.1 M). The optical sensor is fully reversible. The proposed optical sensor was applied to the determination of Cu(II) in environmental water samples.     

Highly Selective Molecularly Imprinted Polymer Sensor for Indium Detection Based on Recognition of In‐Alizarin Complexes

A highly selective molecularly imprinted polymer electrochemical sensor for In³⁺ detection was proposed. In³⁺ ion was chelated with alizarin red S to form a complex In‐ARS. The complex was used as the template molecule to prepare a molecularly imprinted polymer (MIP) based sensor. The selectivity of the sensor was improved significantly due to the three‐dimensional specific structure of the complex, and the selective complexation of ligands for metal ions. Moreover, the sensitivity of the proposed sensor was improved by recording the reductive current of ligand in complex. This technique was highly sensitive for quantitative analysis of In³⁺ in the concentrations ranged from 1×10^?8 mol/L to 2.5×10^?7 mol/L with a detection limit of 4.7×10^?9 mol/L. The proposed sensor has been successfully used in detecting In³⁺ in real samples.     

Original Potentiometric Ytterbium(III) PVC-Membrane Sensor Based on N1,N2-Bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide

Abstract

In this work, we describe the construction, performance, and applications of an original ytterbium(III) sensor based on N¹,N²-bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide (BHDEH), which acts as a suitable carrier. Because it has a low detection limit of 4.2 × 10^?7 M, the sensor response for the Yb(III) ion is Nernstian over a wide concentration range: four decades of concentration (1.0 × 10^?6 to 1.0 × 10^?2 M). The response time of the electrode is less than 10 s, it can be used in the pH range of 3.2–8.3, and its duration is at least 2 months without any considerable potential divergence. The sensor revealed very good selectivity for Yb(III) in the presence of several metal ions. To investigate the sensor analytical applicability, it was tested as an indicator electrode in the potentiometric titration of Yb(III) solution with standard EDTA solution. The proposed electrode was also used to determine fluoride ions in mouthwash.     

A Novel Sulfate Polymeric Membrane Sensor Based on a New Bis‐Pyrylium Derivative

A novel ion‐selective polymeric membrane sensor based on pyrylium‐4,4‐(1,4‐phenylen) bis[2,6‐bis(2‐naphthyl)]‐bis[tetrafluoroborate] (PBGNB) as an excellent sensing material is successfully developed. The electrode possesses the advantages of a very low detection limit (5.0×10^?8 M), a wide working concentration range (1.0×10^?8?1.0×10^?1 M) and specially, a high sulfate selectivity over most common organic and inorganic anions. The sensor displays Nernstian behavior (slope of 29.5±0.5 mV per decade) in a wide pH range (3.0–8.5). It shows a short response time in the whole concentration range (ca. 10 s). The electrode was used as an indicator electrode in the potentiometric titration of sulfate ions with barium ions. The proposed sensor was successfully applied to the direct determination of salbutamol sulfate and paromomycin sulfate.     

A Novel Al(III)‐Selective Electrochemical Sensor Based on N,N′‐Bis(salicylidene)‐1,2‐phenylenediamine Complexes

A polyvinylchloride membrane sensor based on N,N′‐bis(salecylidene)‐1,2‐phenylenediamine (salophen) as membrane carrier was prepared and investigated as a Al³⁺‐selective electrode. The sensor exhibits a Nernstian response toward Al(III) over a wide concentration range (8.0×10^?7–3.0×10^?2 M), with a detection limit of 6.0×10^?7 M. The potentiometric response of the sensor is independent of the pH of the test solution in the pH range 3.2–4.5. The electrode possesses advantages of very fast response and high selectivity for Al³⁺ in comparison with alkali, alkaline earth and some heavy metal ions. The sensor was used as an indicator electrode, in the potentiometric titration of aluminum ion and in determination of Al³⁺ contents in drug, water and waste water samples.     

Non-Aqueous Assay System for Phenobarbital Using Biomimetic Bulk Acoustic Wave Sensor Based on a Molecularly Imprinted Polymer

ABSTRACT

A new biomimetic bulk acoustic wave (BAW) sensor based on a molecularly imprinted polymer (MIP) was fabricated and applied for the determination of phenobarbital The MIP was synthesized using phenobarbital as the template molecule and methacrylic acid as the functional monomer by the non-covalent method. In absolute ethanol, the sensor exhibited good selectivity and sensitivity. A linear relationship between 9.0×10^?8 M and 5.0×10^?5 M was revealed. The determination limit was 5.0×10^?8 M. In harsh chemical environments such as high temperature, organic solvent, bases, acids, etc., the sensor still exhibited long-time stability. Satisfactory results of real sample assay were obtained by the proposed method.     

Highly Selective and Sensitive Copper(II) Membrane Sensors Based on 6‐Methyl‐4‐(1‐phenylmethylidene)amino‐3‐thioxo‐1,2,4‐triazin‐5‐one as a New Neutral Ionophore

A new Cu(II) ion‐selective PVC membrane sensor based on 6‐methyl‐4‐(1‐phenylmethylidene)amino‐3‐thioxo‐1,2,4‐triazin‐5‐one (MATTO) as an excellent sensing material was developed. The electrode exhibits a Nernstian slope of 29.2±0.4 mV per decade over a very wide concentration range between 1.0×10^?1 and 1.0×10^?6 M, with a detection limit of 4.8×10^?7 M (30.5 ng/mL). The sensor possesses the advantages of short conditioning time, fast response time (<10 s), and especially, very good selectivity towards transition and heavy metal, and some mono, di and trivalent cations. The proposed electrode was successfully applied to the determination of copper in wastewater of copper electroplating samples and as an indicator electrode in potentiometric titration of Cu(II) ions with EDTA.