Highly Selective and Sensitive Membrane Sensors for Copper(II) Ion Based on a New Benzo‐Substituted Macrocyclic Diamide 6,7,8,9,10‐Hexahydro‐2H‐1,13,4,7,10‐benzodioxatriazacyclopentadecine‐3,11(4H,12H)‐dione

Novel PVC membrane (PME) and coated graphite (CGE) Cu²⁺‐selective electrodes based on 5,6,7,8,9,10‐hexahydro‐2H‐1,13,4,7,10‐benzodioxatriazacyclopentadecine‐3,11(4H,12H)‐dione are prepared. The electrodes reveal a Nernstian behavior over wide Cu²⁺ ion concentration ranges (1.0×10^?7–1.0×10^?1 M for PME and 1.0×10^?8–1.0×10^?1 M for CGE) with very low limits of detection (7.8×10^?8 M for PME and 9.1×10^?9 M for CGE). The potentiometric responses are independent of the pH of the test solutions in the pH range 2.7–6.2. The proposed electrodes possess very good selectivities for Cu²⁺ over a wide variety of the cations including alkali, alkaline earth, transitions and heavy metal ions. The practical utility of the proposed electrodes have been demonstrated by their use in the study of interactions between copper ions and human growth hormone (hGH) in biological systems, potentiometric titration of copper with EDTA and determination of copper content of a sheep blood serum sample and some other real samples.     

Lanthanum-selective sensors based on 3-amino-2-mercapto-3H-quinazolin-4-one in PVC matrix

A new solvent polymeric membrane (PME) and coated graphite (CGE) electrodes based on 3-amino-2-mercapto-3H-quinazolin-4-one as a suitable carrier for La(III) ion are described. The sensors exhibited a Nernstian response for La(III) ion over a wide concentration range (3.0 × 10^?7 to 1.0 × 10^?1 M for PME and 1.0 × 10^?7 to 1.0 × 10^?1 M for CGE) with a slope of 20.1 ± 0.3 (PME) and 23.4 ± 0.4 (CGE) mV decade^?1. The lower detection limits by PME and CGE were 2.0 × 10^?7 and 7.1 × 10^?8 M, respectively. The potentiometric response of the proposed electrodes was independent of the pH of the test solution in the pH range 3.0–9.0 with a fast response time (<10 s). The applications of prepared sensors were demonstrated in the determination of lanthanum ions in spiked water sample and also utilized for indirect determination of fluoride content of two mouth wash preparation samples.     

Investigation of Silver(I) Ion Sensing Property of Ruthenium(II) Thiosemicarbazone Complex Using Coated Graphite and Polymeric Membrane Electrodes

A ruthenium(II) complex [Ru(PPh₃)₂(pytsc)₂] {Hpytsc = pyridine‐2‐carbaldehydethiosemicarbazone, (C₅H₅N)C²(H)=N³‐N²(H)‐C¹(=S)N¹H} has been used as an ion carrier for the selective determination of silver(I) ions in solution. Silver(I) ion‐selective coated graphite based (CGE) and PVC polymeric membrane based (PME) electrodes exhibit Nernstian slope for silver(I) ions over a wide concentration range from 1.0 × 10⁻¹ M to 5.0 × 10⁻⁶ M (with CGE) and 1.0 × 10⁻¹ M to 2.0 × 10⁻⁵ M (with PME). The working pH range of these electrodes has been found to be from 1.2 to 7.2 for CGE and 2.2 to 6.5 for PME. The proposed CGE sensor exhibits better analytical features like sensitivity and selectivity towards different secondary ions in comparison to the corresponding PME with no interference from mercury(II) ions . These electrodes also act as indicator electrodes in potentiometric titration and have been successfully used for the determination of silver content in solution of real samples (1 gm dissolved in 100 mL of dilute nitric acid) such as silver ornaments and thin silver foils. Silver content determined by the use of ion selective electrode was found to vary in the concentration range from 1.20 x 10⁻² M to 7.45 x 10⁻² M and results were found to be comparable with those obtained from the traditional volumetric method of analysis. It is the first report of a metal‐ligand complex used as an ion carrier in ion selective electrode, which is selective for a metal ion other than the one used in the complex.     

Polymeric membrane and coated graphite electrode based on newly synthesized tetraazamacrocyclic ligand for trace level determination of nickel ion in fruit juices and wine samples

Novel polymeric membrane electrode (PME) and coated graphite electrode (CGE) for nickel ion were prepared based on 2,9-(2-methoxyaniline)₂-4,11-Me₂-[14]-1,4,8,11-tetraene-1,5,8,12-N₄ as a suitable neutral ionophore. The addition of lipophilic anion excluder (NaTPB) and various plasticizers viz o-nitrophenyloctylether (o-NPOE), dioctylphthalate (DOP), dibutylphthalate (DBP), 1-chloronaphthalene (CN) and tri-n-butylphosphate (TBP) have found to improve the performance of the sensors. The best performance was obtained for the membrane sensor having a composition of I:NaTPB:TBP:PVC in the ratio 6:4:100:90 (w/w; mg). The electrodes exhibit Nernstian slopes for Ni²⁺ ions over wide concentration ranges of 4.6 × 10^?7–1.0 × 10^?1 M for PME and 7.7 × 10^?8–1.0 × 10^?1 M for CGE with limits of detection of 2.7 × 10^?7 M for PME and 3.7 × 10^?8 M for CGE. The response time for PME and CGE was found to be 10 and 8 s respectively. The potentiometric responses are independent of the pH of the test solution in the pH range 3.0–8.0. The proposed electrodes revealed good selectivities over a wide variety of other cations including alkali, alkaline earth, transition and heavy metal ions. The coated graphite electrode was used as an indicator electrode in the potentiometric titration of nickel ion with EDTA and in direct determination in different fruit juices and wine samples.     

Highly Selective Chromium(III) PVC‐Membrane Electrodes Based on Some Recently Synthesized Schiff's Bases

Three recently synthesized Schiff's bases were studied to characterize their ability as Cr³⁺ ion carrier in PVC‐membrane electrodes. The polymeric membrane (PME) and coated glassy carbon (CGCE) electrodes based on 2‐hydroxybenzaldehyde‐O,O′‐(1,2‐dioxetane‐1,2‐diyl) oxime (L1) exhibited Nernstian responses for Cr³⁺ ion over wide concentration ranges (1.5×10^?6–8.0×10^?3 M for PME and 4.0×10^?7–3.0×10^?3 M for CGCE) and very low limits of detection (1.0×10^?6 M for PME and 2.0×10^?7 M for CGCE). The proposed potentiometric sensors manifest advantages of relatively fast response and, most importantly, good selectivities relative to a wide variety of other cations. The selectivity behavior of the proposed Cr³⁺ ion‐selective electrodes revealed a considerable improvement compared to the best previously PVC‐membrane electrodes for chromium(III) ion. The potentiometric responses of the electrodes are independent of pH of the test solution in the pH range 3.0–6.0. The electrodes were successfully applied to determine chromium(III) in water samples.     

Potentiometric Anion Selectivity and Analytical Applications of Polymer Membrane Electrodes Based on Novel Mn(III)‐ and Mn(IV)‐Salophen Complexes

New Mn(III)‐L and Mn(IV)‐L complexes were prepared from the highly lipophilic salophen ligand (L): phenol 2,2′‐[(4,5‐dimethyl‐1,2‐phenylene)bis[(E)‐nitrilomethylidyne]]bis[4,6‐bis(1,1‐dimethylethyl). The prepared complexes were fully characterized and used for the construction of thiocyanate membrane electrodes. Optimized membrane electrodes contained 33.0 mg PVC, 66.0 mg o‐nitrophenyloctylether, 50 or 5 (mole %) tetrakis(trifluoromethyl)phenyl borate and 1 mg Mn(III)‐L (sensor 2) or Mn‐(IV)‐L (sensor 12), respectively. Such electrodes exhibited linear responses toward thiocynate in a concentration range of 10^?1–10^?5 M and detection limits of 8.3×10^?6, 8.9×10^?6 M for sensor 2 and 12, respectively. Optimized membrane electrodes exhbited high selectivty toward thiocayante compared to more lipophilic anions. The observed thiocyanate selectivity of the optimized membranes was confirmed by formation constant calculations for Mn(III)‐L and Mn(IV)‐L with SCN^?, β=10^14.1 and 10^12.5, which was measured potentiometrically using the sandwich membrane method. Furthermore, computational study using DFT calculations was performed to at DFT/B3LYP level of theory to confirm the observed selectivity data. The response times were 3 and 0.5 min for low and high concentrations. The lifetimes of the optimized electrodes were ～4–6 weeks. The analytical utility of the optimized membrane electrodes was demonstrated by the analysis of thiocyanate level in different saliva samples.     

Electrochemiluminescence Based on Solid State Tri(4,7‐diphenyl‐1,10‐phenanthroline) Ruthenium(II) Ditetrakis(4‐chlorophenyl) Borate Immobilized on Carbon Fibers

A simple method for immobilization of tri(4,7‐diphenyl‐1,10‐phenanthroline) ruthenium(II) ditetrakis(4‐chlorophenyl) borate ([Ru(dpp)₃][(4‐Clph)₄B]₂) on carbon fiber electrodes was developed. Excellent electrochemical activity and electrochemiluminescence (ECL) signal of the coated carbon fiber electrodes were observed using oxalate as the co‐reactant. In addition, the effects of pH, scan rate, nitrogen and oxygen on ECL intensity were also studied. To demonstrate the reliability, the coated carbon fiber electrodes were used as ECL detectors and very low concentration of phenol was detectable (5.0×10^?8 M).     

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 .     

Electroanalytical Studies on Cobalt(II) Ion‐Selective Sensor of Polymeric Membrane Electrode and Coated Graphite Electrode Based on N2O2 Salen Ligands

Poly(vinyl chloride)‐based membranes of salen ligands, 2‐((E)‐((1R,2S)‐2‐((E)‐5‐tert‐butyl‐2‐hydroxybenzylideneamino)cyclohexylimino)methyl)‐4‐tert‐butyl phenol (S₁) and 2‐((E)‐((1R,2S)‐2‐((E)‐3,5‐di‐tert‐butyl‐2‐hydroxybenzylideneamino)cyclohexylimino)methyl)‐4,6‐di‐tert‐butylphenol (S₂) were fabricated and explored as cobalt(II) selective electrodes. The performance of the polymeric membrane electrode (PME) and coated graphite electrode (CGE) were compared and it was observed that CGE showed a wide working concentration range of 1.1×10^?8 to 1.0×10^?1 mol L^?1 with a limit of detection of 7.0×10^?9 mol L^?1 exhibiting the Nernstian slope 29.6 mV/decade of activity in the pH range 3.0–9.0. It was used for the determination of cobalt(II) ions in water, soil, beer, pharmaceutical samples and medicinal plants and would be used as an indicator electrode in potentiometric titration with EDTA.     

1,3,4-Trisubstituted-2-azetidinone Derivatives as Novel Receptors for Bismuth(III) Ion-Selective Electrodes: Application in Pharmaceutical and Glass Samples

Abstract

Polymeric membrane electrodes (PMEs) and coated graphite electrodes (CGEs) containing 1,3,4-trisubstituted-2-azetidinone derivatives as ion carriers are reported here for bismuth(III) ion selectivity. These electrodes exhibited Nernstian response for Bi³⁺ ions over a wide concentration range (5.0 × 10^?7 M to 1.0 × 10^?1 M for CGE) with a lower detection limit of 3.98 × 10^?7 M (for CGE) and wide pH range (1.3–5.0). Compared to polymeric membrane electrode, the coated graphite electrode has shown better selectivity for Bi³⁺ ions with respect to common metal ions. Proposed electrodes have been used for the estimation of Bi³⁺ ions in pharmaceutical and glass samples.     

Iodide‐Selective Electrodes Based on Bis[N(2‐methyl‐phenyl) 4‐Nitro‐thiobenzamidato]mercury(II) and Bis[N‐phenyl 3,5‐Dinitro‐thiobenzamidato]mercury(II) Carriers

Highly selective poly(vinyl chloride) (PVC) membrane electrodes based on recently synthesized mercury complexes including Hg(Nmpntb)₂ and Hg(Npdntb)₂ as new carriers for iodide‐selective electrodes by incorporating the membrane ingredients on the surface of graphite electrodes are reported. The effect of various parameters including the membrane composition, pH and possible interfering anions were investigated on the response properties of the electrodes. Both sensors exhibited Nernstian responses toward iodide over a wide concentration range of 7×10^?7 to 0.1 M and 1×10^?6 to 0.1 M, with slopes of 59.6±0.8 and 58.9±0.9 mV per decade of iodide concentration and detection limit of 3×10^?7 M and 7×10^?7 for Hg(Npdntb)₂ and Hg(Nmpntb)₂, respectively, over a wide pH range of 3–11. The sensors have response times of ≤5 s and can be used for at least 2 months without any considerable divergence in their potential response. The proposed electrodes show good ability to discriminate iodide over several inorganic and organic anions. The electrodes were successfully applied to direct determination of iodide in synthetic mixture, waste water and drinking water and as indicator electrodes in precipitation titrations.     

Novel Potentiometric PVC‐Membrane and Coated Graphite Sensors for Lanthanum(III)

Preliminary theoretical studies revealed the selective complexation of bis (2‐mercaptoanil) diacetyl (BMDA) with La³⁺ over several alkali, alkaline earth and heavy metal ions. Thus, novel PVC‐based membrane (PBM) and coated graphite membrane (CGM) sensors for La(III) based on BMDA were prepared. The electrodes display Nernstian behavior over wide concentration ranges (i.e., 1.0×10^?5–1.0×10^?1 M for PBM and 1.0×10^?6–1.0×10^?1 M for CGM). The potential response of sensors was pH independent in the range of 4.0–8.0. The sensors possess satisfactory reproducibility, fast response time (<15 s), and specially excellent discriminating ability for La³⁺ ions with respect to most of the cations. The membrane sensor was used as an indicator electrode in potentiometric titration of lanthanum ions with EDTA. The coated graphite membrane electrode was applied in determination of fluoride ions in mouth wash preparations.     

Synthesis,metal ion complexation and first use of a thia-aza substituted macrocyclic diamide as a novel sensing material for preparation of selective and sensitive poly(vinyl chloride)-membrane potentiometric sensors for Ag+ ion

A novel thia-aza substituted macrocyclic diamide 7,10,13-triaza-1-thia-4,16-dioxa-20,24-dimethyl-2,3;17,18-dibenzo-cyclooctadecane-6,14-dione (L) was synthesized and stability of its complexes with several alkaline earth, transition and heavy metal ions were studied conductometrically in methanol solution. The resulting 1:1 Ag⁺–L complex found to be the most stable one among all cation complexes studied. The optimized structures of the ligand and its Ag⁺ complex were also investigated. Based on the preliminary results thus obtained, L was used as an excellent sensing material to prepare polymeric membrane (PME) and coated graphite (CGE) silver-selective electrodes. The electrodes revealed a Nernstian behavior over wide Ag⁺ ion concentration ranges (i.e., 2.0 × 10^?6–1.0 × 10^?2 M for PME and 5.0 × 10^?7–1.0 × 10^?2 M for CGE). The potentiometric responses were independent of pH of the test solution in the range 2.9–6.8. The electrodes possessed advantages of low resistance, relatively fast response time, long lifetimes and, especially, good selectivity relative to a wide variety of other cations. The electrodes were used, as indicator electrodes, in the potentiometric titration of silver ion and in the determination of Ag⁺ ion in waste water, photographic emulsion, radiographic and photographic films and dental amalgams.     

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.     

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.     

Design of a Vitamin B1‐Selective Electrode Based on an Ion‐Pair and Its Application to Pharmaceutical Analysis

Vitamin B₁‐selective electrodes with PVC membrane were developed that contain ion associates of vitamin B₁ with an inorganic anion, BiI₄^?, and an organic anion, brilliant yellow, as electrode‐active substances. The linearity ranges of the electrode function are 1.0×10^?5–1.0×10^?2 and 1.0×10^?4–1.0×10^?2 M, the electrode function slopes are 33.0±1.0 and 33.1±1.1 mV decade^?1, the detection limits are 5.5×10^?6 and 8.3×10^?5 M for BiI₄^? and brilliant yellow respectively. The working range of pH is 5–12. The efficiency of the use of electrodes for the vitamin B₁ content control in multivitamin pharmaceutical preparations was shown by direct potentiometry and potentiometric titration methods.     

New Macrocyclic Diamides as Neutral Ionophores for Highly Selective and Sensitive PVC‐Membrane Electrodes for Be2+ Ion

Five recently synthesized macrocyclic diamides were investigated to characterize their ability as beryllium ion carriers in potentiometric PVC‐membrane electrodes. The electrodes based on 1,15‐diaza‐3,4;12,13‐dibenzo‐5,8,11‐trioxabicyclo[13,2,2] heptadecane‐2,14‐dione exhibited a Nernstian response for Be²⁺ ion over wide concentration ranges (from 3.0×10^?6 to 3.0×10^?2 M for polymeric membrane electrode, PME, and from 5.0×10^?7 to 2.0×10^?2 M for coated glassy carbon electrode, CGCE) and very low detection limits (2.0 ×10^?6 M for PME and 4.0×10^?7 M for (CGCE). The electrodes possess low resistances, fast responses, satisfactory reproducibilities and, most importantly, good selectivities relative to a variety of other common cations. The potentiometric response of the electrodes is independent of pH of test solution in the pH range of 4.0–7.5. The proposed sensors were used to determine beryllium ion in water samples.     

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.     

Be(II) Graphite Coated Membrane Sensor Based on a Recently Synthesized Benzo‐9‐Crown‐3 Derivative

A highly sensitive and selective membrane electrode with 9‐crown‐3 derivative (CD) as ionophore, potassium tetrakis‐(p‐chlorophenyl) borate as anionic additive (KTB), acetophenone (AP) as solvent mediator was prepared and investigated as a Be(II) sensor. The best performance was observed with the membrane having the percent ratio 30% PVC: 8% CD: 6% KTB: 56% Acetophenone. The poly(vinyl chloride) PVC membrane containing 9‐crown‐3 derivative (CD) directly coated on a graphite electrode, shows a Nernstian response for Be(II) ions over a very wide concentration range (1.0×10^?1?1.0×10^?7 M) with a detection limit of 8.0×10^?8 M (ca. 0.72 ng/mL). It has a fast response time of ca. 20 s and can be used for at least 10 weeks without any major deviation in potential. The proposed sensor exhibits very good selectivity with respect to common alkali, alkaline earth, transition and heavy metal ions. The proposed sensor was used as end point indicator electrode in the titration of Be(II) ions with EDTA. It was also applied to determination of Be(II) in real sample.     

Mixed Aza‐Thioether Crowns Containing a 1,10‐Phenanthroline Sub‐Unit as Neutral Ionophores for Silver Ion

Three different recently synthesized aza‐thioether crowns containing a 1,10‐phenanthroline sub‐unit (L1–L3) and a corresponding acyclic ligand (L4) were studied to characterize their abilities as silver ion ionophores in PVC‐membrane electrodes. Novel conventional silver‐selective electrodes with internal reference solution (CONISE) and coated graphite‐solid contact electrodes (SCISE) were prepared based on one of the 15‐membered crowns containing two donating S atoms and two phenanthroline‐N atoms (L1). The electrodes reveal a Nernstian behavior over wide Ag⁺ ion concentration ranges (1.0×10^?5?1.0×10^?1 M for CONISE and 5.0×10^?8?4.0×10^?2 M for SCISE) and very low limits of detection (8.0×10^?6 M for CONISE and 3.0×10^?8 M for SCISE). The potentiometric response is independent from pH of the solution in the pH range 3.0–8.0. The electrodes manifest advantages of low resistance, very fast response and, most importantly, good selectivities relative to a wide variety of other cations. The electrodes can be used for at least 2 months (for CONISE) and 4 months for (SCISE) without any appreciable divergence in potentials. The electrodes were used as an indicator electrode in the potentiometric titration of Ag⁺ ion and in the determination of silver in photographic emulsions and in radiographic and photographic films.