Copper-selective Electrode Research Articles

A semiconductor sensor based on indium antimonide for the potentiometric analysis of soils from the Chinarev oil and gas field

The ion−salt composition of soils from the Chinarev oil and gas field (West Kazakhstan Region) was studied. A semiconductor sensor based on indium antimonide (InSb) and classical ion-selective electrodes were used to analyze soil extracts. Comparative results of determinations of pH, HCO3- Cl–, and SO42- in soil samples with a semiconductor InSb-electrode and with glass, chloride-selective, and copper-selective electrodes are presented. The use of a single semiconductor sensor for the determination of four components in a soil extract allowed us to reduce the duration of analysis and to unify the determination. Based on the results obtained, the salt composition of soils from the studied field was estimated.

Rapid determination of trace level copper in tea infusion samples by solid contact ion selective electrode

A new solid contact copper selective electrode with a poly (vinyl chloride) (PVC) membrane consisting of o-xylylenebis(N,N-diisobutyldithiocarbamate) as ionophore has been prepared. The main novelties of constructed ion selective electrode concept are the enhanced robustness, cheapness, and fastness due to the use of solid contacts. The electrode exhibits a rapid (< 10 seconds) and near-Nernstian response to Cu2+ activity from 10−1 to 10−6 mol/L at the pH range of 4.0–6.0. No serious interference from common ions was found. The electrode characterizes by high potential stability, reproducibility, and full repeatability. The electrode was used as an indicator electrode in potentiometric titration of Cu(II) ions with EDTA and for the direct assay of tea infusion samples by means of the calibration graph technique. The results compared favorably with those obtained by the atomic absorption spectroscopy (AAS).

Microneedle Copper (II) Selective Electrode based on Polypyrrole Doped with 8-Hydroxyquinoline-5-Sulfonic Acid

In the present research, a microneedle Cu (II) selective electrode based on conducting polypyrrole (PPy) doped with 8-hydroxyquinoline-5-sulfonic acid (8-HQS) is introduced. 8-HQS which has been incorporated into the polypyrrole backbone during electropolymerization acts as an active ionophore for Cu (II) ion recognition. Several relevant factors affecting the sensor performance have been investigated and optimized. The proposed electrode showed a linear response over the concentration range of 1.0 × 10−5 to 1.0 × 10−1 M with a sub-Nernstian slope of 22 ± 1 mV per decade change in Cu (II) concentration. The response time of the electrode was less than 10 s and the proposed electrode revealed good selectivity for Cu (II) over a wide variety of other ions and could be used in the pH range of 4.0–7.0. The electrode was successfully employed as an indicator electrode in potentiometric titration of Cu (II) ion with EDTA and also for direct determination of copper in spiked tap water and fruit juice samples. The proposed electrode presents special features such as simplicity of operation, capability of miniaturization of steel substrate, low cost, simple fabrication and suitability to be used as Cu (II) disposable electrode and for mass production.

Potentiometric detection and removal of copper using porphyrins

BackgroundCopper is an essential trace element with a great importance in industry, environment and biological systems. The great advantage of ion-selective sensors in comparison with other proposed techniques is that they are measuring the free metal ion activity which is responsible for their toxicity. Porphyrins are known to be among the best ionophores in formulation of ion-selective sensors.ResultsA symmetrically substituted meso-porphyrin, namely: 5,10,15,20-tetrakis(4-allyloxyphenyl)porphyrin (TAPP) was used in the construction of a new copper selective-sensor and was also tested for the removal of copper from waste waters. The potentiometric response characteristics (slope and selectivity) of copper-selective electrodes based on TAPP in o-nitrophenyloctylether (o-NPOE), dioctyl phtalate (DOP) and dioctyl sebacate (DOS) plasticized with poly(vinyl chloride) membranes are compared.ConclusionsThe best results were obtained for the membrane plasticized with DOP. The sensor has linear response in the range 1x10-7 – 1x10-1 M with 28.4 ± 0.4 mV/decade near-Nernstian slope towards copper ions and presents good selectivity. Due to its chelating nature, the same porphyrin was also tested for the retention of copper from synthetic copper samples, showing a maximum adsorption capacity of 280 mg/g.

Comparison of the influence of nanomaterials on response properties of copper selective electrodes

Novel Cu2+ ion selective electrode in carbon paste matrices based on incorporation of bis(2-hydroxynaphthaldehydene)-1,6-hexanediamine (BHNHDA) has been developed. The influence of variables including sodium tetraphenylborate (NaTPB), ionophore, and amount of multiwalled carbon nanotubes (MWCNT) and Nujol and effect of two new nanoparticles including gold nanoparticles loaded on activated carbon (Au-NP-AC) and zinc sulfide nanoparticles loaded on activated carbon (ZnS-NP-AC) on the electrodes response was studied and optimized. At optimum specified conditions, the proposed electrodes have appropriate advantages such as short response times and suitable reproducibility and applicability for a period of at least 1 month without any significant divergence in slope and response properties. The sensor based on impregnations of MWCNT, Au-NP-AC and ZnS-NP-AC have wide linear range of concentration (6×10−8–1.0×10−1molL−1) and detection limit of lower than 4×10−8molL−1 of Cu2+ ion. The electrodes based on incorporation of Au-NP-AC and ZnS-NP-AC have Nernstian response with slope of 29.34±1.41 and 29.78±1.23mVdecade−1 and response is independent of pH in the range of 2.0–5.0. Finally, these electrodes have been successfully applied for the determination of Cu2+ ions content in various real samples. Due to their acceptable selectivity coefficient, they are usable for accurate and successful evaluation of Cu2+ ions content in various real sample with complicated matrices.

Dithizone Modified Gold Nanoparticles Films as Solid Contact for Cu2+ Ion‐Selective Electrodes

AbstractGold nanoparticles surface modified with dithizone were applied as dedicated transducer in ion‐selective electrodes. The presence of a dithizone modified gold nanoparticle layer beneath the ion‐selective membrane enables tailoring of copper ion fluxes in all‐solid‐state copper selective potentiometric electrodes. Thus, depending on the pretreatment of the modified gold nanoparticle layer, different potentiometric responses can be obtained: from typical for systems with lowered activity of primary ions at the back side of the membrane (with super‐Nernstian slope region), through low detection limit to classical ones.

Synthesis and Application of New Porphyrin Derivatives for Preparation of Copper Selective Electrodes: Influence of Carbon Nanotube on Their Responses

The synthesis and characterization of 5-(4- benzylacrylamide)-10, 15, 20-tris(4-benzylamine)porphyrin ((BAmidBAmin)P) and poly[5-(4-benzylacrylamide)-10, 15, 20-tris(4-benzylamine)porphyrin] (P[(BAmidBAmin)P]) are reported in this paper. The techniques IR, 1 H-NMR, UV-Vis and elemental microanalysis were used to characterize the porphyrins. These new compounds were used to manufacture a new carbon paste selective electrode for the measurement of copper ions in real samples. The effects of the carriers, sodium tetraphenylborate (NaTPB), multiwalled carbon nanotube (MWCNT), and Nujol on the electrode response were studied. The optimum values for (BAmidBAmin)P electrode were obtained as follows: carbon (150 mg), NaTPB (1.8 mg ), Nujol (36 mg), carrier (7 mg), and MWCNT (15 mg); and the optimum values for P[(BAmidBAmin)P] electrode were found to be 150, 3, 30, 7, and 20 mg, respectively. At the optimal conditions, the responses of the electrodes are linear in the Cu2+ concentration of 5.0 × 10-9 - 1.0 × 10-1 mol/L for (BAmidBAmin)P electrode and 1.0 × 10-8 - 1.0 × 10-1 mol/L for P[(BAmidBAmin)P] electrode. Moreover, the Nernstian slopes for (BAmidBAmin)P and P[(BAmidBAmin)P] electrodes were 29.50 ± 1.00 and 29.84 ± 1.00 mV per decade-1, respectively. The advantages of these electrodes include a low detection limit (4 × 10-9 and 8.5× 10-9 mol/L, wide pH range (2.5-5.5), short response time (~2 s) and high lifetime (3 months) for both carriers.

Electrochemical Examination of Copper(II) Complexes with Octaazamacrocyclic Ligand and Heterocyclic Dithiocarbamate

AbstractMixed ligand dinuclear copper(II) complexes of the general formula [Cu2(Rdtc)tpmc)](ClO4)3 with octaazamacrocyclic ligand tpmc and four different heterocyclic dithiocarbamate ligands Rdtc−, as well as the complexes [Cu2(tpmc)](ClO4)4 and [Cu(tpmc)](ClO4)2⋅2H2O were studied in aqueous NaClO4 and HClO4 solutions by cyclic voltammetry on glassy carbon electrode. The electrochemical properties of the ligands and Cu(II) complexes were correlated with their electronic structure. Conductometric experiments showed different stoichiometry in complexation of tpmc with Cu2+ ions and transport of ions in acetonitrile and in aqueous media. These studies clarified the application of this macrocyclic ligand as ionophore in a PVC membrane copper(II) selective electrode and contributed elucidation of its sensor properties.

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 150:2.3:30:4mg, respectively. At the optimum conditions, the potential response is linear over the concentration range of 5.0×10−8 to 1.0×10−1molL−1 with a Nernstian slope of 29.5±1.1mV per decade of Cu2+ ion concentration. The good performance of electrode such as low detection limit of (LOD) (4×10−8molL−1), wide applicable pH range (2.5–5.5), fast response time (˂10s) and adequate shelf life (69days) 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.

Synthesis and Characterization of 1-Chloro-4-Hydroxy-9H-Thioxanthen-9-One and its Efficient Application as Neutral Carrier for Preparation of New Copper Selective Electrode

A new copper carbon paste electrode (CPE) based on 1-chloro-4-hydroxy-9H-thioxanthen-9-one has been prepared and investigated. The influence of variables including carbon paste composition, sodium tetraphenylborate (NaTPB), ionophore and Nujol on the electrode response was studied and optimized. The optimum conditions were set as following, carbon: NaTPB: Nujol: CHTX in the ratio of 77.11:0.37:22.05:0.46%. At optimum values of all variables, electrode response is linear over the 1.0 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\,\times 10 ^{-6}$</tex></formula> to 1.0 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\,\times 10 ^{-1}~{\rm mol ~L} ^{-1}$</tex></formula> with a Nernstian slope of 28.5 mV per decade of a <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\rm Cu}^{2+}$</tex></formula> ion concentration. The good performance of electrode viz. low detection limit [3.16 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\,\times 10 ^{-7}~{\rm mol~L} ^{-1}$</tex></formula> (20.2 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm ng~m~ L} ^{-1}$</tex></formula> )], wide applicable pH range (2.8–5.8), fast response time (10 s) and adequate shelf life after (3 months) indicate the utility of the proposed electrode for evaluation of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm Cu}^{2+}$</tex></formula> ion content in various analysis. The good potentiometric selectivity coefficients evaluated by the fixed interference method (FIM) indicate selective response of proposed electrode for <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\rm Cu}^{2+}$</tex></formula> ions over various interfering ions. Due to this good figure of merit, the proposed electrode could be successfully applied for the determination of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm Cu}^{2+}$</tex></formula> ions content in various real samples.

Poly(vinyl) chloride membrane copper-selective electrode based on 1-phenyl-2-(2-hydroxyphenylhydrazo)butane-1,3-dione

1-Phenyl-2-(2-hydroxyphenylhydrazo)butane-1,3-dione (H2L) was used as an effective ionophore for copper-selective poly(vinyl) chloride (PVC) membrane electrodes. Optimization of the composition of the membrane and of the conditions of the analysis was performed, and under the optimized conditions the electrode has a detection limit of 6.30×10−7M Cu(II) at pH 4.0 with response time 10s and displays a linear EMF versus log[Cu2+] response over the concentration range 2.0×10−6 to 5.0×10−3M Cu(II) with a Nernstian slope of 28.80±0.11mV/decade over the pH range of 3.0–8.0. The sensor is stable for 9 weeks and exhibits good selectivity with respect to alkali, alkali earth and transition metal ions (e.g. Na+, K+, Ba2+, Ca2+, Zn2+, Cd2+, Co2+, Mn2+, Ni2+, Fe2+, Al3+) in the 3.0–8.0 pH range. It was successfully applied for the direct determination of copper(II) in zinc, aluminum and nickel based alloys, in soils polluted by oil, and as an indicator electrode for potentiometric titration of copper ions with EDTA.

Copper(II) Selective PVC Membrane Electrodes Based on Schiff base 1,2-Bis (E-2-hydroxy benzylidene amino)anthracene-9,10-dione Complex as an Ionophore

The Schiff base 1,2-bis(E-2-hydroxy benzylidene amino)anthracene-9,10-dione has been synthesized and explored as ionophore for preparing PVC-based membrane sensors selective to the copper (<TEX>$Cu^{2+}$</TEX>) ion. Potentiometric investigations indicate high affinity of these receptors for copper ion. The best performance was shown by the membrane of composition (w/w) of ionophore: 1 mg, PVC: 33 mg, DOP: 66 mg and KTpClPB as additive were added 50 mol % relative to the ionophore in 1 ml THF. The proposed sensor's detection limit is <TEX>$2.8{\times}10^{-7}$</TEX> M over pH 5 at room temperature (Nernstian slope 31.76 mV/dec.) with a response time of 15 seconds and showed good selectivity to copper ion over a number of interfering cations.

High-Temperature Potentiometry: Modulated Response of Ion-Selective Electrodes During Heat Pulses

The concept of locally heated polymeric membrane potentiometric sensors is introduced here for the first time. This is accomplished in an all solid state sensor configuration, utilizing poly(3-octylthiophene) as the intermediate layer between the ion-selective membrane and underlying substrate that integrates the heating circuitry. Temperature pulse potentiometry (TPP) gives convenient peak-shaped analytical signals and affords an additional dimension with these sensors. Numerous advances are envisioned that will benefit the field. The heating step is shown to give an increase in the slope of the copper-selective electrode from 31 to 43 mV per 10-fold activity change, with a reproducibility of the heated potential pulses of 1% at 10 microM copper levels and a potential drift of 0.2 mV/h. Importantly, the magnitude of the potential pulse upon heating the electrode changes as a function of the copper activity, suggesting an attractive way for differential measurement of these devices. The heat pulse is also shown to decrease the detection limit by half an order of magnitude.

Humic Acids Copper Binding Following Their Photochemical Alteration by Simulated Solar Light

Humic substances exposed to solar light play the role of photosensitizers in aquatic photochemical processes, generating free radicals during UV and visible light irradiation. During irradiation, high molecular weight structures are destroyed and low molecular weight constituents are formed. Alterations of the humic acids metal binding capacity due to their photochemical alterations occur. The present work reports controlled laboratory experimental results on the binding of copper by a certified purified peat humic acid (PPHA) before and after irradiation in a laboratory scale photoreactor. A reference curve of copper binding by photochemically unaltered humic acid was experimentally determined as a function of solution pH by potentiometric titrations. The experimental data series correspond to a pH range from 3 to 8.5, necessary for the simultaneous consideration of complexation and metal species solubility contribution in the obtained results. From the experimental results, it was apparent that copper is strongly bound by humic acid even at the acidic range of pH where the percentage of copper bound reached 60 and 95% at pH values of 3.5 and 5.5, respectively. During 12 and 20 days of irradiation experiments, humic acid photoalteration was experimentally monitored by a size exclusion chromatography system (HPLC-SEC). From the potentiometric titrations of the irradiated humic acid solutions by a copper selective electrode, it was apparent that the copper binding capacity of photoaltered humic acid solutions was significantly reduced for pH values up to 6.

8-Hydroxyquinoline based neutral tripodal ionophore as a copper (II) selective electrode and the effect of remote substitutents on electrode properties

New PVC membrane ion selective electrodes based on 1,3,5-Tris(8-quinolinoxymethyl)-2,4,6-trimethylbenzene (MO8HQ) are reported. The basic sensing material belongs to the group of tripodal ionophores. Also their derivatives prepared by placing suitable substitutents at fifth position of 8-oxine moiety, i.e, 1,3,5-Tris(5-chloro-8-quinolinoxymethyl)-2,4,6-trimethylbenzene (5CHQ), 1,3,5-Tris(5-benzoyl-8-quinolinoxymethyl)-2,4,6-trimethylbenzene (5BHQ) and 1,3,5-Tris[(5-phenylhydroxymethylene)-8-quinolinoxymethyl]-2,4,6-trimethylbenzene (HYD-8HQ) ionophores have also been used to make copper-selective membrane electrodes. Among all the four electrodes, MO8HQ and HYD-8HQ ionophores based electrodes show excellent response towards Cu (II) ions. The electrodes having composition 33% PVC, 4% MO8HQ and 63% dibutyl phthalate (DBP) and 33% PVC, 6% HYD-8HQ, 63% dibutyl phthalate (DBP) exhibit a good Nernstian response to Cu (II) ions in the range of 1.0 × 10 −6 to 1 × 10 −1 M. The electrode shows a reasonably fast response time of 15 s. The effect of pH and electrode response is also reported. It shows good selectivity for Cu (II) ions in comparison to heavy metal ions, transition metal ions and for alkali and alkaline earth metal ions. The electrode response and selectivity remains unchanged for at least 5 months. The electrode can be used as an indicator electrode in the potentiometric titration of Cu (II) ions with EDTA.

New membrane for copper-selective electrode incorporating a new thiophosphoril-containing macrocycle as neutral carrier

The new macrocycles 4-phenyl-11-(1-oxodecyl)-1,7-dithia-11-aza-4-phosphacyclotetradecane (III) and 4-phenyl-4-sulfide-11-(1-oxodecyl)-1,7-dithia-11-aza-4-phosphacyclotetradecane (IV) have been synthesised and characterised. Through their use as ionophore in an all-solid state poly(vinylchloride) matrix membrane electrode, the ability of IV as cation receptor has been studied. The electrode exhibits a Nernstian response towards copper (II) ions with a cationic slope of 30.7 ± 1.7 mV per decade, over the concentration range 3.0 × 10 − 6 to 1.0 × 10 − 2 M and the potential response remains almost unchanged over the pH range 3.9–6.4. The electrode can be used for at least seven months without a considerable alteration in its potential.

A copper-selective electrode based on bis(acetylacetone)propylenediimine

The potentiometric response characteristics of Cu 2+-selective electrodes based on bis(acetylacetone)propylenediimine ( I) combined with anion localizing agent (sodium tetraphenyl borate (NaTPB)) and solvent mediators (dibutyl butyl phosphonate (DBBP), tri- n-butyl phosphate (TBP) and chloronaphthalene (CN)) were investigated. The best results for Cu 2+ sensing was obtained for the electrode membrane containing PVC, I, DBBP and NaTPB in composition 5:100:200:6 ( I:PVC:DBBP:NaTPB) (w/w; mg), where the electrode had a Nernstian response (30.0 mV/decade) to Cu 2+ within the concentration range 1.0 × 10 −5 to 1.0 × 10 −1 M and detection limit of 0.5 ppm. The operational pH range of the electrode was 3.3–7.0. Selectivity characteristic of the proposed electrode was also assessed by calculating K A , B Pot using fixed interference method matched potential method. The sensor has been successfully used in the potentiometric titration of copper ions with EDTA.

Method of Determining the Copper(II) Ion Content in Process Solutions

The possibility of using the method of direct potentiometry with copper-selective electrodes for determining the copper(II) ion content in process solutions in manufacture of cuprammonium fibres was investigated. The pH region of stable operation of copper-selective electrodes and a method for performing measurements in the entire pH range of the solutions was proposed. The described method can be used for determining the copper(II) ion content in the presence of the components of the process solutions in manufacture of cuprammonium fibres.

Copper-selective PVC membrane electrodes based on salens as carriers

Copper(II) selective sensors have been fabricated from polyvinyl chloride (PVC) matrix membranes containing carriers, 2,2′-[1,2-ethandiyl-bis(nitrilomethylidine)-bis] meta cresole(I),2,2′-[1,2-ethandiyl-bis(nitrilomethylidine)-bis] para cresole(II) and 2,2′-[1,2-ethandiyl-bis(nitrilomethylidine)-bis] ortho cresole(III) as ionophores, dibutyl phthalate (DBP), benzyl acetate (BA), acetophenone (AP) and o-nitrophenyl octyl ether (NPOE) as plasticizing solvent mediators and sodium tetraphenylborate (STPB) and oleic acid (OA) as additives. Best performance was exhibited by the membrane having a composition ionophore (SALEN):PVC:NPOE:OA in the ratio of 4:31:55:10 (w/w). These membranes give a linear potential response in the concentration range (1.0×10 −5 to 1.0×10 −1 M) with a Nernstian slope of 29.2±0.3, 29.7±0.3 and 28.2±0.3 mV/decade of Cu 2+ and limits of detection are 3.6×10 −6 M, 3.1×10 −6 M and 6.3×10 −6 M for salen (I), (II) and (III), respectively. It has a very short response time, less than 10 s, and can be used for at least 9 weeks without any divergence in potential. The copper (II) selective electrode exhibited very good selectivities with respect to alkali, alkali earth and some transition metal ions and could be used in a pH range 3.5–6.5. It was successfully applied for the direct determination of copper in sample of brass and a sample of Wilson’s patient’s urine. This electrode was also used as an indicator electrode in titration of Cu 2+ with EDTA.

Determination of Citrate Ions by Potentiometric Titration with a Copper-Selective Electrode in Monitoring the Production of Citric Acid

A simple and rapid procedure was developed for the potentiometric titration of citrate ions in fermented solutions from citric acid production with the use of a copper-selective electrode.