Ahmad Soleymanpour

A new carbon paste electrode for rifampicin (RIF) drug was prepared and fully characterized in terms of composition, usable pH range and temperature. The sensor is based on 2-hydroxypropyl β-cyclodextrin as a good ionophore in the carbon paste matrix. The modified electrode showed a Nernstian slope of 59.2 mV/decade over the concentration range of 3.2 × 10−8 to 2.2 × 10−4 M with a limit of detection 2.3 × 10−8 M. The electrode has a short and stable response time of 4 s. The sensor manifested advantages of simple design, low cost, wide concentration range, excellent selectivity to rifampicin, applicable as an indicator electrode and renewability. The sensor was successfully used for determination of rifampicin in tablet and blood serum samples. Temperature dependence of the sensor potential response was examined in the temperature range of 15–55 °C. The sensor showed a very low thermal coefficient within the studied temperature range. © 2018 Elsevier B.V.

A sensitive and fast ultrasound-assisted dispersive liquid-liquid microextraction procedure combined with ion mobility spectrometry has been developed for the simultaneous extraction and determination of bendiocarb and azinphos-ethyl. Experimental parameters affecting the analytical performance of the method were optimized: type and volume of extraction solvent (chloroform, 150 µL), pH (9.0), type and volume of buffer (ammonium buffer pH = 9.0, 4.5 mL) and extraction time (3.0 min). Under optimum conditions, the linearity was found to be in the range of 2–40 and 6–100 ng/mL and the limits of detection (LOD) were 1.04 and 1.31 ng/mL for bendiocarb and azinphos-ethyl, respectively. The method was successfully validated for the analysis of bendiocarb and azinphos-ethyl in different samples such as waters, soil, food and beverage samples. © 2018 Elsevier Inc.

Electrochemical characterization of functionalized carbon nanotubes (f-CNT) including carboxyl (CNT-COOH), amine (CNT-NH2) and hydroxyl (CNT-OH) functional groups were studied using differential pulse voltammetry (DPV). The current-voltage (I-V) curves were obtained from each system and the effect of f-CNT on redox interaction of horseradish peroxidase (HRP) immobilized on the electrode surface was investigated. The non-equilibrium Green's function (NEGF) combined with density functional theory (DFT) were used to study the transport properties of f-CNT. Additionally, the effect of the number of functional groups on transport properties of CNT, I-V characteristics, electronic transmission coefficients and spatial distribution of f-CNTs have been calculated and analyzed. The results showed that the carboxyl derivative has larger transmission coefficients and current value than other f-CNTs. Then, the effect of functional groups on the electron transport in heme group of HRP is discussed. Finally, the effect of a covalent bond between active site amino acids and amine functional group of CNT was investigated and discussed. © 2018 Elsevier Ltd

A simple and rapid solid phase extraction procedure using a mini-column packed with modified sulfur nanoparticles as a new, efficient and reusable sorbent has been developed for the preconcentration of carbamazepine prior to its determination by high performance liquid chromatography. This method is based on the retention of carbamazepine by modified sulfur nanoparticles which are quite efficient for fast adsorption and desorption of carbamazepine. An HPLC system including C18, 250 × 4.6 mm column, methanol-acidic water (pH = 2.6 by acetic acid) (60:40) as mobile phase and UV detector (λ = 276 nm) was used. The effects of multiple experimental conditions such as the effect of pH, type and volume of buffer, type and volume of eluent, sample and eluent flow rate, sorbent amount and interfering ions, on the analytical performance of the method were investigated. The calibration curve was linear in the range of 0.5–200 ng mL−1 and LOD of the proposed method was found to be 0.16 ng mL−1. The procedure was successfully applied for the determination of carbamazepine in pharmaceutical samples, human plasma and breast milk. © 2017 Elsevier B.V.

A novel and very sensitive potentiometric sensor with excellent electrochemical properties was fabricated for the determination of fluvoxamine. The sensor is based on the use of the PVC-membrane containing ion-association complex of fluvoxamine with reinecke salt coated on the glassy carbon electrode which was modified with polyaniline as a conductive polymeric film. The proposed sensor exhibits a Nernstian slope of 58.9 mV per decade for fluvoxamine over a wide concentration range of 1.8 × 10−7–1.3 × 10−3 M, with a low detection limit of 7.8 × 10−8 M. The sensor has a fast response time, excellent reproducibility and long life time. It can be used within the pH range of 4.0–7.5 in a long time period. The sensor possesses a high selectivity toward a large variety of inorganic and organic co-existing species. The effect of temperature on the sensor potential response was studied and the isothermal coefficient of the sensor was calculated. The sensor has a good thermal stability within the studied temperature range. The developed sensor was used as an indicator electrode in potentiometric titration of fluvoxamine with sodium tetraphenylborate. The sensor was successfully applied in the determination of fluvoxamine in pharmaceutical solution, blood serum and urine samples. © 2017 Elsevier B.V.

A Schiff base, N,N′-(3,4-dithiahexane-1,6-diyl)bis(5-methylsalicylideneimine), was synthesized and characterized by X-ray crystallography. Dimeric complexes of nickel(II), palladium(II), and vanadium(IV) were synthesized by the reactions of the Schiff base with nickel(II) acetate, palladium(II) acetate, and vanadyl acetylacetonate in 1:1 molar ratio. In all three complexes, the thiol group was deprotonated and coordinated to the metal. The X-ray structure of the Schiff base showed that in the crystalline form, the SH groups were oxidized to the corresponding disulfide. In the dimeric complexes, coordination took place through the azomethine nitrogen, enolic oxygen, and sulfur atoms. The metal-to-ligand ratio was 1:1, and molar conductance data revealed that the metal complexes were nonelectrolytes. The free Schiff base and its complexes showed photoluminescence in methanol at room temperature. The redox behavior of the compounds was studied by cyclic voltammetry in DMF, which showed both quasi-reversible and irreversible processes. The interaction of the complexes with DNA was investigated by electronic absorption spectroscopy. © 2016 Springer International Publishing.

A very convenient, sensitive and precise solid phase extraction (SPE) system was developed for enrichment and determination of ultra-trace of cadmium ion in water and plant samples. This method was based on the retention of cadmium(II) ions by l-cystine adsorbed in Y-zeolite and carry out in a packed mini-column. The retained cadmium ions then were eluted and determined by flame atomic absorption spectrometry. The scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy techniques were applied for the characterization of cystine modified zeolite (CMZ). Some experimental conditions affecting the analytical performance such as pH, eluent type, concentration of sample, eluent flow rate and also the presence of interfering ions were investigated. The calibration graph was linear within the range of 0.1-7.5 ng mL-1 and limit of detection was obtained 0.04 ng mL-1 with the preconcentration factor of 400. The relative standard deviation (RSD) was obtained 1.4%, indicating the excellent reproducibility of this method. The proposed method was successfully applied for the extraction and determination of cadmium(II) ion in black tea, cigarette's tobacco and also various water samples. © 2016 Elsevier B.V..

A potentiometric carbon paste sensor was fabricated for determination of sulfaquinoxaline (SQX) based on the use of ion-association complex of sulfaquinoxaline sodium with 2,3,5-triphenyltetrazolium chloride. The proposed sensor exhibited Nernstian slope of 58.4 ± 0.3 mV per decade for sulfaquinoxaline over a wide concentration range of 5.0 × 10- 6 to 1.0 × 10- 2 M, with a low detection limit of 3.0 × 10- 6 M. The sensor manifested advantages of fast response time, satisfactory reproducibility, long life time, high thermal stability and, most importantly, excellent selectivities for sulfaquinoxaline relative to a wide variety of common foreign inorganic cations, anions, sugars and amino acids. The sensor was successfully used for determination of sulfaquinoxaline in pharmaceutical solution, blood serum, urine and milk samples. The isothermal coefficient of the electrode was calculated by the investigation of temperature effects on the electrode potential response. © 2015 Elsevier B.V. All rights reserved.

A potentiometric carbon paste sensor was fabricated for determination of clarithromycin based on incorporation of the ion association complex of the clarithromycin-phosphotungstate. The proposed sensor exhibited a Nernstian slope of 59.2±0.3mV per decade for clarithromycin over a wide concentration range of 7.4×10-7 to 1.5×10-3M, with a low detection limit of 5.0×10-7M. The proposed sensor manifested advantages of very fast response, long life time and, most importantly, excellent selectivity for clarithromycin relative to a wide variety of common foreign inorganic cation, and also biological species. The sensor was successfully applied to determine clarithromycin in clarithromycin tablet, blood serum and urine samples. The inclusion complex formation between β-cyclodextrin and clarithromycin was studied by the proposed sensor. The influence of the temperature on the response of the sensor was investigated and the temperature coefficient of the sensor was calculated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The construction and performance characteristics of a novel potentiometric carbon paste electrode based on incorporation of the ion-association complex of the carvedilol-phosphotungstate were studied. The electrode exhibited Nernstian slope of 58.7 mV/decade to carvedilol over a wide concentration range from 3.0 × 10-7 to 1.0 × 10-3 M with low detection limit of 1.5 × 10-7 M. The proposed sensor manifested advantages of fast response, long life time, and most importantly, good selectivities for carvedilol relative to a wide variety of common foreign inorganic cations, biological species and other β-blockers. The advantages of the new sensor were compared to the characteristics of previously reported traditional liquid inner contact PVC membrane electrode. The sensor was successfully applied as an indicator electrode in potentiometric titration and potentiometric determination of carvedilol in carvedilol tablet, blood serum and urine samples. The inclusion complex formation between α- and β-cyclodextrin and carvedilol was studied potentiometrically by the proposed sensor and formation constant of the inclusion complexes were calculated. © 2014 Elsevier Ltd. All rights reserved.

A new unsymmetrical tridentate Schiff base ligand was derived from the 1:1 M condensation of ortho-vanillin with 2-mercaptoethylamine. Nickel and palladium complexes were obtained by the reaction of the tridentate Schiff base ligand with nickel(II) acetate tetrahydrate and palladium(II) acetate in 2:1 M ratio. In nickel and palladium complexes the ligand was coordinated to metals via the imine N and enolic O atoms. The S groups of Schiff bases were not coordinated to the metals and S-S coupling was occured. The complexes have been found to possess 1:2 Metal:Ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The complexes exhibited octahedral coordination geometry. The emission spectra of the ligand and its complexes were studied in methanol. Electrochemical properties of the ligand and its metal complexes were investigated in the CH3CN solvent at the 100 mV s-1 scan rate. The ligand and metal complexes showed both reversible and quasi-reversible processes at this scan rate. The Schiff base and its complexes have been characterized by IR, 1H NMR, UV/Vis, elemental analyses and conductometry. The crystal structure of nickel complex has been determined by single crystal X-ray diffraction. © 2014 Elsevier B.V. All rights reserved.

A recently new synthesized azo Schiff base was studied to characterize its ability as a cation carrier in PVC membrane solid contact electrode. The coated glassy carbon electrode (CGCE) prepared with the azo Schiff base showed excellent response characteristics to hydrogen ions. The electrode exhibited Nernstian slope of 58.8 mV/decade over a wide concentration range of H + ion from 2.0 × 10-7 to 1.8 × 10-1 M. It possessed fast response time, satisfactory reproducibility, appropriate lifetime, and most importantly, good selectivity toward H+ relative to a wide variety of other cations. The cations that usually interfere in the function of pH glass electrode such as Na+ and K+ didn't show any significant interference on the response of the proposed electrode. The effect of different non-aqueous media on the response of electrode was investigated. The electrode was applied as an indicator electrode in acid-base titration. The applicability of the electrode was tested by determination of H+ in milk as a good matrix solution and the results were compared with those obtained by the glass pH-electrode. © 2013 The Electrochemical Society.

The construction and evaluation of a novel modified carbon paste electrode with high selectivity toward oxalate ion are described. The constructed carbon paste potentiometric sensor for oxalate ion is based on the use of a zirconium salan complex as a good ionophore in the carbon paste matrix. The electrode exhibits a Nernstian slope of 29.1 mV/decade to oxalate ion over a wide concentration range from 1.5×10-6 to 3.9 ×10-2 mol L-1 with a low detection limit of 7.0×10-7 mol L-1. The electrode possesses fast response time, satisfactory reproducibility, appropriate lifetime, and most importantly, good selectivity toward C2O42- relative to a variety of common anions. The potentiometric response of the electrode is independent of the pH of the test solution in the pH range 2.5-8.0. The modified carbon paste electrode was successfully applied as an indicator electrode in potentiometric titration and potentiometric determination of oxalate ion in mineral water, blood serum and urine samples. © 2013 Elsevier B.V.

A synthesized Schiff base ligand was studied to characterize its ability as a cation carrier in a poly(vinyl chloride) (PVC) membrane coated wire electrode. The constructed coated wire electrode showed excellent response characteristics to lead(II) ions. The electrode exhibits Nerns-tian slope of 29.1 mV/decade at 20 °C over a wide concentration range of Pb 2+ ions from 1.5 × 10 -6 to 1.3 × 10 -1 M with a low detection limit of 9.0 × 10 -7 M. The proposed potentiometric sensor has the following advantages: a very fast response, high reproducibility, long lifetime, and, most importantly, good selectivities relative to a wide variety of other cations. The selectivity behavior of the proposed Pb +-selective electrode revealed a considerable improvement compared with the previously reported PVC membrane electrodes for lead(II) ions. The potentiometric response of the electrode is independent of the pH of the test solution in the pH range 3.5-7.5. The performance of the proposed electrode was investigated in partially non-aqueous media. The electrode was successfully applied to determine Pb + ions in mineral water, blood serum, and alloy samples. © 2011 Springer-Verlag.

The construction and performance characteristics of a coated graphite phenylephrine-selective electrode based on incorporation of the ion-association complex of phenylephrine-tetraphenylborate in plasticized PVC matrix was studied. The electrode exhibited a Nernstian slope of 59.0mV/decade to phenylephrine over a wide concentration range from 3.0×10-6 to 5.6×10-2M with a low detection limit of 1.5×10-6M. The proposed electrode manifested advantages of fast response, long life time and, most important, good selectivities for phenylephrine relative to a wide variety of common foreign inorganic cations, anions and also organic species. The electrode was successfully applied to determine phenylephrine in adult cold tablets, phenylephrine eye-drops and also blood serum samples. The inclusion complex formation between α- and β-cyclodextrine and phenylephrine was studied potentiometrically by the proposed electrode. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical behavior of some anthraquinone (Aq) derivatives were investigated in acetonitrile (AN), N,N-dimethyl formamide (DMF) and dimethylsulfoxide (DMSO) by cyclic voltammetry (CV), quantum mechanics and statistical methods. A reasonable correlation between the computational and experimental standard reduction potential (E°) for electron transfer was obtained. It was concluded that the first step reduction potential, E°1 in acetonitrile, increases with hydrogen bonding, aromaticity and HOMO energy and decreases with size and polarity of anthraquinone. Trend of average values for E°1 in three solvents is AN
AUTHOR KEYWORDS: Anthraquinones; Cyclic voltammetry; Quantitative structure-property relationship (QSPR); Self consistent reaction field; Solvent effect
PUBLISHER: Electrochemical Science Group

---

Soleymanpour, A., Garaili, B., Nabavizadeh, S.M. Perchlorate selective membrane electrodes based on a platinum complex (2008) Monatshefte fur Chemie, 139 (12), pp. 1439-1445.

DOI: 10.1007/s00706-008-0947-8

Three platinum(II) complexes were synthesized and studied to characterize their ability as an anion carrier in a PVC membrane electrode. The polymeric membrane electrodes (PME) and also coated glassy carbon electrodes (CGCE) prepared with one of these complexes showed excellent response characteristics to perchlorate ions. The electrodes exhibited Nernstian responses to ClO 4 - ions over a wide concentration range from 1.5 × 10-6 to 2.7 × 10-1∈ M for PME and 5.0 × 10-7 to 1.9 × 10-1∈ M for CGCE with low detection limits (9.0 × 10-7∈ M for PME and 4.0 × 10-7∈ M for CGCE). The electrodes possess fast response time, satisfactory reproducibility, appropriate lifetime and, most importantly, good selectivity toward ClO4 - relative to a variety of other common anions. The potentiometric response of the electrodes is independent of the pH of the test solution in the pH range 2.0-9.0. The proposed sensors were used in potentiometric determination of perchlorate ions in mineral water and urine samples. © 2008 Springer-Verlag.

New PVC based polymeric membrane electrodes (PME) and coated glassy carbon electrodes (CGCE) based on synthesized Schiff base complexes of Co(III); [Co(Salen)(PBu3)2]ClO4, [Co(Me 2Salen)(PBu3)2]ClO4, [Co(Salen)(PBu3)H2O]ClO4; as anion carriers for potentiometric determination of ClO4? were studied. The PME and also CGCE electrodes prepared with [Co(Me2Salen)(PBu 3)2]ClO4 showed excellent response characteristics to perchlorate ions. The electrodes exhibited Nernstian responses to ClO4? ions over a wide concentration range with low detection limits (1.0 × 10?6 mol L?1 for PME and 9.0 × 10?7 mol L?1 for CGCE). The electrodes possess fast response time, satisfactory reproducibility, appropriate lifetime and, most importantly, good selectivity toward ClO4? relative to a variety of other common inorganic anions. The potentiometric response of the electrodes is independent of the pH in the pH range 2.5-8.5. The proposed sensors were used in potentiometric determination of perchlorate ions in mineral water and urine samples. The interaction of the ionophore with perchlorate ions was shown by UV/Vis spectroscopy.

Three synthesized platinum(II) complexes, [PtR2(NN)] (R = Me, p-MeC6H4 and p-MeOC6H4; NN = 2,2′-bipyridyl), were studied to characterize their ability as an anion carrier in a PVC membrane electrode. The polymeric membrane electrodes (PME) and also coated glassy carbon electrodes (CGCE) prepared with [Pt(p-MeOC6H4)2(NN)] showed excellent response characteristics to perchlorate ions. The electrodes exhibited Nernstian responses to ClO4- ions over a wide concentration range from 5 × 10-7 to 4.0 × 10-1 M for PME and 1.5 × 10-7 to 2.7 × 10-1 M for CGCE with low detection limits (4.0 × 10-7 M for PME and 1.0 × 10-7 M for CGCE). The electrodes possess fast response time, satisfactory reproducibility, appropriate lifetime and, most importantly, good selectivity toward ClO4- relative to a variety of other common anions. The potentiometric response of the electrodes is independent of the pH of the test solution in the pH range 2.5-9.5. The proposed sensors were used in potentiometric determination of perchlorate ions in mineral water, urine samples and also samples containing interfering anions. The interaction of the ionophore with perchlorate ions was shown by UV-vis spectroscopy. © 2006 Elsevier B.V. All rights reserved.

Four Schiff base complexes of different metal ions, M = Cr(IlI), Mn(III), Fe(III), and Co(III), were studied to characterize their ability as sulfate ion carriers in carbon paste electrode (CPE). The modified CPE electrode with Schiff base complex of Cr(III), N′,N′-ethylenebis(5- hydroxysalicylideneiminato) chromium(III) Chloride, showed good response characteristics to SO4 2- ion. The proposed electrode exhibits a Nernstian slope of 28.9 ± 0.4 m V per decade for SO 4 2- ion over a wide concentration range from 1.5 × 10-6 - 4.8 × 10-2, with a detection limit of 9.0 × 10-7 M. The CPE electrode manifested advantages of relatively fast response time, suitable reproducibility and life time and, most important, good potentiometric selectivity relative to a wide variety of other common inorganic anions. The potentiometric response of the electrode is independent of the pH of the test solution in the pH range 4.0-9.0. The proposed electrode was used as an indicator electrode in potentiometric titration of sulfate with Ba2+ ion, the determination of zinc in zinc sulfate tablet and also determination of sulfate content of a mineral water sample. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.

The complexation of synthesized diamine 2,6-bis[2-(o-aminophenoxy)methyl]- 4-bromo-1-methoxybenzene with different ions was studied conductometrically. The best interaction was observed between the diamine and Be2+ ion and the formation constant of the resulting complex was evaluated. The suitability of the diamine compound as a beryllium ion carrier in a PVC membrane electrode for potentiometric determination of Be2+ ion was investigated. The prepared electrode, with optimum composition, exhibits a Nernstian response to Be2+ ion over a wide concentration range from 3.0 × 10 -6 to 7.0 × 10-2 M and a very low detection limit of 2.0 × 10-6 M. It has an appropriate response time and suitable reproducibility, and can be used for a period of at least 1 month without any measurable divergence. The potentiometric response is independent of the pH of the test solution in the range of 4.0-7.0. The proposed sensor reveals good selectivity toward Be2+ ion with respect to many alkali, alkaline earth, transition and heavy metal ions. It was applied to the determination of beryllium in tap water samples and also samples containing interfering ions. © 2005 Elsevier B.V. All rights reserved.