فهرست مطالب

Analytical & Bioanalytical Electrochemistry
Volume:5 Issue: 4, Aug 2013

  • تاریخ انتشار: 1392/06/20
  • تعداد عناوین: 10
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  • Jahan Bakhsh Raoof, Reza Ojani, Maryam Ebrahimi, Ezat Hamidi, Asl Pages 395-415
    A new electrochemical DNA hybridization biosensor based on carbon paste electrode (CPE) and ethyl green (EG) is described. The interaction of EG and DNA is investigated in the solution and at the surface of the electrode. The results of electrochemical and spectroscopic studies indicate electrostatic interaction mode between DNA and EG. Hybridization event between the probe and its complementary sequence is investigated by square wave voltammetry of EG accumulated on the CPE. EG displays different signals in the interaction to ssDNA and dsDNA and variation in the EG signal represents the extent of hybridization at the electrode surface. The effects of some experimental variables on the performance of the biosensor are studied and optimized conditions are suggested. The selectivity of the biosensor is studied using some noncomplementary oligonucleotides. Under optimized experimental conditions, limit of detection is calculated 2.0×10-10 M.
    Keywords: DNA Biosensor, Ethyl Green, Hybridization Detection, Square Wave Voltammetry, Electrostatic Interaction
  • A Selective Sensor for Determination of Sitagliptinphosphate in Pharmaceutical Formulation
    Safaa M. Riad, Mamdouh R. Rezk, Ghada Y. Mahmoud, Abdel, Aziz El Bayoumi Abdel Aleem Pages 416-425
    A selective electrode was developed for determination of sitagliptin using precipitation based technique with ammonium reineckate as anionic exchanger in polyvinyl chloride matrix. Linear responses of 1×10−5 to 1×10−2 M with slope of 40.9 mV/decade within pH 4-7. The percentage recovery for determination of sitagliptin by the proposed sitagliptin selective electrode was 100.06±1.15. Determination of sitagliptin in its pharmaceutical formulation by the proposed electrode revealed its applicability for its determination. The proposed method was compared with a reported one. No significantdifference for both accuracy and precision was observed. The electrode exhibit good selectivity for sitagliptin with respect to a large number of inorganic, organic cations, sugars and amino acids. The proposed electrode offers the advantages of simplicity, accuracy and applicability to turbid and colored samples. The fabricated sensor was validated according to the International Conference on Harmonization (ICH) guidelines and successfully applied for the determination of the studied drug in pure form and pharmaceutical formulation without any interference.
    Keywords: Ammonium Reineckate, Sitagliptin, Potentiometry, Poly Vinyl Chloride
  • Electrochemical Studies of Dopamine, Ascorbic Acid and Their Simultaneous Determination at a Poly (Rosaniline) Modified Carbon Paste Electrode: A Cyclic Voltammetric Study
    Jamballi G. Manjunatha, Bahaddurghatta E. Kumara Swamy, Mohammad Deraman Pages 426-438
    A sensitive and selective electrochemical method for the determination of dopamine was developed using a rosaniline polymer film modified carbon paste electrode. The rosaniline polymer film modified electrode showed excellent electrocatalytic activity towards the oxidation of dopamine (DA) in phosphate buffer solution (pH 7.0). The interference studies show that the modified electrode exhibits excellent selectivity in the presence of ascorbic acid (AA). A significant improvement in cyclic voltammetric responses to DA and AA (well-defined voltammetric peaks at potentials around 205, -43 mV for DA and AA respectively) and a prominent enhancement of voltammetric sensitivity was observed at the rosaniline polymer film modified CPE. Hence, this work provides a simple and easy approach to selective detection of dopamine in the presence of ascorbic acid.
    Keywords: Electrochemistry, Rosaniline, Electropolymerisation, Dopamine, Ascorbic Acid
  • Majid Arvand, Mohammad Dehsaraei Pages 439-454
    Uric acid (UA) is a water soluble compound which is produced from purine metabolism in human body. High or low levels of UA are symptoms of some deficiencies in human body, so finding a simple and sensitive method for determination of UA is important. A new chemically modified electrode was fabricated by gold nanoparticles (GNPs) and carbon paste electrode (CPE) for determination of UA in human urine. Gold nanoparticles-modified carbon paste electrode (GNPs/CPE) was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Some important experimental parameters such as amount of modifier, pH and scan rate (ν) effects were studied by cyclic voltammetry and the best values for analysis were chosen. To propose a mechanism for oxidation of UA on the surface of modified electrode, the number of involved electrons and protons and diffusion coefficient of UA (DUA) was calculated. Square wave voltammetry (SWV) was used as an accurate technique for quantitative measurements. A good linear relation was observed between anodic peak current (ipa) and UA concentration (CUA) in the range of 2×10–7 to 2×10–4 mol L–1, and the detection limit (DL) was obtained to be 3.9×10–8 mol L–1, that is comparable to recent studies. This paper demonstrates a novel, simple, selective and rapid sensor for determination of UA in the analytical real samples.
    Keywords: Uric Acid, Gold Nanoparticle, Modified Carbon Paste Electrode, Square Wave Voltammetry, Human Urine
  • Shashanka Rajendrachari, Bahaddureghatta E. Kumara Swamy, Sathish Reddy, Debasis Chaira Pages 455-466
    Silver nanoparticle was synthesized by using acacia melanoxylon fresh leaves extract. The obtained silver nanoparticle was characterized by using X-ray diffraction (XRD), infrared absorption spectroscopy (IR), UV-Vis absorption spectroscopy (UV-Vis) and Zeta-potential analysis. The prepared silver nanoparticle/carbon paste electrode (AgNps/CPE) exhibits diffusion-controlled process and enhanced electrochemical sensing property for the detection of uric acid in presence of dopamine at physiological pH. The antibacterial property was checked the prepared silver nanoparticle is also shows good antibacterial property.
    Keywords: Silver Nanoparticle, Dopamine, Uric Acid, Acacia Melanoxylon, Cyclic Voltammetry
  • PVC Membrane Potentiometric Sensor based on (E)-2-Acetyl-3-(butyl-amino)-N-phenyl buten-2-thioamide for Selective Determination of Iron (II)
    Malihe Ahmadian Yazdely, Mohammad Ali Taher, Somayeh Tajik Pages 467-480
    In this paper, the construction and performance characteristics of novel PVC membrane Fe(II) ion selective electrodes based on (E)-2-acetyl-3-(butyl amino)-N-phenyl buten-2-thioamide is described. The electrode exhibits linear responses with Nernstian slope of 30.0±0.2 mVdecade−1 of activity within the Fe(II) ion concentration range of 3.5×10−7 to 1.2×10−2 M. This sensor is applicable in a pH range of 5.0-7.0. The lower detection limit is 1.6×10−7 M. It has a response time less than 10 s and can be used practically for a period of at least 2 months without any measurable divergence in results. The isothermal temperature coefficient of the sensor was assessed 1.24×10−3 V/oC. The electrode showed excellent selectivity towards Fe(II) ion over a wide range of alkali, alkaline earth, and transition metals ions. It was successfully applied for the direct determination of Fe(II) ions in real samples. Keywords- Ion-Selective Electrode, Fe(II) Determination, PVC Membrane, Potentiometry, (E)-2-Acetyl-3-(butyl amino)-N-phenyl buten-2-thioamide
  • Leila Hajiaghababaei, Amir Sharafi, Saeed Suzangarzadeh, Farnoush Faridbod Pages 481-493
    In this study, a Hg2+ potentiometric membrane sensor was prepared based on the highly selective complexation between 4-(benzylidene amino)-3,4-dihydro-6-methyl-3- thioxo-1,2,4-triazin-5(2H)one as ionophore and Hg2+ ion. The electrode exhibits a Nernstian response for Hg2+ over a concentration range (1.0×10-2 to 1.0×10-6 M) with a slope of29.06±0.4 mV per decade. The limit of detection of the sensor is 6.0×10-7 M. The sensor has a relatively fast response time (~10 s) and a useful working pH range of 3.5–6.5. Interference of some cations was also evaluated. It was used as an indicator electrode in potentiometric titration of Hg2+ ion with EDTA and in direct determination of Hg2+ in water and wastewater samples. The results indicate that this electrode is sensitive for determination of Hg2+ ion.
    Keywords: Hg2+, 4, (Benzylidene Amino), 3, 4, dihydro, 6, methyl, 3, thioxo, 1, 2, 4, triazin, 5(2H)one, Potentiometric Membrane Sensor
  • Safaa M. Riad, Nadia M. Mostafa Pages 494-505
    Two different sets of baclofen sensors were developed for its potentiometric determination in pharmaceutical preparations, based on the fact that baclofen behaves ascation in acidic medium and anion in basic medium (pK1=9.62 and pK2=3.87;respectively). Six baclofen- selective electrodes were investigated using precipitation based technique with either sodium tetraphenyl borate as an anionic exchanger or 1, 10-ortho-phenanthrolineferrous as a cationic exchanger; respectively upon using polyvinyl chloride (PVC) matrix and dioctylsebacate (DOS) as a plasticizer. The resultant sensors have different forms, either as membrane electrodes (sensors I&IV), coated wire electrodes (sensors II&V) or as microsized graphite electrodes (sensors III&VI). Linear responses of 10-6–10-2 M with slopes of 43.05, 43.11, and 43.05 mv/decade within pH range 4-6 were obtained for sensors I, II and III. On The other hand, Linear responses of 10-7–10-3 M with slopes of 55.90, 57.13 and 57.37 mV/decade within pH 6-8 range were obtained for sensors IV, V and VI; respectively.All these sensors were prepared and fully characterized in terms of composition, life span, usable pH range, response time and temperature. The sensors show good selectivity to the drug in presence of a variety of inorganic and organic interferent substances. The proposed procedures were compared to the USP pharmacopoeial method and showed no significant difference. The proposed sensors displayed useful analytical characteristics for the potentiometric determination of baclofen in pure form and in pharmaceutical preparations.
    Keywords: Baclofen, Selective Electrodes, Sodium Tetraphenyl Borate, 1, 10, ortho, Phenanthroline, Ferrous, Polyvinyl Chloride (PVC)
  • Mohadese Rastgoo, Deylami, Mehran Javanbakht, Mehdi Ghaemi, Hamid Omidvar, Hossein Ghafarian Pages 506-516
    A controllable synthesis of flower-like lithium iron phosphate LiFePO4 (LFP) was obtained via a two-stage heating during hydrothermal process. In the first stage, the temperature was held at 105 °C (LFP1), 120 °C (LFP2), 150 °C (LFP3) and 190 °C (LFP4) for 5 h. In the final stage, the temperature was held constant at 400 °C under H2/N2 atmosphere for 4 h. To increase the electrochemical reversibility and electronic conductivity, LFP is treated with polyethylene glycol (PEG) as the templating agent and carbon sources forthe as-prepared materials. This is to obtain a modified LFP cathode with optimum electricalcontact between the electroactive materials and the carbon-filled electrode matrix which is found to be effective in terms of raising the electrochemical performance of the Li-ionbatteries. Results show that as the first-stage temperature increased, the correspondingelectrochemical performance of the resulting sample has been increased up to a temperature of 150 °C. Galvanostatic charge-discharge test indicates that flower-like LiFePO4/C composite, LFP3, exhibits initial discharge capacity of 118 mAh g-1 at 0.1C rates. The performance improvement was attributed to a reduction of the thickness and particle size of the flower-like LiFePO4 particles. Results of X-ray diffraction (XRD) revealed that the structure of the latter represents phase of the ordered olivine structure without any impurities. Cyclic voltammetry indicates that the improvement in redox cycling could be attributed to an increase of the electrochemical active surface area (ECSA) and the related increase in microporosity as evidenced by SEM analysis.
    Keywords: Lithium Iron Phosphate (LiFePO4), Hydrothermal Synthesis, Polyethylene Glycol, Flower, Like Morphology
  • Malihe Ahmadian Yazdely, Mohammad Ali Taher, Somayeh Tajik Pages 517-527
    In the present work, we describe the preparation of a glassy carbon electrode modified with thiourea and investigate its performance for the determination of EP in aqueous solutions. Differential pulse voltammetry (DPV) exhibits a linear dynamic range from 5.0×10-8 to 1.1×10−5 M and a detection limit of 2.3×10−8 M for EP. We also evaluate the analytical performance of the modified electrode for quantification of EP in real samples.
    Keywords: Epinephrine, Glassy Carbon Electrode, Modified Electrode