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Analytical & Bioanalytical Electrochemistry - Volume:9 Issue: 8, Dec 2017

Analytical & Bioanalytical Electrochemistry
Volume:9 Issue: 8, Dec 2017

  • تاریخ انتشار: 1396/10/20
  • تعداد عناوین: 10
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  • Elaheh Movahedi, Alireza Rezvani Pages 956-968
    A novel nanosensor has been constructed based on nanocomplex with silver, ([Ag(dian)2]NO3, where dian is N-(4,5-diazafluoren-9-ylidene)aniline, modified graphite screen printed electrode (Ag(I)/SPE). The Ag(I) nanocomplex have been prepared by ultrasonic method and characterized structurally by elemental analysis, IR spectroscopy and 1HNMR. Moreover, as a nanosensor for the determination of norepinephrine the Ag(I)/SPE exhibited excellent electrocatalytic activity for the oxidation of norepinephrine with a faster electron-transfer rate. The prepared Ag(I)/SPE were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The DPV technique was used for the trace determination of norepinephrine. The oxidation peak currents increased linearly with concentration over the range of 1.0-300 µM, with the detection limit of 0.6 µM for norepinephrine.
    Keywords: Norepinephrine, Ag(I) nanocomplex, Graphite screen printed electrode, Voltammetry
  • Hilfi Pardi, Deswati, * Hamzar Suyani, Tri Widya Edelwis Pages 969-981
    Research on the determination of Cu, Pb, Cd, and Zn metal ions in the amount of traces simultaneously using the method of Differential Pulse Adsorptive Stripping Voltammetry with alizarin as a complexing agent (DPAdSV-AZ) was performed. This study aims to obtain the optimum conditions in determining the concentration of Cu, Pb, Cd and Zn metal ions simultaneously in the amount of traces. The optimum conditions of the DPAdSVAZ method are pH 6, AZ concentration 0.6 mM, accumulation potential -0.15 V, accumulation time 70 s. RSD for Cu, Pb, Cd and Zn are 0.22%; 0.93%; 0.39%; 0.86%, performed 10 replicates (n=10). This method was applied to tap water samples from laboratory Central Measurement Department of Chemistry, Andalas University. The concentrations of each Cu, Pb, Cd and Zn metal in the tap water sample were (5.863±13)μg/L; (0.113±32)μg/L; (18.998±6)μg/L and (121.301±22)μg/L, with AAS method obtained metal concentration of Cd and Zn is (16.000±43)μg/L and (115.200±34)μg/L, Cu, and Pb are undetectable. Recovery of each Cu, Pb, Cd and Zn metal is (98.71; 104.21; 97.60; 99.67)% and LOD metals Cu, Pb, Cd, and Zn are (0.0054; 0.0090; 0.0057, and 0.0024)μg/L. Effect of foreign ions to ion Co2 and Ni2 10 mg/L disrupt the metal ions Cd and Zn, Fe3, and Cr6 5 mg/L interfere with the metal ion Zn and K 10 mg/L interfere in Cu, Pb, Cd and Zn metals. The comparison DPAdSV-AZ method with AAS method for Cd and Zn metal the calculated t-test statistical value were less than the critical value (p=0.05) so that the two methods were not significantly different.
    Keywords: (Cu, Pb, Cd, Zn), Tap water, Alizarin, Differential pulse adsorptive stripping voltammetry
  • Ahmad Rouhollahi*, Mohammad Hamed Barzegar Khaleghi Pages 982-999
    A processable polyaniline (PANI) was prepared via reversed microemulsion polymerization using both phosphoric acid(PA)and dodecylbenzenesulfonic acid (DBSA) as dopants. By attaching this anionic surfactant to PANI chains, solubility and hence processability of PANI in organic solvents was highly increased. Hydrophobic PANI-PADBSA also demonstrated better corrosion protection efficiency in comparison to the PANI synthesized without surface active agents. Polymerization of PANI-PA-DBSA was achieved via chemical oxidation of anilinemonomers inside micelles in the presence of ammonium persulfate (APS), phosphoric acidand dodecylbenzenesulfonic acid at room temperature within one hour. PANI-PA-DBSA was characterized using FT-IR, UV-Vis and XRD techniques before being used in a protective coating composed of xylene, as solvent, and epoxy resin, as matrix. The coating was applied, using dip coating method, on carbon steel specimens. Corrosion protection performance of different coatings was investigated by electrochemical impedance spectroscopy (EIS) and DC polarization techniques. According to DC polarization tests, corrosion potential of carbon steel was shifted about 0.2 V toward more noble potentials in case of optimized PANI-PA-DBSA. EIS data also illustrated a relatively smooth surface with very high resistance which couldserve as a good protective coating due to barrier effects of epoxy resin, reversible redox properties of PANI, and hydrophobicity of PANI-PA-DBSA. Moreover, for different samples, open circuit potential (OCP) was monitored versus time; based on the monitoring results, PANI-PA-DBSA with optimized DBSA content showed relatively little changes over time, as compared to other coatings. Further, different samples had their morphologies investigated using scanning electron microscopy (SEM).
    Keywords: Polyaniline, Phosphoric acid, Dodecylbenzenesulfonic acid, Emulsion synthesis, corrosion protection, carbon steel
  • Eda Mehmeti, Dalibor M. Stankovi *, Kurt Kalcher Pages 1000-1007
    In this work a new electrochemical method will be presented for the determination of enalapril in pharmaceutical tablets using unmodified screen printed electrode (SPE). The studies were done using amperommetric detection. Enalapril provides well defined, ovalshape oxidation peak at .05 V (vs. Ag/AgCl, 3.0 M KCl) in Britton-Robinson buffer solution (BRBS) at pH 5.0. After optimization of the experimental conditions, the influence of most common interferent compounds was tested. Under optimized experimental conditions, the signals were linearly proportional to the concentration of enalapril in the range from 2.5 to 90 µM with a detection limit of 0.9 µM. Repeatability of ten replicate measurements of 5 µM enalapril was estimated to be 1.5%. Proposed method was successfully applied for the determination of the total amount of enalapril content in pharmaceutical preparations. Nevertheless, proposed method could be beneficial for the quick quantifications of enalapril in drugs using unmodified SPE electrode without any further treatment.
    Keywords: Enalapril, Pharmaceutical tablets, Screen printed electrode, Amperometry
  • Reza Zaimbashi, Hadi Beitollahi *, Masoud Torkzadeh-Mahani Pages 1008-1020
    In this study, ZnO/Al2O3 nanocomposite modified graphite screen printed electrode (ZnO/Al2O3/SPE) was fabricated for the simultaneous determination of methyldopa and hydrochlorothiazide. The modified electrode was also employed to study the electrochemical oxidation of methyldopa and hydrochlorothiazide, using cyclic voltammetry (CV), chronoamperometry and differential pulse voltammetry (DPV) as diagnostic techniques. This modified electrode shows excellent electrocatalytic activity towards the oxidation of methyldopa with a potential shift about 240 mV to a less positive potential. Differential pulse voltammetry exhibits linear dynamic ranges from 1.0×10−6 to 1.0×10−4 M and 1.0×10−7 to 1.0×10−4 M for methyldopa and hydrochlorothiazide respectively. Under optimized experimental conditions, the detection limits of methyldopa and hydrochlorothiazide were calculated as 0.5 μM and 0.08 μM respectively, at this simple construction sensor. Finally, the fabricated sensor was satisfactorily used for the simultaneous determination of methyldopa and hydrochlorothiazide in methyldopa tablets, hydrochlorothiazide tablets and urine samples.
    Keywords: Methyldopa, Hydrochlorothiazide, ZnO, Al2O3 nanocomposite, Graphite screen printed electrode
  • Volodymyr V. Tkach *, Yana G. Ivanushko, Svitlana M. Lukanova, Olena I. Aksimentyevas., Iacute, Lvio C. De Oliveira, Gen, Iacute, Lson R. Da Silva, Reza Ojani, Petro I. Yagodynets Pages 1021-1028
    The electrochemical oxidation of the pesticide isoproturon, followed by electrochemical polymerization of its product has been described from the theoretical point of view. The mathematical model, describing both processes, has been developed and analyzed. The system´s behavior is similar to that observed in the processes of gabapentine and paracetamol detection and of so called “polythiophene paradox”, and the stable steady-state is maintained easily and rapidly, being efficient either for electroanalytical, or for electrosynthetical process. The possibility of oscillatory and monotonic instabilities was also evaluated.
    Keywords: Food safety, Intoxication prevention, Isoproturon, Electrochemical sensors, Electropolymerization, Stable steady, state
  • Somayeh Rigi Ladiz, Meissam Noroozifar* Pages 1029-1043
    A novel, selective and sensitive modified graphite paste electrode (GPE) containing ferrocyanide anionic complexs (FCN) doped-Nano resin Lewatit FO36 (NRL) was designed for simultaneous determination of Uric acid (UA) and Tryptophan (Trp). The above modified electrode was investigated by various techniques such as transmission electron microscopy, Fourier transform infrared spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The electrochemical behaviour of the UA and Trp was investigated at FCNNRL/GPE by CV, differential pulse voltammetry and Chronoamperometry techniques in pH 3. Under the optimum conditions, the calibration curves were linear in the ranges of 0.4-175.2 µM and 0.5-173 µM with detection limits 10 and 30 nM, for UA and Trp, respectively. The above sensor can be successfully was used for the determination of UA and Trp with high sensitivity and accuracy in real samples.
    Keywords: Redox probe, Ferrocyanide anionic complexs doped, Nano resin Lewatit FO36, Simultaneous determination, Uric acid, Tryptophan
  • Hanan A. Merey *, Shimaa A. Atty Pages 1044-1056
    A new fabricated ion selective electrode was described for the determination ropinirole HCl by direct potentiometry in pure drug substance and in pharmaceutical formulation. The proposed sensor was fabricated using ammonium reineckate (AR) as a cationic exchanger and 2-nitrophenyl octylether as a plasticizer in a polymeric matrix of polyvinyl chloride (PVC). Nernstian response of 55.1 mV/decade was obtained by the proposed sensor over a wide RP concentration range (10–5 to 1×10–2 mol/L) in the pH range of 3–7. The proposed sensor was stable for two weeks without any change in sensitivity. The proposed electrode shows good selectivity for the analysis of RP in the presence of up to 30% of its induced alkaline degradation product and in the presence of common inorganic and organic species commonly present in pharmaceutical dosage form. Statistical comparison between the results obtained by the proposed sensor for the analysis of ropinirole HCl in dosage form and the reported one shows no significant difference with respect to accuracy and precision.
    Keywords: Ion, selective electrodes, Ammonium reineckate, Ropinirole hydrochloride
  • N.B. Ashoka, B. E. Kumara Swamy *, H. Jayadevappa Pages 1057-1069
    Present work describes the synthesized and characterization of tungsten oxide nanoparticles (WO3NPs) was prepared by using tungsten carbide (WC). The prepared material was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and infrared spectroscopy (IR). The prepared WO3NPs was used as the modifier for the preparation of carbon past electrode (WO3NPs/MCPE). The fabricated WO3NPs/MCPE exhibits an excellent electrocatalytic activity towards the dopamine (DA) in the presence of uric acid (UA) and folic acid (FA) in 0.2M phosphate buffer solution (PBS) of pH 7.4 by cyclic voltammetric (CV) and differential pulse voltammetric techniques (DPV). From the effect of scan rate, concentration and pH of the electrode phenomenon was confirmed to be adsorption-controlled process. The lower detection limit of dopamine was 0.58 µM, and the simultaneous analysis shows a good result with peak to peak separation between dopamine and other two analytes uric acid and folic acid by DPV techniques.
    Keywords: Tungsten oxide, Dopamine, Uric acid, Folic acid, Carbon paste electrode, Electrocatalytic activity
  • Taher Alizadeh*, Maedeh Akhoundian Pages 1070-1079
    A new nitrobenzene vapor chemiresistor sensor was introduced based on a nanocomposite of graphene/imprinted polymer nanoparticles/poly (methyl methacrylate). The nano-sized molecularly imprinted polymers (nano-MIP) holding the cavities compatible with nitrobenzene molecules were synthesized utilizing methacrylic acid and vinyl benzene as the functional monomers and Divinylbenzene as the cross-linker. The copolymerization reaction was fulfilled in acetonitrile via precipitation method. The nano-MIP particles were mixed with graphene to produce a chemiresistor gas sensor. The addition of poly(methyl methacrylate) in the nanocomposite resulted in better physical durability, enhanced selectivity and higher resistance against humidity effect. The response of MIP based sensor was considerably higher than that of the NIP based gas sensor. The response of the gas sensor was reversible and a relative standard error equal to 3.1% was calculated for 4 relations in the determinations. The sensor showed linear response in the concentration range of 0.10–55.0 ppm. The detection limit was calculated to be 0.04 parts per million (S/N).
    Keywords: Graphene, Nanocomposite, Imprinted polymer nanoparticles, Chemiresistor, Nitrobenzene, Gas sensor