Showing papers on "Polarography published in 2014"

Electrochemical behavior and differential pulse polarographic determination of rosuvastatin in pure form and in pharmaceutical preparations using dropping mercury electrode

Abstract: Electrochemical behavior and differential pulse polarographic analysis (DPPA) of rosuvastatin (RSV) in pure form and in pharmaceutical preparations using dropping mercury electrode (DME) with di-sodium hydrogen orthophosphate buffer at pH0.5 was applied. One redaction peak was observed in the range -1081 to -1094 mV (Ep). The peak current Ip is linear over the ranges 0.0963-24.077 μg.mL-1. The DPPA has been used successfully for the determination of RSV in pure form and in pharmaceutical formulations. The relative standard deviation did not exceed 4.0% for the concentrations of RSV 0.0963 μg.mL-1. Regression analysis showed a good correlation coefficient (R2= 0.9998) between Ip and concentration over the mentioned range. The limit of detection (LOD) and the limit of quantification (LOQ) were to be 0.0125 and 0.038 μg.mL-1, respectively. The proposed method was successfully applied to the analysis of RSV in pure and pharmaceutical dosage forms with average recovery of 95.0 to 103.95%. The results obtained agree well with the contents stated on the labels.

Differential pulse polarographic behavior and determination of rosuvastatin in pure form and in pharmaceutical preparations using a static mercury drop electrode

Abstract: Objective: Objective of study was to develop a simple, precise and accurate differential pulse polarographic analysis (DPPA) of rosuvastatin (RSV) in pure form and in pharmaceutical preparations. Methods: The DPPA was applied in Na2HPO4 buffer at pH 1.5 using a static mercury drop electrode (SMDE). Results: One redaction peak was observed in the range -951 to -970 mV (Ep). The peak current Ip is linear over the ranges 9.631-1926.10 ng. mL-1. The relative standard deviation did not exceed 3.8% and regression analysis showed a good correlation coefficient (R2= 0.9999). The limit of detection (LOD) and the limit of quantification (LOQ) were to be 1.22 and 3.70 ng. mL-1, respectively. The amount of RSV in different pharmaceutical preparations was decreases with the time (2-3% after one year) and the relative decrease was more in the tablets which contain lesser amount of RSV. Conclusion: The proposed method was successfully applied to the analysis of RSV in pure and pharmaceutical dosage forms with an average recovery of 92.50 to 101.35%.

Polarographic Interaction of Nickel (II) with Ammonium Piperidine-1-Carbodithioate: Application to Environmental Samples

Abstract: This paper describes the interaction of nickel (II) with ammonium piperidine-1-carbodithioate (APC) using Direct Current (DC) polarography (DCP) & differential pulse polarography (DPP) at the Dropping Mercury Electrode (DME) in NH4Cl-NH4OH buffer medium at pH 6.0. The polarograms shows a predominant peak for nickel (II)-APC at -1.30 V vs SCE, indicating the production of catalytic hydrogen wave (CHW) due to electrostatic interactions between APC and nickel (II). The interactions were characterized with UV-visible spectrophotometer, FT-IR and cyclic voltammetric techniques. The developed method was applied successfully to determine the nickel (II) levels in leafy vegetables and biological samples with acceptable recoveries.

Voltammetric studies on mercury behavior in different aqueous solutions for further development of a warning system designed for environmental monitoring

Abstract: This article presents some results concerning the electrochemical detection of mercury in different aqueous solutions, using the following electrodes: platinum-disk electrode (PDE), carbon paste electrode (CPE) and glass carbon electrode (GCE). Using the voltammetric technique applied on the above mentioned electrodes, the experimental conditions were established in order to obtain the maximum current peaks, in terms of the best analytical characteristics for mercury analyses. The dependence equations of cathodic current intensity on the scan rate were established in the case of mercury ion discharge in each prepared solution of 0.984 mM HgCl2 in different electrolyte background: 0.1 M KCl, 0.1 M H2SO4 and 0.9 % NaCl. Among the three investigated electrodes, the carbon paste electrode presented the highest detection sensitivity toward mercury ions in the aqueous solution. It was observed that, at a low scanning rate, the pH had an insignificant influence over the current peak intensity; however, the quantification of this influence was achieved using a quadratic polynomial equation, which could prevent the errors in mercury detection in case of industrial waste stream pH changes. The calibration curves for mercury in 0.9 % NaCl solution and in the tap water respectively were carried out.

Electrode reactions of iron oxide–hydroxide colloids

Abstract: Small-sized FeO(OH) colloids stabilised by sugars, commercially available for the clinical treatment of iron deficiency, show two waves during cathodic polarographic sweeps, or two current maxima with stationary electrodes, in neutral to slightly alkaline aqueous medium. Similar signals are observed with Fe(III) in alkaline media, pH > 12, containing citrate in excess. Voltammetric and polarographic responses reveal a strong influence of fast adsorption processes on gold and mercury. Visible spontaneous accumulation was also observed on platinum. The voltammetric signal at more positive potential is caused by Fe(III)→Fe(II) reduction, while the one at more negative potential has previously been assigned to Fe(II)→Fe(0) reduction. However, the involvement of adsorption phenomena leads us to the conclusion that the second cathodic current is caused again by Fe(III)→Fe(II), of species deeper inside the particles than those causing the first wave. This is further supported by X-ray photoelectron spectra obtained after FeO(OH) particle adsorption and reduction on a gold electrode surface. The same analysis suggests that sucrose stabilising the colloid is still bound to the adsorbed material, despite dilution and rinsing.

Sensitive Determination of Nickel (II) using Catalytic Hydrogen Wave in the Presence of Dithiocarbamates at DME

Abstract: Two new ligands, ammonium 2,6-dimethylmorpholine dithiocarbamate and ammonium 3-methylpiperidine dithiocarbamate were synthesized for the determination of nickel (II) in various environmental samples. The method was based on chelation of nickel (II) with ADMM-DTC/AMP-DTC in presence of NH4OH at pH 6.4 to produce catalytic hydrogen currents at -1.30V and -1.41 V vs SCE respectively and prior detected by DC polarography at Dropping Mercury Electrode (DME). Optimized polarographic conditions were established by studying effect of pH, supporting electrolyte, ligand and metal ion concentrations and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the present method. The present technique was successfully applied for the analysis of nickel (II) in different matrices with recoveries ranging from 97.00 - 99.00% and the results obtained were comparable with the differential pulse polarography.

Device for controlling mercury drop through static mercury electrode

Abstract: The utility model discloses a device for controlling mercury drop through a static mercury electrode, belongs to detection equipment, and particularly relates to a static mercury electrode used in polarographic analysis equipment in electrochemical detections. The device for controlling the mercury drop through the static mercury electrode is characterized in that a cylindrical mercury liquid tank is arranged inside a cylindrical mercury storage container, a mercury adding opening is formed in the side wall at the upper part of the cylindrical mercury liquid tank, a raised mercury outlet is formed in the center of the bottom of the cylindrical mercury liquid tank, the other end of a mercury liquid pipeline connected with the mercury outlet is connected with a capillary tube, an injection pump and a platinum filament extraction electrode are connected to the side surface of the mercury liquid pipeline, platinum filaments of the platinum filament extraction electrode fixed on the mercury storage container through a sealant is in contact with mercury liquid in the mercury liquid pipeline, the lengths of the platinum filaments in contact with the mercury liquid cannot excess the outlet of an injection pump downwards, a mercury discharge control valve is mounted inside the mercury liquid tank, and a movable cleaning cup is arranged at the bottom of the capillary tube. After the injection pump is used for mercury pushing, a mercury drop with an accurate volume can be obtained through adjusting the stroke of the piston plunger of the injection pump according to requirements, and in addition, the working efficiency is improved.

Study of Interaction between Vitamin C and Nickel () Ion using a Polarographic Methods

Abstract: The Polarographic study of the interaction between ascorbic acid and Ni +2 was carried out at dropping mercury electrode [DME] . This study included the determination of the kinetic parameters (kfh ,n) and thermodynamic parameters such as enthalpy change (H), free energy change (G) and entropy change (S) of Ni +2 complexes with ascorbic acid in 0.1 M KCl solution over the temperature rang of (294-309)K. The electrode processes were irreversible and diffusion controlled.

A new sensitive method for the determination of trace mercury by differential pulse polarography: Application to raw salt sample

Abstract: A new indirect differential pulse polarographic (DPP) method is established for the trace determination of mercury(II). Because of its toxic effects on human health, trace determination of mercury is very important. An indirect method had to be used since no polarographic peak is observed in its direct determination. According to the standard potentials, the reaction between Sn(II) and Hg(II) was found suitable. The peak of Sn(II) at about −0.40 V is sharp, high and very reproducible, which enables the determination of low concentrations of Hg(II). For this purpose, to a known amount of Sn(II) present in the polarographic cell (acetic acid, HAc, pH 1–2), the unknown Hg(II) sample is added and the quantitative reaction takes place directly in the cell. The Hg(II) concentration is calculated simply from the decrease of the Sn(II) peak. The limit of detection (LOD) was found as 2 × 10−7 M for S/N = 3. Interferences of some common cations, such as Fe, Cd, Cu, Zn and Pb and anions have been investigated. Only Pb had an overlapping peak with Sn(II). This peak overlap was eliminated simply by working at pH 2 (HAc electrolyte), because of the shift of the Pb peak in the Ac complex to −0.7 V. This method was successfully applied to synthetic samples and raw salt sample taken from a salt lake in Turkey.

Synthesis and Electrochemical Studies of 4-{((E)-{2-hydroxy-5-((Z) substituted phenyldiazenyl) phenyl} methylidene) amino} benzenesulphonamides

Abstract: Some new 4-{[(E)-{2-hydroxy-5-[(Z) substituted phenyldiazenyl] phenyl} methylidene] amino} benzenesulfonamides were synthesized by coupling of 4-substituted phenylazo salicylaldehydes with different sulphanalamide derivatives. Electrochemical behaviour of 4-{[(E)-{2-hydroxy-5-[(Z) substituted phenyldiazenyl] phenyl} methylidene] amino} benzenesulphonamides have been studied in Britton-Robinson buffers of pH 2.5-12.0 at dropping mercury and glassy carbon electrode. All benzenesulphonamides gave 4-electron wave corresponding to the reduction of -N=Nand -C=Nbonds at mercury electrode. On the basis of differential pulse polarography, cyclic voltammetry, IR, mass and H NMR spectral studies and product identification, a reduction mechanism has been suggested.

Electrochemical behavior of nickel bis-(2,6-diisopropylphenyl)diazobutadiene-1,4 dibromide in an aprotic solvent

Abstract: The electrochemical behavior of bis-(2,6-diisopropylphenyl)diazobutadiene-1,4 and its nickel dibromide complex on dropping mercury and glassy carbon electrodes in an aprotic solvent was studied by AC polarography and cyclic voltammetry. Both the ligand and the nickel ion complex were shown to undergo electroreduction. The electrochemical reduction of nickel bis-(2,6-diisopropylphenyl)diazobutadiene-1,4 dibromide occurred stepwise and formed intermediate nickel(I) species.

Dithiocarbamates as Selective Ligands for Polarographic Study of Manganese(II) at DME

Abstract: Two new ligands, ammonium 2,6-dimethyl morpholine dithiocarbamate (ADMM- DTC) and ammonium 3-methyl piperdine dithiocarbamate (AMP-DTC) were synthesized in the laboratory. The method was based on chelation of manganese(II) with ADMM-DTC/AMP-DTC in the presence of NH4OH at pH 6.2 and 6.8 to produce catalytic hydrogen currents at -0.72 V and -0.62 V vs. SCE respectively and prior detected by D.C poarography. Optimized polarographic conditions were established by studying effect of pH, supporting electrolyte (NH4Cl), ligand and metal ion concentrations and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the present method. This technique is successfully applied for the analysis of manganese(II) in different matrices with recoveries ranging from 97 - 99% and the results obtained were comparable with the differential pulse polarography (DPP).

Electrochemical studies of metal complexes of malonyl dihydrazide

Abstract: The present article deals with the polarographic and cyclic voltammetric investigations on metal (Mn(II), Ni(II), Cu(II), Zn(II), Cd(II), Fe(III) and Co(III)) complexes with malonyl dihydrazide (MAH). The variables that influence the electrode process were extensively discussed. The sites susceptible for reduction were reported by comparing the results obtained from polarography and cyclic voltammetry.

Determination of cefazolin by oscillographic polarography as its S , S ′-dioxide

Abstract: A simple rapid method is proposed to determine cefazolin in neat substances and powders for preparing injection solutions based on the preliminary oxidation of the preparation in weak acidic media by potassium peroxomonosulfate to respective S,S′-dioxide followed by its determination by oscillographic polarography. The concentration of the title material in the cefazolin substance was found to be 96.7%, RSD = 3%, δ= 2.4% and in the powder, 97.7%, RSD = 3%, δ = 2.3%.

Electrochemical studies of certain novel N | - (benzenesulfonyl)-3-methyl-4-(2 | -substituted-aryl

Abstract: Polarographic and cyclic voltammetric reduction of N | -(benzenesulfonyl)-3-methyl-4-(2 | substituted-aryl hydrazono)-pyrazolin-5-ones was carried out in 40% (v/v) dimethylformamide in Britton-Robinson buffer solutions of pH 1.1-10.1. Thermodynamic parameters i.e. enthalpy of activation ‘∆H* p ’, heat of activation at constant volume ‘∆H* v ’ and entropy of activation ‘∆S*’ were evaluated. The reduction was found to be diffusion controlled and irreversible at all temperatures. The compound exhibits two polarographic waves in the entire pH range of study. The results obtained in polarography were compared with the results obtained in cyclic voltammetry and a mechanism for the electrode process was proposed in acidic and basic media.

Electrochemical Investigations on 2-amino-4, 6-diethyl-5-(4’- sulphonamoyl) azopyrimidines

Abstract: The electrochemical behaviour of 2-amino-4,6-diethyl-5-(4’-sulphonamoyl)azopyrimidines has been studied on the basis of differential pulse polarography (DPP) in phosphate buffer in pH-range 2.5 to 11.5 at dropping mercury electrode (DME), and glassy carbon electrode (GCE).The electro-reduction occurs in a single well-defined 2-e step at dropping mercury electrode. At Glassy carbon electrode also one 2e- cathodic peak is observed. The electrode process is diffusion controlled and irreversible in nature. On the Basis of differential pulse polarography (DPP), a reaction mechanism has been suggested.

The polarographic study of Cobalt(II)-dithiocarbamate complexes at DME

Abstract: Cobalt is a naturally occurring element in the earth’s crust. It is a very small part of our environment and very small amounts are needed for many animals and humans to stay healthy. Cobalt poisoning can occur when exposed to large amounts of cobalt. The aim of this study was to develop a facile, rapid, robust, sensitive and selective methodology for the determination of cobalt(II). Two new ligands, ammonium 2,6dimethyl morpholine dithiocarbamate (ADMM-DTC) and ammonium 3-methyl piperdine dithiocarbamate (AMP-DTC) were synthesized in the laboratory. The method was based on chelation of cobalt(II) with ADMM-DTC/AMP-DTC in presence of NH 4 OH at pH 7.2 and 8.2 to produce catalytic hydrogen currents at -1.28 V and -1.38 V vs SCE respectively and prior detected by D.C polarography. Optimized polarogaphic conditions were established by studying effect of pH, supporting electrolyte (NH 4 Cl), ligand & metal ion concentrations and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the present method. This technique is successfully applied for the analysis of cobalt(II) in different matrices with recoveries ranging from 93- 98 % and the results obtained were comparable with the differential pulse polarography (DPP).