Differential Pulse Polarographic Behavior Research Articles

Differential Pulse Polarographic Behavior and Quantification of the Flucloxacillin in Pure and Pharmaceutical Dosage Forms Using a Static Mercury Drop Electrode

Differential pulse polarographic analysis (DPPA) by using static mercury drop electrode (SMDE) for quantification of flucloxacillin (FLUX) in pure and pharmaceutical dosage forms was studied. The optimum conditions for the polarographic signal were determined and a study was made of the different parameters affecting the electrochemical process. The best definition of the analytical signals was found in Britton–Robinson buffer (0.06 M) at pH 4.0 . Under the optimum conditions, liner calibration graph, Ip=f(CFLUX) was obtained in the concentration ranges of 0.1 mM (0.0494 ?g.mL-1) to 26 mM (12.8414 ?g.mL-1) at -940 to -1000 mV (versus Ag/AgCl) with relative standard deviations (RSD) did not exceed 2.4% for the concentrations of FLUX (0.0494 ?g.mL-1). Regression analysis showed a good correlation coefficient (R2=9998) between Ip and concentration over the mentioned range. The limit of detection (LOD) and the limit of quantification (LOQ) were to be 0.0040 and 0.0120 ?g.mL-1, respectively. The proposed method was validated for linearity, precision and accuracy, repeatability, sensitivity (LOD and LOQ), robustness and specificity. The developed method is applicable for the determination of FLUX in pure and different dosage forms in presence a same amount of amoxicillin (AMOX) with average recovery of 99.4 to 102.2 % and the results are in good agreement with those obtained by the HPLC reference method.

Differential Pulse Polarographic Behavior and Determination of Simvastatin in Pure and Pharmaceutical Dosage Forms Using Dropping Mercury Electrode

The differential pulse polarographic behavior and determination of simvastatin (SMV) in pure and pharmaceutical dosage forms were investigated on dropping mercury electrode (DME). The method involves the reduction behavior of SMV has been studied in different supporting electrolytes within the pH range 3–9 at DME by differential pulse polarographic analysis (DPPA). The best definition of the analytical signals was found in sodium acetate buffer at pH 7.5 at -1378 to -1384 mV (vs. Ag/AgCl). Under optimized conditions the peak current (Ip) is linear over the range 0.1256- 8.731 µg.mL-1. The DPPA was used successfully for the determination of SMV in pure form. The relative standard deviation did not exceed 4.6% for the concentration of SMV 0.12556 µg.mL-1. Regression analysis showed a good correlation coefficient (R2=0.9997) between Ip and concentration over the mentioned range. The limit of detection (LOD) and the limit of quantification (LOQ) were to be 0.015 µg.mL-1 and 0.045 µg.mL-1, respectively. The proposed method was validated for linearity, precision and accuracy, repeatability, sensitivity (LOD and LOQ), robustness and specificity with average recovery of 99.7-100.7%. The developed method is applicable for the determination of SMV in pure and different dosage forms with assay 99.0-103.0% and the results are in good agreement with those obtained by the HPLC reference method.

Differential pulse polarographic behaviour of thiazopyr herbicide and application to its determination in fruit juice and soil samples

A differential pulse polarographic method for the determination of the herbicide thiazopyr has been developed. The polarographic study of thiazopyr exhibited two well-defined cathodic peaks within the pH range of 1.0 to 8.0. The variation of pH and polarographic parameters indicated that the optimum conditions under which thiazopyr could be reduced were a pH 7.0 BR buffer solution, a reduction peak potential of −1270 mV (vs. SCE), scan rate of 5 mV s−1, pulse amplitude of 50 mV with pulse duration of 50 ms at an ambient temperature of 25 ± 3°C. The main reduction peak was characterised by cyclic voltammetry as being irreversible and diffusion-controlled. A linear relationship between the peak current and the concentration of thiazopyr was obtained in the range of 0.43–38.6 µg mL−1, with a detection limit of 0.127 µg mL−1. The proposed method was successfully applied to the determination of thiazopyr in spiked fruit juice and soil samples. The mean recoveries of the 19.8 µg g−1 and 3.96 µg mL−1 thiazopyr spiked to soil and orange juice were 20.2 ± 1.0 µg g−1 and 3.84 ± 0.12 µg mL−1, at 95% confidence level, respectively. The sufficiently good recoveries and low relative standard deviation (RSD) data confirm the high accuracy and precision of the proposed method. The interferences effects of several commonly used pesticides and inorganic species were also studied. Interfering effects were eliminated either by providing selectivity with pH, or using EDTA as complexing agent.

Polarographic and Voltammetric Assays of Sulfonamides as α‐Oxo‐γ‐Butyrolactone Arylhydrazones

2‐Acetylbutyrolactone was characterized as a novel reagent of analytical potential in polarographic and voltammetric analyses. It forms α‐oxo‐γ‐butyrolactone arylhydrazones through Japp‐Klingemann coupling reaction with primary arylamines. α‐Oxo‐γ‐butyrolactone arylhydrazones possess an electro‐active site (azomethine center) that displays a cathodic activity at the mercury electrode. The protonated azomethine center of α‐oxo‐γ‐butyrolactone arylhydrazones is reduced by 2e/2H+ reaction to the hydrazo form. The differential pulse polarographic behavior of α‐oxo‐γ‐butyrolactone arylhydrazones was investigated in aqueous media ranging from pH 2 to 10.5. In aqueous acidic solution, α‐oxo‐γ‐butyrolactone arylhydrazones were shown to adsorb on a hanging mercury drop electrode and to be amenable to determination by adsorptive stripping voltammetry. Procedures for applying the polarographic and voltammetric methods to determination of sulfadiazine and sulfamethoxazole in pharmaceutical preparations have been developed. An analogous study on sulfas‐azo derivatives of ethyl acetoacetate was also considered. Furthermore, the differential pulse voltammetric method was adopted for determination of sulfamethoxazole in spiked plasma and urine samples. The recoveries turned out to be satisfactory, showing relative standard deviations from 2.4 to 4.6%.

Differential Pulse Polarographic Behavior of Selenite and Its Application to Determination of Tin in Canned Food

The polarographic reduction of tin gives rise to an additional peak at more positive potentials than tin in the presence of selenite. It is found that when the selenite concentration exceeded the tin concentration, only one peak for tin was observed, enabling the determination of both these ions. A procedure for the direct determination of trace amounts of tin by the addition of selenite is described. It was possible to determine trace amounts of tin and selenium using this peak. Tin and selenium in a synthetic sample at 5 × 10−6 M Sn(II) and 2.5 × 10−6 M Se(IV) concentrations could be determined with -6.0% and -8.0% relative errors, respectively. This procedure was applied to canned corn, and 5.95 ± 0.54 ¼g/g tin could be determined with a 9.1% relative standard deviation.

Differential Pulse Polarographic Analysis of Chlorpyrifos Insecticide

The differential pulse polarographic (DPP) behavior of chlorpyrifos (CP) was investigated over a wide range of pH (pH 1.8–pH 10.1). CP compound displays a well-resolved cathodic reduction peak at −1.2 V (vs. Ag/AgCl) (pH 3.2). This peak probably corresponds to the reduction of the CN centre of the pyridyl moiety. The effect of solution and operational parameters on the sensitivity of the DPP peak was carefully examined in order to select the optimum conditions for determination of the CP compound. Under the optimum conditions the reduction response gives a linear calibration plot over a concentration range of 9.70 × 10−7–6.92 × 10−6 M and the detection limit was found to be 8.7 × 10−7 M. The effects of some diverse metal ions, anions and some other organophosphorus insecticides on the determination of CP compound were studied. The applicability of DPP for determination of the CP insecticide in a commercial sample as well as in some irrigation water (treated waste water and underground water) was detected.

A study of the differential pulse polarographic and stripping voltammetric behavior of the H+/K+ ATPase inhibitor SK&F 95601 and its degradation products

The differential pulse polarographic (DPP) behavior of SK&F 95601 (I) has been studied I the pH range 0 to 14. At pH ≤ 2, (I) rapidly degrades into the sulfenamide (D) and (D), which are both reduced by 2e− processes, the former being subject to strong reactant adsorption. SK&F 95601 itself is reduced in a 4e process up to pH10, and either pK2 or pK3 values, determined spectrophotometrically, are manifested polarographically at neutral pH. A pK5 value of 9.0 corresponding to the benzimidazole N-H group deprotonation is manifested polarographically with a pK′5 value of ca. 11. SK&F 95601 and its degradation produce D, degraded D, and D can all be determined by adsorptive stripping voltammetry (AdSV) with limit of detections (LODs) of 10−8 mol dm−3, except for the latter molecule with an LOD of 10−7 mol dm−3. These LODs are superior to those determined by DPP. Mixtures of these molecules can also be resotved with similar LODs. Cd2+ can be determined by ASV with a superior LOD in the presence of (I), i.e 0.08 ppb as compared to 0.57 ppb in its absence, due to chelation phenomena.

Spectrophotometric and Polarographic Studies of Di-2-pyridyl ketone 2-thienoylhydrazone.

Abstract The spectral and differential pulse polarographic (DPP) behaviour of di-2-pyridyl ketone 2-thienoylhydrazone (DPKTH) has been investigated in 30% (v/v) ethanol-buffer mixtures over a wide range of pH (2.0-12.0). The spectral bands located at 325, 276, 230 and 208 nm of the DPKTH in ethanol are assigned to the possible electronic transitions of the molecule. The spectral data at various pH values indicates that the molecule characterized by the keto = enol tautomerization and the pKa value for the enolic form of the compound is determined in aqueous ethanol and was found to be 10.6. The effect of various operational parameters on the reduction current and the mechanism of the electrode reaction of DPKTH at the DME are discussed. The main reduction peaks are attributed to the reduction of C=N centre of both the keto and enol forms. This behaviour is compared with the DPP behaviour of the other related acid hydrazone compounds. The applicability of DPP technique for the trace determination of DPKTH ...

Polarographic study of the O-chain lipopolysaccharide of Brucella melitensis after labelling as the N-malylamide derivative

A method is described for the electrochemical labelling of the antigenic O-chain polysaccharide of Brucella melitensis based on the conversion of N-formylated groups into the N-maleyl derivative. After alkaline hydrolysis of native lipopolysaccharide the O-chain polysaccharide containing free amino groups in the glycosyl units was obtained. The reaction of this biopolymer with maleic anhydride in borax buffer yielded the N-maleylamide derivative. Dialysis was used to purify the labelled polysaccharide and IR spectra used for characterization. The differential pulse polarographic behaviour of the N-maleylamide polysaccharide derivative was studied, and two polarographic peaks were obtained. The first was in the 1–10 pH range, peak intensity and peak potential depending on pH ( E P = −0.53−0.063 pH); the second appears in the 10–12 pH range and the E P potential remains practically constant at −1.51 V (vs. SCE). The analytical possibilities of the peak appearing at −1.00 V (vs. SCE) in Britton—Robinson buffer (pH = 7.4) were useful for N-maleylamide polysaccharide derivative determination in the 30–4 30 μg/ml range, with a 2.6% relative standard deviation. The polarographic process is irreversible and shows adsorption of the biopolymer onto the electrode surface. The polarographic signal remained stable during both experiments and after 3 months of cool storage of an N-maleyl-polysacch solution.

Polarographic studies of metal ion complexes of Ampicillin and Amoxycillin

A study of the direct current and differential pulse polarographic behaviour of metal complexes, especially nickel(II), of Ampicillin and Amoxycillin at the dropping mercury electrode, is described. In 1 M sodium acetate at pH 8.0, the nickel(II) complex is superior to those of cobalt(II), copper(II), and zinc(II) in providing differential pulse peaks which at −0.865 V and −0.840 V for Ampicillin and Amoxycillin respectively with respect to the Ag/AgCl, sat. KCl reference electrode at 25°C, are well separated from those of excess metal ion. Suitable working conditions of pH, ionic strength in sodium acetate supporting electrolyte, temperature and time of measurement after mixing of reactants were established for the nickel(II) systems. As the temperature of reaction and measurement is increased, the differential pulse peak near −0.850 V decreases roughly exponentially with time at ≥25°C. Tests showed that single electron reversible reduction occurs in the nickel(II) complexes. For quantitative determination by the differential pulse technique, linear calibration graphs were obtained over concentration ranges 3.0 x 10 −7 M to 3.0 x 10 −5 M and 4.0 x 10 −7 M to 2.0 x 10 −5 M for Ampicillin and Amoxycillin, respectively, with coefficients of variation from 2 to 3% for 6 determinations in the middle of the calibration ranges. Good agreement was found between results obtained by the differential pulse method and three methods from the British or US Pharmacopoeias.

Differential pulse polarography and voltammetry of di-2-pyridyl ketone benzoylhydrazone

The differential pulse polarographic (DPP) and voltammetric (DPV) behaviour of di-2-pyridyl ketone benzoylhydrazone (DPKBH), has been investigated over a wide pH range (2.1–11.5). The effect of various operational parameters on the reduction current are discussed and the mechanism of the electrode reaction is also included. Both methods DPP and DPV are applied for the analytical determination of this reagent and the detection limits are found to be 1.24 μmol/l and 0.86 μmol/l, respectively. The DPP behaviour of DPKBH in the presence of Pb(II), Cd(II) and Cu(II) is studied and the behaviour of the Cu(II)-DPKBH complex is fully investigated. The voltammetric determination of Cu(II), based on the accumulation of its complex at the hanging mercury drop electrode, is described. Statistical analysis of the calibration curve data is included.

Electroanalytical studies of chlorophylls and their determination

The differential pulse polarographic behavior and quantitation of chlorophylls have been investigated. The detection limit is 2.4 × 10−7 M. The kinetics of the photolytic reaction of chlorophylls has been explored. Some kinetic parameters of the reaction system and the possibilities of a path for the photolytic reaction of chlorophylls have been measured and established. This reaction shows zero order kinetics with a rate constant of 3.3 × 10−6 mol · dm−3 · hr−1; with the help of the Arrnhenius relation, the activation energies of this reaction were determined. The method was successfully applied to the determination of chlorophylls in toothpaste and several kinds of green leaves.

Polarographic behaviour of some organotin(IV) compounds in dimethyl sulphoxide

AbstractThe differential pulse polarographic behaviour in dimethyl sulphoxide (DMSO) of 14 organotin(IV) compounds having the general formula R3SnX (R = Me, Ph; X− = NCS−, N3−, N3−, NO3−, OH−, NCO− and OAc−) and nBu3SnCl and nBu2SnCl2 has been studied. The peak potential was found to depend markedly on the organic group and to a lesser extent on the nature of the anion X. The phenyltin compounds were reduced at lower potentials than the corresponding methyltin compounds. The data obtained could be used for trace determination of these compounds. Linear calibration curves were obtained over the concentration range of 2.8 × 10−4 to 1.9 × 10−6 mol dm−3.

Differential-pulse polarographic determination of isonicotinic acid hydrazide, and analogous hydrazides in admixture

The differential pulse polarographic behaviour of isonicotinic, nicotinic and picolinic acid hydrazides in Britton-Robinson buffers of pH 2–11 is described. The isonicotinic compound (isoniazid) is best determined at pH 5–6 at a peak potential at ca. −1.0 V (vs. Ag/AgCl). This method was applied to analysis of tablets. At pH 9, the peak potentials are −1.22, −1.34 and −1.6 V, respectively, for the three hydrazides mentioned. Calibration graphs are linear in the range 10 −6−5×10 −4 M with relative standard deviations of 1.4–2.5%.

Differential-pulse polarography applied to aromatic disulphides

The differential-pulse polarographic behaviour of p-tolyl disulphide, 3-nitrophenyl disulphide and benzyl disulphide was investigated as a function of pH and concentration. At pH 11.4, with a 50% methanol solution as the solvent, a linear relationship between peak current and concentration was obtained for each compound over at least two orders of magnitude at a static mercury drop electrode; the detection limits were 0.2 µM in each instance. The pre-wave observed in the reduction of p-tolyl disulphide and 3-nitrophenyl disulphide was shown to be caused by chemical reactions with mercury rather than by simple adsorption.

Differential pulse polarographic determination of some organotin(IV) compounds in dimethyl sulfoxide

The differential pulse polarographic behavior of two series of organotin(IV) compounds having the general formula R x SnCl 4 − x (R = Me, Ph; x = 1, 2, 3, 4) has been investigated in DMSO. The peaks obtained are recommended for the trace determination of these compounds. Linear calibration curves are obtained over the concentration range 10 −4 –10 −6 M.

Differential pulse polarography as a tool for the determination of trace levels of nicotinamide adenine dinucleotide (NAD+) and nicotinamide adenine dinucleotide phosphate (NADP+) in aqueous solution

The differential pulse polarographic behavior of NAD + and NADP + has been investigated in phosphate buffer. The peaks obtained at pH 8.0 are recommended for the trace determination of these compounds. Linear calibration curves are obtained over the concentration ranges from 2.6 × 10 −7 to 2.6 × 10 −5 M for NAD + and from 2 × 10 −6 to 4 × 10 −5 for NADP +.

Microdetermination of benzoylhydrazine and some methoxylated derivatives by using differential pulse polarography

The differential pulse polarographic behaviour of benzoylhydrazine, m-methoxy benzoyl-hydrazine, and o-methoxy benzoylhydrazine has been investigated in Britton-Robinson buffer. The peaks obtained at pH 5 are recommended for the microdetermination of these compounds. The benzoylhydrazine can be obtained with high degrees of accuracy with an experimental detection limit of 4 × 10 −6 M in simple aqueous and aqueous ethanol mixtures.

The application of 2,4,6-trinitrobenzene-1-sulphonic acid in the differential pulse polarographic determination of amines

The differential pulse polarographic behaviour of 2,4,6-trinitrophenyl (TNP) derivatives of several primary amines and amino acids was investigated in the presence of sulphite ion. All the derivatives produced a polarographic peak for their complexes with sulphite (1 × 10 −2 M) in pH 8.0 phosphate buffer (0.05 M)/0.1 M potassium chloride. The derivatives of proteins and peptides did not give such a peak. A 5-min reaction time at room temperature (or 50°C for lysine) and pH 10.5 using 1 × 10 −4 M 2,4,6-trinitrobenzene-1-sulphonic acid provides the optimal conditions for the determination of 5 × 10 −6−2.5 × 10 −5 M amines. The relative standard deviation for determining 1 × 10 −5 M glycine ( n = 5) was 1%.

Differential pulse polarographic behaviors of p-nitrosodimethylaniline: Application for microdetermination of NADH

The differential pulse polarographic behavior of p-nitrosodimethylaniline has been investigated in Britton-Robinson buffer and phosphate buffer. The peak obtained at pH 8.0 is recommended for the trace determination of this compound, with an experimental detection limit of 18 ppb (1.2 × 10 −7 M) in simple aqueous solution. The method is also applied for the indirect microdetermination of NADH. The experimental detection limit of NADH is shown to be 1.05 × 10 −6 M.