VOLTAMMETRIC AND CHROMATOGRAPHIC DETERMINATION OF NAPROXEN IN DRUG FORMULATION

In this work, the electrochemical oxidation of naproxen (NAP) was studied at an ultra-trace graphite electrode (UTGE). The cyclic voltammetry (CV) technique was used to determine the optimum conditions and the effect of pH on the electrochemical oxidation of NAP. Acetate buffer (pH 4.50) was selected as the support electrolyte due to obtaining the highest electronic signal increase during oxidation of NAP at UTGE. The differential pulse voltammetry (DPV) technique was performed for electrochemical determination of NAP. In the optimum conditions, the limits of detection (LOD) and quantification (LOQ) were determined to be 8.6610-8 M and 2.8810-7 M. In addition, the amount of NAP was determined in drug tablets. The recovery studies of NAP from the drug tablet were completed in order to check the accuracy and precision of the applied voltammetric method. Furthermore, the determination of NAP was performed with the high-performance liquid chromatography (HPLC) method. These two methods were compared in terms of accuracy, precision and recovery studies

Electroanalytical and HPLC Methods for the Determination of Oxcarbazepine in Spiked Human Urine and Tablet Dosage Form

In this study, the electrochemical reduction and determination of oxcarbazepine were easily realized in various buffer solutions in the pH range of 4.50 to 11.15 in real samples using glassy car-bon electrode (GCE) by cyclic voltammetric (CV) and differential pulse voltammetric (DPV) tech-niques. The influence of pH on the cathodic peak current and peak potential was investigated. Scan rate studies were also completed. The diffusion controlled nature of the peak was established. The best results for the quantitative determination of oxcarbazepine were obtained by DPV technique in Britton-Robinson (BR) buffer (pH 8.05). In this basic medium, one irreversible and sharp cathodic peak was observed. A linear calibration curve for DPV analysis was constructed in the oxcarbazepine concentration range of 8×10–6 to 1×10–4 M. Limit of detection (LOD) and limit of quantification (LOQ) were obtained as 1.65×10–6 and 5.51×10–6 M, respectively. Repeatability, reproducibility, precision and accuracy of the developed technique were checked in spiked human urine and tablet dosage forms by recovery studies and re-sults of the high performance liquid chromatography (HPLC) technique. A reduction mechanism for the electrode reaction was proposed

Antibacterial activity of crude methanolic ex-tract and its fractions of aerial parts of Anthemis tinctoria

395-397The antibacterial activity of the methanolic extract and its frac-tions of aerial parts of Anthemis tinctoria (Asteraceae) was inves-tigated against representative gram-positive Staphylococcus aureus (ATCC 25923) and Enterococcus faecalis (ATCC 29212) and gram-negative strains Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853). The activity was con-centrated mainly in the dichloromethane (DCM) and hexane fractions of crude methanolic extract. The 5 mg of DCM extract per disk produced 15-16 mm of inhibition zone against S. aureus and P. aeruginosa, however, no activity was found against E. faecalis and E. coli. The hexane fraction showed activity against S. aureus, P. aeruginosa and E. faecalis. As DCM fraction showed the highest antibacterial activity in the disk diffusion assay, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of only this fraction was determined against S. aureus and P. aeruginosa. These values were found to be in the range of 1.25 to 10 mg/ml

Electroanalytical determination of metronidazole in tablet dosage form

In this study, the electrochemical reduction and determination of metronidazole were easily realized in Britton-Robinson buffer (pH = 4.01) using UTGE by cyclic voltammetric (CV) and differential pulse voltammetric (DPV) techniques. In this acidic medium, one irreversible and sharp cathodic peak was observed. A linear calibration curve for DPV analysis was constructed in the metronidazole concentration range 3x10-6 - 9x 10-5 mol L-1. Limit of detection (LOD) and limit of quantification (LOQ) were 1.42x10-7 and 4.76x10-7 mol L-1 respectively

Synthesis, spectroscopic studies and electrochemical properties of Schiff bases derived from 2-hydroxyaldehydes and phenazopyridine hydrochloride

Novel Schiff bases (1-4) were synthesized by the reaction of 2-hydroxybenzaldehyde, 2-hydroxy-5-methoxybenzaldehyde, 2-hydroxy-5-nitrobenzaldehyde, 2-hydroxy-1-naptaldehyde with phenazopypridine hydrochloride (PAP) and their structures were elucidated by means of spectroscopic techniques. The electrochemical reduction of PAP and its Schiff bases (1-4) were carried out on glassy carbon electrode (GCE) in dimethyl sulfoxide (DMSO) using the cyclic voltammetric (CV) technique. The effect of functional groups on reduction potential of Schiff bases was investigated. A general electrochemical reduction mechanism of the compounds was also suggested

Sensitive voltammetric determination of famotidine in human urine and tablet dosage forms using ultra trace graphite electrode

In this study, direct and sensitive determination of famotidine based on its electrochemical oxidation was investigated in spiked human urine and tablet dosage forms. The electrochemical measurements were carried out in various buffer solutions in the pH range of 0.88 to 12.08 at ultra trace graphite electrode (UTGE) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The best results were obtained for the quantitative determination of famotidine by DPV technique in 0.5 mol L-1 H2SO4 solution (pH=0.30). In this strong acid medium, one irreversible anodic peak was observed. The effect of pH and scan rate on the peak current and peak potential were investigated. The diffusion-controlled nature of the peak was established. For optimum conditions described in the experimental section, a linear calibration curve for DPV analysis was constructed in the famotidine concentration range 2 x 10-6 - 9 x 10-5 mol L-1. Limit of detection (LOD) and limit of quantification (LOQ) were 3.73 x 10-7 and 1.24 x 10-6 mol L-1 at UTGE respectively. Repeatability, precision and accuracy of the developed technique were checked by recovery studies in spiked urine and tablet dosage forms

Adsorption of Selected Amino Acids at the Mercury/Aqueous Solution Interface from the Chlorate (VII) and Its Dependence on the Supporting Electrolyte Concentration

In this study, we compared the adsorption of methionine, cysteine and cystine at the mercury/chlorate (VII) interface. Changes in the surface tension with the potential of the zero charge γ z and relative surface excess Γ' of methionine, cysteine and cystine as a function of their concentration indicate that the adsorption of the studied amino acids increases in the order of methionine > cystine > cysteine. For all the systems examined, linear dependences ln[×(1–Θ)/Θ = f(Θ)] (Frumkin isotherm) and ln (Γ/c) = f(Γ') (virial isotherm) were obtained. Changes in the adsorption parameters as a function of the supporting electrolyte concentration indicate the competitive adsorption of amino acids and ClO 4 − ions and electrostatic interactions between the water dipoles and adsorbates in the double layer