Yüksel Altun

Electroanalytical Characteristics of Lercanidipine and its Voltammetric Determination in Pharmaceuticals and Human Serum on Boron-Doped Diamond Electrode

The electrooxidative behavior and determination of lercanidipine (LRC) were investigated in aqueous acetonitrile medium at a boron-doped diamond electrode using voltammetric techniques. The LRC in selected supporting electrolyte presents a well-defined anodic response at 0.944 V, studied by the proposed method. The linear response was obtained in the ranges of 4 × 10−6 to 2 × 10−4 mmol L−1 range in 0.5 mmol L−1 sulfuric acid supporting electrolyte and 1 × 10−5 to 8 × 10−5 mmol L−1 range in spiked serum sample for square wave voltammetric technique. No electroactive interferences from the excipients and endogenous substances were found in the pharmaceutical dosage form and in the biological sample, respectively.

Potentiometric studies on nickel(II), copper(II) and zinc(II) metal complexes with new schiff bases containing cyclobutane and thiazole groups in 60% dioxane-water mixture

The acid-base equilibria of Schiff bases containing cyclobutane and thiazole functional groups and their copper(II), nickel(II) and zinc(II) complexes were investigated potentiometrically in 60% dioxane-water media at 25. 0 ± 0. 1 oC and I = 0. 10 mol L-1 NaClO4. The values of the protonation constants determined in this study, logKOH, logKNH(1) and logKNH(2), are related to the protonation of the phenolate oxygen atom, the nitrogen atom on the thiazole ring and the imine nitrogen atom, respectively. The variation of the protonation constants of the Schiff bases was interpreted on the basis of structural factors. The Schiff bases form stable complexes with copper(II), nickel(II) and zinc(II) metal ions. There was not a meaningful correlation between the basicity of the Schiff bases and the stability constants of their complexes. Complex stabilities follow the trend copper(II) > nickel(II) > zinc(II), which is in agreement with the Irving-Williams series.

L Histidinin Proton Ligand Kompleks Dengelerinin Potansiyometrik Metotla İncelenmesi

In this research, proton-ligand complex equilibrium of L-histidine was investigated using a modified glass-combined pH-electrode at 25.00±0.010C, 0.1 M ionic medium and under nitrogen atmosphere by potentiometric titration method. JH parameter should be determined in addition to E0, s due to the fact the pH value at which the protonation equilibrium of the carboxylate group of histidine is lower than 2. The calculation of stoichiometric protonation constants of L-histidine has been carried out by BEST computer programme using pH (corrected pH) determined by the use of E0, s and JH parameters.