Necati Menek

VOLTAMMETRIC AND SPECTROPHOTOMETRIC STUDIES OF 2-(5-BROMO-2-PYRIDYLAZO)- 5-DIETHYLAMINO)PHENOL COPPER(II) COMPLEX

The spectrophotometric and voltammetric behavior of 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) copper(II) complex has been studied. The composition of the copper(II) complex was determined to be 1:1. The optimum conditions favoring the formation of coloured complex was studied and their stability constant determined using spectrophotometric and voltammetric techniques. Furthermore, the catalytic affect of nitrite has been investigated on the 5-Br-PADAP copper(II) complex at room temperature.

Polarographic and Voltammetric Behaviour of 2-Hydroxy-3-methoxy-5-(2-propenyl)azobenzene

Abstract The polarographic reduction of 2-hydroxy-3-methoxy-5-(2-propenyl) azobenzene in Britton Robinson Buffer with pH range 3 and 12 at room temperature has been investigated in aqueous solution of ratio 1:1. Two straight lines were obtained from the Ep-pH plots for the compound. Using the pH dependence of the polarographic and voltammetric behaviour of the azo compound the pKa value was determined to be 10.70 ± 0.02 and 11.08 ± 0.02, respectively. An electrode reaction mechanism for the azo compound has been suggested. The determination limit has been found as 1 × 10−7 M.

Polarographic and voltammetric behaviour of 2-hydroxy-3-tert-butyl-5-methylazobenzene

The polarographic and voltammetric behaviour of 2-hydroxy-3-tert-butyl-5-methylazobenzene has been studied in aqueous-ethanol mixtures of different pH using DCP and DPP polarographic and CV and SWV voltammetric methods. The reduction of the azo linkage takes place via two electrons at pH > 7, but four electrons at pH < 7 in aqueous-ethanol mixtures. It has been determined that there is a linear relationship between the current and concentration and the lowest detection limit has been found as 1 × 10−7 M (for SWV).

Syntheses, Spectral, Thermal and Electrochemical Studies of 3-Carboxylacetonehydroxamic Acid and its Iron(Ii), Cobalt(Ii), Nickel(Ii), Copper(Ii) and Zinc(Ii) Complexes

3-Carboxylacetonehydroxamic acid (CAHA) and its iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes were synthesized and characterized by elemental analysis, UV-Vis and IR spectra and magnetic susceptibility. The pK a1 and pK a2 values of the ligand in aqueous solution were found to be 6.5 ± 0.1 and 8.6 ± 0.1, which correspond to dissociation of carboxyl and hydroxamic protons, respectively. The dianion CAH acts as a tetradentate ligand through the hydroxamate and carboxylate groups and coordinates to the divalent metal ions, forming coordination polymers with a metal-to-ligand ratio of 1 : 1 in the solid state. FTIR spectra and thermal decomposition of the ligand and its metal complexes were recorded and briefly discussed. The electrochemical behavior of the complexes was investigated by square wave voltammetry and cyclic voltammetry at neutral pH. In contrast to the solid state, the iron(II) and copper(II) cations form stable complex species with a metal-to-ligand ratio of 1 : 2 in solution. The iron(II), cobalt(II) and nickel(II) complexes show two-electron irreversible reduction behavior, while the copper(II) and zinc(II) complexes undergo quasi-reversible and reversible electrode reactions, respectively. The stability constants of the complexes were determined by square wave voltammetry.

Quantitative determination of triethanolamine in cements

Abstract A new anakysis method for the quantitative determination of triethanolamine (TEA) in the aqueous phase of cements was developed. TEA was converted into the TEA-Fe3+ complex by treating it with 1M NaOH and 10% Fe3+ solutions. This method was based on the determination of the TEA-Fe3+ complex by polarographic techniques. The TEA content in the aqueous phase of the tricalcium aluminate-gypsum system was analysed using the analysis method and the amount of TEA adsorbed was found to be ≈1.5mg per g of the solid phase.

Analysis of triethanolamine in white cement pastes by voltammetric methods

Triethanolamine (TEA) in cement paste has been analysed by square wave voltammetric technique. The technique is sensitive for the quantitative determination of small amounts of TEA. The percentage of the adsorbed TEA is very dependent upon the original TEA content of the cement sample. The adsorption reached a saturation level after 12 hours of hydration and remained almost invariant at longer times.

Electrochemical characterization of luminol and its determination in real samples

The electrochemical behavior of luminol, an important molecule in forensic science, was studied in Britton–Robinson buffer solution (pH 2–pH 13) at a glassy carbon electrode using cyclic voltammetry and differential pulse voltammetry techniques. Luminol showed a well-defined and irreversible oxidation peak at 0.33 V (vs. Ag/AgCl) in 0.05 mol L−1 Britton–Robinson buffer solution at pH 12. The electrooxidation process of luminol was adsorption-controlled and irreversible over the pH range studied (2.0–13). The differential pulse voltammetric determination of luminol was carried out. Under optimal conditions, the glassy carbon electrode displayed a linear response over the range from 1.8 × 10−8 to 4.5 × 10−4 mol L−1 luminol concentration, and statistical data were evaluated. A commercially available real sample that contained luminol was analyzed according to this method. The luminol percentage of the sample was obtained as 21.2 (±0.4)%.