Potentiometric equilibrium measurements have been performed at (25.0 ± 0.1) °C and ionic strength I = 0.1 mol dm-3 (KNO3) for the interaction of glycine (aminoethanoic acid), serine (2-amino-3-hydroxypropanoic acid), methionine (2-amino-4-(methylthio)butanoic acid), aspartic acid (aminobutanedioic acid), glutamic acid (2-aminopropanedioic acid), and histidine (α-amino-1H-imidazole-4-propanoic acid) and Cu(II), Co(II), Ni(II), Mn(II), and Zn(II) with the biologically important secondary ligand zwitterionic buffers β-hydroxy-4-morpholinepropanesulfonic acid (MOPSO), 4-morpholinepropanesulfonic acid (MOPS), 3-[bis(2-hydroxyethyl)amino]-2-hydroxy-1-propanesulfonic acid (DIPSO), and 3-[N-tris(hydroxymethyl)methyl)amino]-2-hydroxypropanesulfonic acid (TAPSO) in 1:1:1 and 1:1:2 ratios, and the formation of various 1:1:1 ternary complexes and 1:1:2 quaternary complex species was inferred from the potentiometric pH titration curves. Initial estimates of the formation constants of the resulting species and the acid dissociation constants of the different amino acids and secondary ligands studied have been refined with the SUPERQUAD computer program. The order of stability of the different normal ternary complexes in the systems under investigation in terms of metal ion follows generally the trend Cu(II) > Ni(II) > Co(II) > Zn(II) > Mn(II).

Three fluoroquinolones; gatifloxacin (GAT), moxifloxacin (MOX) and sparfloxacin (SPAR) were electrochemically studied in various buffer systems at different pH values, using a glassy carbon electrode. The three fluoroquinolones were electrochemically oxidized at potential range (0.65-1.1 V) vs Ag-AgCl-KCl. The oxidation was irreversible and exhibited adsorption-controlled process behavior at all pH values and buffers studied. An electroanalytical methodology based on the adsorptive behavior of fluoroquinolones on glassy carbon electrode (GCE) and according to the linear relation between peak current and concentration using differential pulse voltammetry (DPV) method was successfully applied to the determination of the three fluoroquinolones in bulk and tablets. The proposed methods were statistically in agreement with that obtained by spectrophotometric comparison method.

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The effects of bath composition, current density and temperature on cathodic polarization, cathodic current ef®ciency of codeposition, composition and structure of Co±Cu alloys electroplated on a steel substrate from citrate baths have been studied. Addition of boric acid to citrate electrolyte increases the percentage of Co in the deposits and improves the quality of these deposits. The cathodic current ef®ciency of the baths is relatively high and increases with increases in the metal content in the bath and the current density but decreases with temperature. The composition of the deposit is controlled by the applied current density. At low current densities, Cu-rich alloys were obtained. At higher current densities, the composition of the alloys was controlled by the limiting current density of Cu codeposition. The Co content of the deposits increases with increases in the metal content in the bath and the temperature. The structure of the deposited alloys was characterized by anodic stripping and X-ray diffraction techniques. The deposited alloys consisted of a single solid solution phase with a face-centred cubic structure.