Cathodic stripping voltammetry of copper, based on the accumulation and reduction of its complex with 1,lO-phenanthroline (phen), has been studied. The complex is reduced in two steps from Cul-phen and Cu"-phen to copper amalgam at potentials of -0.43 and -0.62V vs. Ag/AgCl, respectively. The reduction processes are strongly dependent on the pH of the solution, as well as on the concentration of the metal ion and ligand. The reduction mechanism of both complexes was established. The detcction limit for copper in 0.55mol/LNaC1 with 20min accumulation at 0.OV vs. Ag/AgCI, measuring the reduction peak of the Cut-phen complex at -0.43 V vs. Ag/AgCI by SWV, was found to be about 5 x 10-lomol/L. The reaction parameters were calculated by square-wave voltammetry (SWV), i.e., transfer coefficients aCu~.phen = 0.31 and N~~I I .~~~~ = 0.45, and the maximum surface concentrations rCu~.phen = (2.02 f 0.08) x lo-" mol/cm2 and ~,-"II phen = (2.83 i 0.12) x lo-'* rnol/cm2. Measurements of the copper content in natural seawater samples were performed as well.
The mechanism of synergetic adsorptive accumulation of copper(n)-phenanthroline-tributylphosphate (Cu-phen-TBP) complex at the mercury drop electrode surface has been described. The behaviour and characteristics of the CU" mixed ligand complex was studied and the relationship between the properties of square-wave response and the parameters of a charge transfer and of the excitation signal are discussed. Square-wave voltammetric response of the Cu-phen-TBP complex are analysed according to the theoretical results.
Zahvaljujući klimatskim i zemljopisnim karakteristikama južna područja Hercegovine pogodna su za uzgoj agruma. Najzastupljenija je mandarina koja se prvenstveno uzgaja na okućnicama u vidu manje ili veće skupine pojedinačnih stabala. Većih komercijalnih nasada agruma nema jer su voćari tradicionalno orijentirani drugim mediteranskim voćnim vrstama. Rasadničarska proizvodnja osigurava zdrav sadni materijal te se u Hercegovini proizvode sadnice svih vrsta agruma. U radu su prikazane najzastupljenije sorte mandarina na području Hercegovine: Zorica rana, Chahara, Ichumare, Okitsu, Kuno, Seto, Kawano Wase, Saigon, Klementina i Curafora Segentrange.
The electrochemical investigation of the chiral active compound, (4S)-4-diisopropyl-2,2'-bithiazoline (DPT), commonly used in asymmetric syntheses as well as in diastereoselective reactions, and its interaction with copper(n) ion by cathodic stripping voltammetry at a HMDE electrode, was performed. DPT reduction occurs in two steps, at potentials about -0.2 and -0.45 V (vs. Ag/AgCl), through the formation of an electrodeposited layer of DPT-Hg at the electrode surface. DPT complex with copper(i1) is reduced at about -0.36 V, through the formation of DPT-Cu deposit at the electrode surface. The reduction process of DPT-Hg and DPT-Cu complex, as well as DPT, depend upon pH, on the electrolyte solution, as well as on the concentration and ratio of the ligand and metal ion. The mechanisms of those electrode processes were investigated. Due to their strong adsorption, low concentration levels of DPT, through DPT-Hg complex reduction, and copper, through DPT-Cu complex reduction, about 1O-'M, can be determined, with the accumulation time of 10 minutes at 0.0 V (vs. Ag/AgCl), at pH 2.8 in 0.55 M NaCI.
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