Differential Linear Sweep Research Articles

Electrocatalytic oxidation of NO at electrode modified with Nafion–CoII–1,10-phenanthroline film and its application to NO detection

The preparation and electrochemical characterization of a platinum electrode modified with Nafion–Co(phen)2 as well as its application are described. Nafion film was employed as a carrier of Co(phen)22+ and a barrier against anionic species. The Co(phen)22+ mediator was immobilized on a Nafion film by self-assembly. The resulting Nafion–Co(phen)2 film electrode exhibited catalytic activity toward NO oxidation at a potential around 0.70 V (versus Ag/AgCl/KCl(sat)). The electrode was selective against nitrite and ascorbate. In phosphate buffer solution (pH 7.4), the NO oxidation current measured by 1.5 order differential linear sweep voltammetry and the NO concentration showed a linear relationship in the range 1.4 × 10−7–5.0 × 10−6M.

The new approaches to electrochemical investigations of blood components

The differential linear sweep voltammetry technique is used to investigate the effect of blood components (erythrocytes, leukocytes, plasma, lymphocyte fraction) on active intermediates of an oxygen reduction ( ·OH, H 2O 2). Lymphocytes are shown to be most effective in the inhibition of radical intermediates of an oxygen reduction. The distinctions in the antiradical activity are found between intact lymphocytes of healthy mice and transformed lymphocytes of ascitic tumor (lymphoblastes). These distinctions depend on cell concentrations and are clearly observed at 2×10 4 ml −1 or higher concentrations of lymphocytes in a chamber. The established peculiarities of the blood components' influence on oxygen intermediates can be used to elucidate the involvement of the blood components into antioxidative protection mechanisms.

Differential linear sweep and differential cyclic voltabsorptometry in a long-path-length spectroelectrochemical cell: Eqr, Eir and ErCi′

The theory of differential linear sweep voltabsorptometry (DLSVA) and differential cyclic voltabsorptometry (DCVA) in long-path-length spectroelectrochemistry is presented for irreversible (Eir), quasi-reversible (Eqr) and ErCi′ mechanisms under conditions of semi-infinite diffusion. It is concluded that this method may be suitable for estimating electrochemical parameters because it is more sensitive than the approach using an optically transparent electrode. All the theoretical results re experimentally verified. The standard heterogeneous rate constant k s and the transfer coefficient α of two electrochemical quasi-reversible systems (methylene blue in 1.0 M HCl and indigo carmine in 0.1 M HCl) were estimated using the simplex method and good fits between theory and experiment were obtained. A system comprising K 4Fe(CN) 6 + ascorbic acid in 0.5 M HNO 3 + 0.5 M glycine buffer was utilized to test the theory for the ErCi′ mechanism. The rate constant of the pseudo-first-order catalytic reaction was also estimated by simplex fitting. The estimated results are in agreement with experimental values.

Determination of zinc in uranium by differential linear sweep oscillographic polarography with a perchlorate-fluoride electrolyte

Determination of zinc in uranium by differential linear sweep oscillographic polarography with a perchlorate-fluoride electrolyte

Determination of aluminium in plutonium metal by differential linear sweep oscillographic polarography

A procedure has been developed for the polarographic determination of aluminium in plutonium. The plutonium is separated by anion-exchange in a nitrate medium, and the aluminium is determined in the eluate by use of Superchrome Garnet Y. The aluminium concentration range in the polarographed solutions is 0.020–0.800 μg ml . The average recovery of aluminium was 99.3 %, relative standard deviation 7.2%. Of 20 common impurities found in plutonium métal, only molybdenum and titanium cause significant interference; both can be removed by ion-exchange.

Determination of uranium in plutonium by differential linear sweep oscillographic polarography

The polarographic behavior of uranium in hydroxylamine hydrochloride was investigated by differential oscillographic polarography. A procedure is presented for the determination of uranium in plutonium for concentrations of uranium greater than 10 p.p.m. Analyses of solutions containing 22 common impurities found in plutonium metal revealed that antimony, copper, and titanium cause significant interference. A reversible peak corresponding to a one-electron reduction was obtained with a peak potential of -0.167 V vs. Hg pool electrode. The diffusion coefficient is 0.51·10 -5 cm 2/sec and the diffusion current constant is 1.59 with an average relative standard deviation of 2.28%. The peak current of uranium can be affected by hydrochloric, nitric, perchloric, and sulfuric acids, depending on the acid concentration.