International audienceThe modified carbon paste electrode with Ru(III) complex was studied as a novel sensor for the determination of nitrite. The behavior of NO2− at the electrode surface was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). EIS provided useful information on the charge transfer resistance (R) at the electrode/solution. The EIS measurements showed that R is low at oxidation potentials, and decreases with increasing temperature. The increase of the constant phase element with temperature is due to the accumulation of nitrite on the electrode, thus, facilitating the electron transfer between electrode and NO2−. CV was used to study the effect of pH on the electro-catalytic oxidation of NO2− and to determine the limit of detection (LOD). CV measurements showed a good linear relationship between the oxidation current and the concentration of NO2− over a wide concentration range 0–1.38 × 10−2 mol L−1. Low detection limit of 1.39 × 10−6 mol L−1 toward NO2− was obtained. LOD decreased by 23.2% compared to that determined using cavity microelectrode. © 2016 Elsevier Lt

A novel bis-[1-(2-[(2-hydroxynaphthalen-1-yl) methylidene]amino}ethyl)-1-ethyl-3-phenylthiourea] Schiff base (L) and its binuclear palladium and ruthenium complexes have been prepared and characterized by ESI-MS, elemental analysis, NMR (H NMR, C NMR, COSY, NEOSY and HSQC), FT-IR, ATR, UV-Visible spectra, TGA measurements, conductivity and cyclic voltammetry. The experimental results and the molecular parameters calculated using DFT method revealed a square planar geometry around Pd and octahedral geometry around ruthenium metal. The antibacterial activity of the ligand L and its complexes was evaluated against different human bacteria. In addition, the formation constants of the synthesized Schiff base-metal complexes and the systems formed with these chelates and cholesterol were estimated using spectrophotometric technique. The detection of cholesterol using novel Pd and Ru Schiff base complexes was studied using fluorometric method, and the measurements showed that the sensitive fluorometric response towards cholesterol analysis was determined using palladium complex. The limit of detection (LOD) of cholesterol calculated using this complex (4.6 μM) is lower (better) than LOD found using ruthenium complex (19.1 μM) and different compounds previously published around linear range of 0-5 mM.

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