The porous spinel oxide nanoparticles, MnCo2O4, were synthesized by citrate gel combustion technique. Morphology, crystallinity and Co/Mn content of modified electrode was characterized and determined by Fourier transform infra-red spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction pattern analysis (XRD), simultaneous thermogravimetry and differential thermal analysis (TG/DTA). Nanoparticles were used for modification of glassy carbon electrode (GCE) and new sensor was applied for simultaneous determination of Pb(II) and Cd(II) ions in water samples with the linear sweep anodic stripping voltammetry (LSASV).The factors such as pH, deposition potential and deposition time are optimized. Under optimal conditions the wide linear concentration range from 0.05 to 40 μmol/dm3was obtained for Pb(II), with limit of detection (LOD) of 8.06 nmol/dm3 and two linear concentration ranges were obtained for Cd(II), from 0.05 to 1.6 μmol/dm3 and from 1.6 to 40 μmol/dm3, with calculated LOD of 7.02 nmol/dm3. The selectivity of the new sensor was investigated in the presence of interfering ions. The sensor is stable and it gave reproducible results. The new sensor was succesfully applied on determination of heavy metals in natural waters.

The determination of Pb and Cu with a Nafion-modified glassy carbon electrode and MnCo 2 O 4 nanoparticles as working electrode for anodic stripping voltammetry was described. Pb and Cu were accumulated in HCl/KCl (0.1 mol/dm 3 ) at a potential of -1.4 V (vs. Ag/AgCl electrode) for 480 s followed by a linear sweep anodic stripping voltammetry (ASV) scan from -1.0 to +0.5 V.Under optimum conditions the calibration curves were linear in the range of 0.01 -8 mg/dm 3 and 0.01 -5 mg/dm 3 for Pb and Cu, respectively. Effect of sample dilution, accumulation time and potential were optimised. A study of interfering substances was performed. A significant increase in current was obtained at modified electrode in comparison with bare glassy carbon electrode. The modified electrode was successfully applied for determination of Pb and Cu in wine samples after simple preparation procedure. Pb and Cu content in wine was used for estimation of the target hazard quotient (THQ) values for minimal and maximal levels of the metals.

This work presents the development of a flow injection system for differential pulse amperometry (DPA) for diazepam determination in the presence of oxygen. The thin flow cell consisted of the bare glassy carbon electrode, reference silver/silver chloride, and stainless steel as the auxiliary electrode. Electrochemical reduction of diazepam (DZP) was characterised by cyclic voltammetry. Azomethine reduction peak was used for DZP quantification. The detector response was linear in the range 20–250 µmol/dm3 of diazepam, with a calculated detection limit of 3.83 µg/cm3. Intraday and interday precision were 1.53 and 10.8%, respectively. The method was applied on three beverage samples, energetic drink, and two different beer samples, and obtained recoveries were from 93.65 up to 104.96%. The throughoutput of the method was up to 90 analyses per hour.

Background: Diazepam belongs to the group of 1,4-benzodiapines. It is used for the treatment of anxiety, convulsions and as a muscle relaxant. The presence of 4,5-azomethine group enables its electrochemical detection Introduction: A screen-printed electrode modified with antimony film was used for the determination of diazepam in pharmaceutical preparations Methods: Electrode modification was done by ex-situ deposition of antimony on commercially available screen-printed electrode. Parameters affecting the electroanalytical response of the sensor, such as deposition potential, deposition time, and antimony concentration, were examined and optimized. The modified electrode showed enhanced electroactivity for diazepam reduction compared to unmodified electrode. Under optimal conditions, linear sweep voltammetry was used for the determination of analyte Results: The sensor showed linear dependence in the range from 0.5 to 10 μmol/L, the correlation coefficient was 0.9992. The limit of detection was 0.33 μmol/L, corresponding limit of quantification was 1.08 μmol/L. Modification enabled determination of diazepam in the presence of oxygen. Conclusion: The modified electrode was used for the determination of diazepam in tablets. Results confirmed the applicability of the electrochemical sensor

Abstract:Toxic elements are present everywhere in nature and even in raw materials and pigments used in the manufacture of cosmetics. Human bodies daily exposed to toxic elements that can be found in trace amounts in cosmetic products. These elements such as arsenic and mercury can cause local skin damage or possible, their absorption through the skin or swallowed. In this paper we determined the content of arsenic and mercury in ten lipstick samples and eight nail polishes samples by atomic absorption spectroscopy (AAS). Acid digestion with 0,1 M HCl or HNO 3 -HCl was performed. A very low concentration of Hg and As have been found in all samples in both extracts (ranged, 0.0001-0.0004 μg/g and 0.02 -0.04 μg/g respectively).