Alloy formation by mg under-potential deposition on al from nitrate melts

Magnesium was underpotentially deposited on aluminium electrodes from magnesium nitrate-ammonium nitrate melts at temperatures ranging from 390 to 500 K. The electrochemical techniques used were linear sweep voltammetry and potential step. Electrodes were studied by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). It was found that reduction processes of nitrate, nitrite and water (when present), in the underpotential range studied, took part simultaneously with magnesium underpotential deposition. Consequently, magnesium UPD reduction and stripping voltammetry peaks were not pronounced and well defined. Nevertheless, EDS, EDX and XRD measurements showed evidence of Mg2Al3, MgAl2 and Al12Mg17 alloys formed by underpotential deposition of magnesium onto aluminium substrate

Alloy formation by underpotential deposition of Mg on Al from nitrate melts

Magnesium has been underpotentially deposited on aluminium electrodes from magnesium nitrate and magnesium nitrate-ammonium nitrate melts at temperatures ranging from 85oC to 200oC. Electrochemical techniques used were cyclic voltammetry and potential step. Deposits were studied by electron microscopy, EDS and XRD. In the magnesium UPD region on Al the processes of nitrate, nitrite and water (when present) reductions take part simultaneously with magnesium UPD. The underpotential deposition of magnesium leads to Al3Mg2, Mg2Al3 i Al12Mg17 alloys formation

Fumonisins and co-occurring mycotoxins in north Serbian corn

The presence of fumonisin has not been regulated in the legislation of the Republic of Serbia. Therefore, the data on contamination of cereals, especially corn, which is highly susceptible to contamination by this toxin, are not sufficient. This paper presents the results of testing the corn samples collected in the autumn 2009 on the territory of Bačka. Samples were analyzed for the contents of fumonisins and it was determined whether there is a correlation between the moisture content, total number and class of fungi, as well as the content of aflatoxin, ochratoxin and zearalenone. Using enzymatic immunoaffinity method it was discovered that the highest percentage of samples were contaminated with fumonisins, which was probably due to the presence of Fusarium molds as the most abundant ones. The positive samples contained fumonisin in the concentrations from 0.030 to 1.52 mg kg−1. The influence of the climate and moisture content of grain on fungal contamination and mycotoxin production was analyzed in order to investigate the predictability of the presence of mycotoxins

Original scientific paper Determination of various insecticides and pharmaceuticals using

Abstract: The applicability of differently modified glassy carbon (GC) electrodes for direct or indirect determinations of various physiologically active compounds (insecticides and pharmaceuticals) in different formulations and some real samples was investigated. Samples of selected insecticides from the group of neonicotinoids with nitroguanidine (thiamethoxam and imidacloprid), cyanoimine (acetamiprid) and nitromethilene (nitenpyram) fragments, prepared in an appropriate manner, were determined by voltammetry on bare and surface-modified GC electrodes, while in the case of pharmaceuticals such as Trodon and Akineton, the chloride anion titration was followed using bare GC and phosphorus doped (P–GC) electrodes. The P–GC was also used to monitor the chloride content in the photocatalytic degradation of the (4-chloro-2-methylphenoxy)acetic acid herbicide. It was found that apart from the nature of the electrode material, the analyte and supporting electrolyte, as well as the pretreatment of the electrode surface essentially influences the applicability of the employed sensors

Voltammetric determination of the neonicotinoid insecticide thiamethoxam using a tricresyl phosphate-based carbon paste electrode

The objective of the work was to investigate the possibility of using a tricresyl phosphate-based carbon paste electrode for the direct voltammetric determination of the neonicotinoid insecticide thiamethoxam. The analyte was determined by differential pulse voltammetry in Britton–Robinson buffer pH 7.0 in the concentration range of 3.72–41.5 µg mL-1. The reproducibility of the analytical signal at the 7.29 µg mL-1 level was characterized by a relative standard deviation of 1.3 %. The applicability of the developed method was evaluated by determining thiamethoxam in a river water sample and a commercial formulation Actara 25 WG

Voltammetric determination of imidacloprid and thiamethoxam

A simple voltammetric method using a glassy carbon working electrode was developed for the determination of two members from the neonicotinoid group of insecticides: imidacloprid and thiamethoxam. The experiments showed that the voltammetric response depends on the mode of electrode surface pretreatment and the polarization mode. The response appeared to be linear in the range from 0.028 to 0.50 mg/cm3 for both analytes. The limit of detection was 0.0077 mg/cm3 for imidacloprid and 0.0085 mg/cm3 for thiamethoxam, the limit of quantitation was 0.026 mg/cm3 and 0.028 mg/cm3, respectively. The developed method was applied for the determination of these insecticides in potato samples sprayed with Confidor 200-SL or Actara 25-WG as well as commercial formulations of imidacloprid and thiamethoxam. Arecovery trial was performed to assess the accuracy of the results, the recovery values being between 95–102 % for both of neonicotinoids

Transition metal complexes with thiosemicarbazide-based ligands. Part 47. Synthesis, physicochemical and voltammetric characterization of iron(III) complexes with pyridoxal semi-, thiosemi- and S-methylisothiosemicarbazones

The reaction of warm EtOH solutions of FeX3·nH2O (X = Cl, NO3) with tridentate ONX (X = O, S, N) pyridoxal semi-, thiosemi- and S-methylisothiosemicabazones (H2L1, H2L2, H2L3, respectively) yielded high-spin octahedral mono- and bis(ligand) complexes of the formula [Fe(H2L1-3)Cl2(H2O)]Cl, [Fe(HL1,2)2]Cl·nH2O and [Fe(H2L3)(HL3)](NO3)2·H2O. The compounds were characterized by elemental analysis, conductometric and magnetochemical measurements, IR and UV-Vis spectra. Besides, a detailed voltammetric study of the complexes was carried out in DMF solution in the presence of several supporting electrolytes, to characterize the nature of the electrode processes and solution equilibria

Transition metal complexes with thiosemicarbazide-based ligands. Part 49. New complexes of iron(III) with deprotonated tridentate Schiff base pyridoxal derivatives

Three new bis(ligand) iron(III) complexes were prepared with the deprotonated ONX ligands (X = O,S,N), pyridoxal semi-, thiosemi- and S-methylisothiosemicarbazones (H2L1, H2L2 andH2L3, respectively) of the formulas [Fe(HL1,2)L1,2]. 4H2O and [Fe(HL3)2]OAc. 2H2O. The compounds were characterized by elemental analysis, conductometric and magnetochemical measurements, as well as by IR and UV-vis spectra. Detailed voltammetric investigations were carried out in DMF solutions in the presence of several supporting electrolytes to study the nature of the electrochemical processes and solution equilibria