No abstract

Efforts to reduce air pollution in developing countries may require increased use of biomass fuels. Even biomass fuels are a sustainable alternative to fossil fuels there is limited quantitative information concerning heavy metal content in their ashes. Therefore, this study focuses on the determination of the heavy metal concentrations in wood pellet ash obtained from the combustion of 10 pellet brans from Bosnia and Herzegovina and Italy, the effects of adding the ashes to soils, and the assessment of health risk assessment. Ash content was determined by gravimetric method. The amount and composition of ash remaining after combustion of wood pellets varies considerably according to the type of biomass and wood from which the pellet is made. Samples were prepared by wet digestion using HNO3, and heavy metals are determined by atomic absorption spectroscopy-flame and graphite furnace. The results showed that the lowest concentration in ashes was obtained for Co 0.01 mg kg−1 and the highest for Fe 571.63 mg kg−1. The Hazard Index (HI), calculated for non-cancerous substances for children was 2.23E−01, and the total Risk index was 4.54E−05. As for adults, HI was 1.51E−02, while the Risk index value was 3.21E−06. Human health risk calculated through HI and Risk index for children and adults associated with analyzed pellets is not of significant concern. The calculated enrichment factor and metal pollution index for wood pellet ashes indicate the risk of soil contamination with heavy metals. From this point of view, analyzed samples of ashes could be a serious contaminant of soil, so further monitoring is required.

A new low potential electrochemical sensor for determination of L-cysteine based on carbon electrodes modified with Ru(III) Schiff base complex, multi-walled carbon nanotubes and Nafion is presented. Cyclic voltammetry, differential pulse voltammetry and flow injection analysis were employed. Measurements were carried out using Britton-Robinson buffer (pH 5.50). The results showed that addition of multi-walled carbon nanotubes to Ru(III) complex modified glassy carbon and screen printed carbon electrodes gives increased current signals at the potential where oxidation of L-cysteine occurs. Flow injection amperometric measurements were performed at the operating potential +0.15 V vs. Ag/AgCl (3 M KCl) electrode and showed fast electric current response for L-cysteine oxidation, demonstrating good reproducibility and stability. The sensor has a detection limit of 0.11 mg L -1 and a dynamic range of 50-500 mg L -1 . The repeatability was calculated as 2.8 %. New sensor was used for the determination of L-cysteine in pharmaceutical products.Keywords: L-Cysteine, Ru(III) Schiff base complex, multi-wall carbon nanotubes, modified glassy carbon and screen printed carbon electrodes, voltammetric and amperometric determination FULL TEXT

Three Schiff bases were synthesized by reaction of different benzaldehydes with amino acids. The characterization of these compounds was performed using IR spectroscopy, molecular calculations, thin-layer chromatography, determining the melting point and other physical characteristics. IR spectra for imino groups (C=N), which are characteristic of Schiff bases, show stretching frequency from 1629 to 1654 cm -1 . The obtained spectral results were confirmed by molecular calculations using the density functional theory (DFT) and were performed before experimental work. The DFT global chemical reactivity descriptors were calculated and used to predict their relative stability and reactivity of synthesized compounds. The antimicrobial assay of all compounds were screened for Grampositive bacteria species:

The content of macro- and microelements in dry samples of mushrooms of the species Macrolepiota procera, Boletus edulis and Cantharellus cibarius, collected at different areas in Bosnia and Herzegovina, was determined using the ICP-OES method (inductively coupled plasma optical emission spectrometry). Of the macroelements, K is the most represented, followed by S, P, Mg, and the least represented Ca and Na. Zn is the most represented of the essential microelements, followed by Fe, Se, Cu, Mn and Co. Al is the most abundant of the other trace elements followed by Ni and Cr. Of the toxic metals, the most represented is Cd, followed by Pb and As. There are differences in the concentration of micro- and macroelements in the mushrooms analysed, depending on the area from which they were collected because natural geology and geochemistry influence the content of macro- and microelements in wild edible mushrooms. The results show that the analysed mushrooms can be considered a good source of essential elements. The study also assessed potential health risks of heavy metals and the target hazard quotient (THQ) for As, Cd, Pb, Cu, Zn, Ni and Cr in the analysed mushrooms was lower than the safe level. The carcinogenic risk index revealed that Cd and Ni are the most prevalent pollutants in the mushrooms studied.