Application of 4-(2-pyridylazo)resorcinol for flotation-spectrophotometric determination of iron

Optimum conditions for flotation-spectrophotometric determination of iron with 4-(2-pyridylazo)resorcinol (PAR) based on a 1:2 FeII-PAR complex were found to be as follows: flotation solvent (chloroform), shaking time (2 min), pH (4.5±0.5), concentration of PAR (2.0×10–4 mol L–1), reducing agent (hydroxylamine hydrochloride), solvent for the floated compound (dimethylsulphoxide, DMSO), wavelength for spectrophotometric measurements (718 nm), and volumes of the organic solvents (5 mL of chloroform and 3 mL of DMSO). Calibration graphs were compared for different volumes of the aqueous phase – 10 mL and 40 mL; the corresponding linear ranges were 0.30–1.3 mg mL–1 and 0.25–1.0 mg mL–1. The iron content was successfully determined in soil samples, reference standard materials (PS-1, COOMET No. 0001-1999 BG, SОD No. 310а-98; PS-2, COOMET No. 0002-1999 BG, SOD No. 311а-98; and PS-3, COOMET No. 0003-1999 BG, SOD No. 312а-98) and zinc sulfide concentrates. KEY WORDS: Iron(II), Fe-PAR complex, Flotation, Spectrophotometry, Soils, Zinc sulfide concentrates Bull. Chem. Soc. Ethiop. 2016, 30(3), 325-332.DOI: http://dx.doi.org/10.4314/bcse.v30i3.

Floristic diversity of 'Chinarite' protected area – Rodopi municipality, Bulgaria

Abstract. Study on the species composition of vascular plants in 'Chinarite' protected area in Belashtitsa village, Rodopi Municipality, Bulgaria was conducted using the floristic analysis method. A total of 147 species of vascular plants were identified, belonging to 124 genera and 51 families. The families Poaceae, Asteraceae, Lamiaceae, Brassicaceae, Apiaceae, Rosaceae and Fabaceae are the most highly represented. The comparative analysis shows that the angiosperm taxa are dominating in the studied area. Dicotyledonous plants are prevailing among them, while monocotyledonous are significantly less in number. Molinia caerulea species, identified in the present study, has not been reported to have been found so far in the Thracian lowland floristic region

Matrix representations of the coordinates of the atoms of the molecules of H2O and NH3 in operations of symmetry

The molecule is a spatial arrangement of atoms that make it up. This arrangement defines its geometric structure. Knowing the geometry and ways to describe to great advantage in studying the electronic structure of molecules as between geometric and electronic structure there is a close connection

Influence of the direction of crossing on heterosis and transgression events in relation to the length of the vegetative period of Burley tobaccos variety group

Investigated are manifestations of real and hypothetical heterosis in terms of the length of vegetative period in ten hybrid combinations involving indigenous and introduced varieties of Burley tobacco. Each of them is represented by forward and reverse cross. The results show that more than half of the Burley tobacco hybrid combinations observed significant negative heterosis. Heterozis effect is influenced positively by distance of parents used for hybridization, and the participation of a variety Burley 1344, regardless of whether maternal or paternal component. The direction of crossing influences manifestations of heterosis effect in terms of length of the vegetative period at cross examined Burley tobacco. Heterosis effect is more pronounced when a local variety or line is used as a mother component and an imported variety is used as a father component. Transgressive manifestations in the studied hybrids in the second generation in terms of length of the vegetative period presented by degree and frequency are relatively low presented and do not have great importance for the selection practice. The direction of crossing influences the degree and to a lesser extent the frequency of transgressive events. Strong relationship between manifestations of heterosis and transgression has not been observed

CORRELATION BETWEEN SOIL CHARACTERISTICS AND IRON CONTENT IN ABOVEGROUND BIOMASS OF VIRGINIA TOBACCO

Abstract DOSPATLIEV, L., P. ZAPRJANOVA, K. IVANOV and V. ANGELOVA, 2014. Correlation between soil characteristics and iron content in aboveground biomass of Virginia tobacco. Bulg. J. Agric. Sci., 20: 1380-1385 The study was conducted on alluvial-meadow, maroon-forest soils and vertisols with Virginia tobacco. The total content of iron was measured through decomposition by HF, HClO and HNO acids. A solution of 0.005 M diethylentriaminepentaacetic acid + 0.1 M triethanolamine, pH 7.3 was used for extraction of the elements' mobile forms from soils. The plant sample preparation was made by means of dry ashing and dissolution in 3 M HCl. A Varian Spectra AA 220 Atomic Absorption Spectrophotometer was used for Fe content determination in soil and plant samples. Certified reference materials (three types of soils and tobacco leaves) were also analyzed for accurate determination of Fe concentrations. A correlation and regression analysis was conducted between pH, humus content, total and mobile iron forms in the soil, and the concentration of these elements in aboveground biomass of Virginia tobacco. It was estimated that there were statistically significant relationships between soil pH and iron concentration in Virginia tobacco plant organs. The correlation -regression analysis results showed that there were no statistically significant relationships between humus and iron concentration in aboveground tobacco biomass of Virginia tobacco. Also, the results of the correlation -regression analysis showed that there were no statistically significant relationships between the total element content in soils and iron content in aboveground tobacco biomass of Virginia type. Regression relationships were established between movable iron in the soil and element content in leaves from the lower, middle and upper harvesting zones