Browsing by Author "Assefa Mulugeta"

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    Determination of common ions and heavy metals in bottled waters consumed in Ethiopia
    (Addis Ababa Universty, 2008-07) Assefa Mulugeta; Chandravanshi B.S. (Professor)
    Concentration of six trace elements, nine major ions and two physical parameters in six different brands of bottled water obtained from Ethiopia were investigated. For comparison purpose, sample of tap water from Addis Ababa was also analysed. Cd, Cu, Cr, Fe, Pb, Zn, Na, K, Mg and Ca contents of the drinking water samples were determined by FAAS. Concentrations of F-, Cl-, NO3-, SO42-and PO43- were determined by IC. The data showed the variation of the investigated parameters in water samples as follows: Fe 0.035-0.086 mg/L, Zn 0.088-0.334 mg/L, Na 2.77-48.03 mg/L, K 1.19-4.40 mg/L, Mg 1.30-3.42 mg/L, Ca 1.63- 11.59 mg/L, F- < 0.20-0.92 mg/L, Cl- 4.84-12.38 mg/L , NO3- < 0.42-8.38 mg/L, SO42- < 0.36- 10.26 mg/L pH 7.35-8.34 and EC 119.7-579.3 μS/cm. Cd, Cu, Cr, Pb and PO43- concentrations in all the drinking water samples were below the detection limit. Concentration levels of all the analysed trace metals and common ions investigated in all examined water samples were below the maximum contaminant level prescribed by WHO regulations. Some of the physical parameters, pH and electrical conductivity were determined. pH in all the samples was with in the permissible limit of WHO drinking water quality guidelines. Key Words: FAAS, IC, Bottled Water, Metal, Common Anions, Physical Parameters
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    N-Phenylcinnamohydroxamio Acid as an Analytical Rlagent for Solvent Extraction And Spectrometric Determination Of Vanadium (V)
    (Addis Ababa Universty, 1983-06) Assefa Mulugeta; Chandravanshi B.S. (PhD)
    N-phenylcinnamohydroxamic acid (PORA) has been found to form a convenient extraction system for uRnadium (V) in presence of p-chlorophenol and also in SON media. PORA reacts with vanadium (V) to give a 1:2 complex (having a broad peak around 54-0 nm with 6200 litres/mole/cm). In the presence of an adduct forming substance (p-chlorophenol) synergic extraction of the metal and marked absorbance enhancement into chloroform have been observed on the basis of formation and hyper and bathochromic shift of the hydrophobic species formed. Similar effect is seen in the mixed ligand complex system. The complexes are found to have the composition 1:2:1 or 1:2:2 (V: POUA: PhOR) depending upon the nmount of p-chlorollhenol available during the reaction; and 1:2;2 (V: PORA: bOn) mixed