Negussie Retta

Assessment of organochlorine pesticide pollution in Upper Awash Ethiopian state farm soils using selective pressurised liquid extraction

Upper Awash Agro Industry Enterprises (UAAIE) is one of the major state farms in Ethiopia with known large-scale pesticide use. Although organochlorine pesticides (OCPs) have been applied for about three decades, no studies have been carried out on levels of residue in the region. In this work a fast selective pressurised liquid extraction (SPLE) methodology has successfully been applied for screening of 13 OCPs in 12 soil samples from different fields in UAAIE, which further strengthen this methodology. Quantitative and qualitative analyses were done using a dual column gas chromatography-electron capture detection system (GC-ECD) and a GC equipped with a mass spectrometer (MS), respectively. The main contaminants identified comprised of previously used persistent organic pollutants (POPs) and currently used insecticides. Low concentrations or non-detectable levels of certain OCPs (aldrin, dieldrin, endrin, and heptachlor) indicate a positive phasing out of these persistent organic pollutants (POPs). Similarly HCHs were found in few soils and at low concentrations. Endosulfans and DDTs were detected in substantial amounts in the soils with Sigmaendosulfans up to 56000 and SigmaDDTs up to 230 ng g(-1) dry weight, which is a threat to the surrounding and downstream ecosystems, especially considering that the investigated OCPs constituted 29000 l of the 63000 l of pesticide applied annually on the fields. Additional concerns must be raised concerning synergistic effects of all pesticides added.

Kinetics and mechanism for reduction of halo- and haloam(m)ine platinum(IV) complexes by l-ascorbate

Reduction of the model platinum(IV) complexes cis-[PtCl4(NH3)(2)] (1), trans-[PtCl4(NH3)(2)] (2). trans-[PtCl2(en)(2)](2+) (3), trans-[PtBr2(NH3)(4)](2+) (4), [PtCl6](2-) (5), and [PtBr6](2-) (6) with L-ascorbic acid (H(2)Asc) in 1.0 M aqueous medium at 25 degreesC in the region 1.75 less than or equal to pH less than or equal to 7.20 has been investigated using stopped-flow spectrophotometry. The redox reactions follow the rate law: -d[Pt(IV]/dt = k[H(2)Asc](tot)[Pt(IV)] where k is a pH-dependent second-order rate constant and [H(2)Asc](tot), the total concentration of ascorbic acid. The pH-dependence of k is attributed to parallel reduction of Pt(IV) by the protolytic species HAsc(-) and Asc(2-). Analysis of the kinetics data reveals that the ascorbate anion Asc(2-) is up to seven orders of magnitude more reactive than HAsc(-) while H(2)Asc is unreactive. Electron transfer from HAsc(-)/Asc(2-) to the Pt(IV)) compounds is suggested to take place by a mechanism involving a reductive attack on any one of the mutually trans-halide ligands by Asc(2-) and/or HAsc(-) forming a halide-bridged activated complex, The rapid reduction of these complexes supports the assumption that ascorbate Asc(2-) might be an important reductant at physiological conditions for anticancer active Pt(IV) pro-drugs capable of undergoing reductive trans elimination. The parameters DeltaH(not equal) and DeltaS(not equal) for reduction of Pt(IV) with Asc(2) hake been determined from the study of the temperature dependence of k

Ion-pair assisted liquid–liquid extraction for selective separation and analysis of multiclass pesticide residues in environmental waters

A new ion-pair assisted liquid–liquid extraction (IPA-LLE) method in combination with high performance liquid chromatography-diode array detection (HPLC-DAD) has been proposed for the determination of ten multiclass (six sulfonylurea and four organophosphorus ) pesticides in environmental waters. In the IPA-LLE procedure, the ion-pairing reagent tetrabutylammonium hydrogen sulfate and the organic solvent, acetonitrile, were used for extraction of the target analytes. Various parameters influencing the extraction efficiency such as the type, composition and volume of the ion-pair, volume of acetonitrile, sample pH, type and composition of the salt and effect of sonication time were studied and optimal conditions were established. Under the optimum conditions, the limits of detection and quantification of the proposed method were in the ranges of 0.5–3.0 μg L−1 and 1.8–10.0 μg L−1, respectively, and calibration curves were linear within the range of 1.8–450 μg L−1, with coefficients of determination of 0.993 or better. Intra- and inter-day precision studies, expressed as relative standard deviations, at three concentration levels, were in the range of 0.4–9.4%. The relative recoveries of the spiked environmental water samples were in the range of 73–105%, except for nicosulfuron in lake water. The results of the study revealed that the developed method involves efficient sample preparation allowing the preconcentration of analytes, followed by the use of HPLC-DAD for quantitative analysis.

Cleaner industrial production practice in Ethiopia: problems and prospects

Abstract In this article, cleaner industrial production (CIP) from the Ethiopian perception, the conditions for implementation, the barriers encountered during implementation and the strategies used are discussed. In addition, the outcome of the project is highlighted. The barriers related to the implementation of Industrial CIP in Ethiopia are mainly due to: • the lack of awareness on the part of the industrial sector; • the lack of commitments from the high level management; • the nature of the existing factories. Cleaner production as a concept is not yet fully understood in Ethiopia and for this a vigorous awareness campaign has to continuously be conducted through all possible media. So far, awareness seminars, workshops and demonstration projects have been held and proved to be effective in facilitating the implementation of National Cleaner Industrial Production Project of Ethiopia (NACIPPE 1 and 2). It was, however, sad to note that at the time of the campaign, government promulgated a decree to the effect that state-owned factories were going to be privatized any time, which, to a considerable extent lowered the managements commitment towards the CIP projects. The first and second phases of NACIPPE 1 and 2 were implemented in 1997 and 1998 respectively. Forty industries from public and private sectors participated in the training and waste audit exercises and a total of 61 audit experts and 156 audit assistants were trained. The package was divided into three technical training components and three waste audit practices. The technical support was extended by hiring a private enterprise, Chem. Tech. Center Sh. Co.

Studies on portland pozzolana cements containing Endod, a soap berry plant

Abstract Water extract from Endod retards both the initial and final setting times of Portland pozzolana cement paste. For a given water cement ratio (0.66) the slump of the concrete mix containing 0.00, 0.02, 0.05, and 0.08% of Endod increases from 2 to 9 mm and 3 to 11% sand and cement mixture was retrieved from the mould of concrete cubes. The average unit weight of the concrete cubes prepared with 0.00, 0.02, 0.05, 0.08% of Endod were 2.13, 2.04, 1.92, and 1.78 (for 28 days old) kg/L respectively.

Extract from Endod (phytolacea dodecandra), a soap berry plant, in the making of concrete

Abstract Water extract from Endod berries could be used to modify the properties of concrete or mortar in such a way as to make it more suitable in its workability and make the concrete or mortar light weight. For a given water/cement ratio (0.45) the slump of the concrete mix containing 0.02, 0.05 and 0.08% Endod increases from 3 to 8 cm and 10–25% sand and cement mixture was retrieved from the mould of a mortar cube. The volume of the mix batch increased by about 1 10 – 1 4 of its original volume. The average unit weight of the mortar and concrete cubes prepared with 0.00, 0.02, 0.05 and 0.08% of Endod were 2.12, 1.90, 1.69 and 1.66 kg/1 and 2.37, 2.25, 2.1 and 2.07 kg/1 respectively. The water extract of Endod berries, reduced the compressive strength of the mortar and concrete cubes and the flexural stress of the beams. Endod considerably retarded both initial and final setting times of the paste of cement.

Organic amines reduce trans-dichlorotetrakis(pyridine)cobalt(III) chloride to cobalt(II)

SummaryThe reaction of dichlorotetrakis(pyridine)cobalt(III) chloride. [CoCl2(Py)4]Cl, with alkyl- or arylamines in EtOH or i-PrOH yielded [CoCl2(Py)2] in all cases. This reduction of CoIII to CoII takes place only in the presence of the amines. [CoCl2(Py)2] in EtOH is oxidized by Cl2 gas and in the presence of pyridine gives [CoCl2(Py)4] +, while in pyridine alone [CoCl2(Py)4] is formed.