Lead is known to be toxic, especially in its organic forms (organolead, OL). In the environment tetraalkyllead species are rapidly degraded by sunlight and atmospheric constituents like ozone or hydroxyl radicals. Such breakdown yields the soluble forms such as trialkyllead and dialkyllead and finally ionic lead species. The liquid membrane extraction probe (LMP) device has been developed and used as an extraction and preconcentration tool for the speciation analysis of organolead compounds by GC/MS. It allows analysis of OL species at low concentrations in complicated matrices of environmental samples. The effect of pH, stirring rate, and time that influence the extraction efficiency of OL extraction by the LMP method were optimized. The transformation of tetramethyllead in aqueous media at different concentrations of major ions K(+), Na(+), Ca(2+), Mg(2+), Cl(-), SO(4)(2-) and the application of LMP to environmental samples are presented. It was found that degradation of tetramethyllead takes between 24 and 37 days. The detection limit (LOD) of the method for all organolead species investigated is around 4.7 microg/L, with a limit of quantitation of 15 microg/L.
An analytical method for simultaneous in situ ethylation, of organolead, organotin and organomercury compounds in aqueous samples was developed using a new derivatisation agent, bromomagnesium tetraethylborate (BrMgEt(4)B). The determination of lead, tin and mercury compounds was done by species-specific isotope dilution, derivatisation and GC-inductively coupled plasma MS (GC-ICP-MS) or by GC-MS. The recovery and accuracy of the derivatisation were evaluated. The effect of pH and the relative quantity of derivatisation agent were studied.
Lipid classes and fatty acid composition of three commercially important freshwater fish species Oreochromis mossambicus (Mozambique tilapia), Clarias gariepinus (African catfish) and Cyprinus carpio (carp) obtained from an aquaculture, different river systems and fish markets from different provinces in South Africa were investigated. Fatty acids were extracted from the fish fillets through the Folch extraction method (using chloroform: methanol at the ratio of 2:1). Generally, tilapia fish species was found to be the richest in fatty acid composition. In all fish species analysed, palmitic acid (16:0) was found to be the most abundant fatty acid ranging from 18.24 to 21.84%. Appreciable quantities of essential polyunsaturated fatty acid such as docosahexaenoic (DHA) (22:6 n-3, 3.92 to 6.16%), eicosapentaenoic acid (EPA) (20:5 n-3, 1.91 to 2.92%) and arachidonic acid (20:4 n-6, 7.19 to 8.50%) were also found. Observations show that fish species obtained from Gauteng Province are richer in fatty acids compared to those in Limpopo Province. The study points out that all fish species investigated contain appreciable levels of Omega-3 (n-3) polyunsaturated fatty acids (PUFA) and are therefore suitable for an unsaturated low-fat diet. This is important especially for poor communities who cannot afford to get a balanced diet, rich in some essential fatty acids.Therefore, it is important to determine the nutritional value of local fish, since it significantly contribute to a healthy diet in rural communities.
The purpose of this study was to assess the impacts of Nyanza Municipal Solid Waste (MSW) dumping site on groundwater. As many groundwater resources are contaminated by dumping sites that are poorly managed, the equally poorly managed Nyanza MSW dumping site in Kigali could have impact on people depending on groundwater for their daily activities. Leachate samples were taken at the edge of the waste bulk and groundwater samples were collected from the wells located in the vicinity of the dumping site. Sampling was done in dry and wet season using PE bottles. Heavy metals analysis was done using flame atomic absorption method.
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