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Microcolumns containing 8-hydroxyquinoline azo-immobilized on controlled pore glass were incorporated in a field sampler for on-site collection, isolation and preconcentration of trace metal ions in waters of the Okavango Delta, Botswana. Sequestered trace metal ions were recovered by elution with 0.5ml of 1.5M nitric acid, and determined by graphite furnace atomic absorption spectrometry (GFAAS)...
The paper summarises the findings of recent studies carried out to assess the levels of pesticide residues in water, sediment, soil and some biota collected from different parts of Tanzania. Although the intention is to cover the whole country, so far the studies have focused on areas with known large-scale pesticide use (Southern Lake Victoria and its basin, TPC sugar Plantations in Kilimanjaro region,...
A sensitive flow injection chemiluminescence (FL-CL) method for the determination of cephalosporin antibiotics, was developed. The method was based on that cephalosporin antibiotics could enhance the CL reaction of glyoxal and KMnO 4 in sulfuric acid. Method development included the optimization of reagent concentrations and flow-rate. Under the optimized conditions, three cephalosporin antibiotics:...
Three enantioselective, potentiometric membrane electrodes (EPMEs) based on macrocyclic glycopeptide antibiotics-vancomycin and teicoplanin (modified or not with acetonitrile)-were proposed for the determination of l- and d-enantiomers of methotrexate (Mtx). The linear concentration ranges for the proposed enantioselective membrane electrodes were between 10 -6 and 10 -3 ...
A graphite furnace atomic absorption method of platinum and palladium determination after their separation from environmental samples has been presented. The samples were digested by aqua regia and the analyte elements were separated on the dithizone sorbent. The procedure of sorbent preparation was described and their properties were established. Two various procedures of elution by thiourea and...
The chromatographic performance of a new zirconia stationary phase (DPZ) modified with dodecylamine-N,N-dimethylenephosphonic acid (DDPA) is studied by using positional isomers as probes. The DDPA modified zirconia via one phosphonic group has a polar inner-layer and a non-polar outer-layer on its surface. The alkyl chain of outer-layer provides the hydrophobic interaction, while the polar inner-layer...
A Suntest solar simulator with arc xenon lamp was used to irradiate pure linear alkylbenzene sulfonates (LAS) standard and some commercial LAS solutions. The ozonation treatment was carried out in a pilot plant air-lift type reactor. Kinetic degradation curves were obtained showing an apparent first order reaction in both cases. Extraction and preconcentration of samples was carried out by off-line...
Processing of foods, especially dehydration is known to result in alteration of sensory and nutritional qualities. Cowpea leaves is one of the common leafy vegetables consumed in Kenya that contain high levels of pro-vitamin A compounds and has good carotene retention during processing. A tasting panel was trained using a quantitative descriptive analysis (QDA) test that was developed and used to...
A new method for the fluorometric determination of zearalenone (ZEN) based on its reaction with βNADH in the presence of the enzyme 3α-hydroxysteroid dehydrogenase (3α-HSD) is described. The procedure is based on the change in fluorescence intensity that takes place during the enzymatic reaction (excitation at 340nm and emission at 454nm). The optimum reaction conditions and the analytical characteristics...
Use of seawater electrolytically enriched with hypochlorite and the in situ generation of hypochlorite on the high seas, stand a good chance for disinfection and decrease of bio and non-biodegradable organics in effluent before discharged into estuaries and deep oceans. Enriched seawater effectively decreased the biological oxygen demand measured over 5 days (BOD) and chemical oxygen demand (COD)...
The equilibrium constants and molar absorptivities for the fast formation of a 1:3 complex between cadmium(II) (Cd(II)) and dithizonate anion, in the presence of cationic and non-ionic surfactants, allowed a simple and fast spectrophotometric determination of total cadmium. Indeed, the molar absorptivities of the Cd(II)-dithizone (Dz) complex formed in the presence of the neutral Triton X-100 and...
Immunosensors and biochemical array detection systems based on electrochemical transducers have many advantages such as low detection limit, fast response, simple design and ease of miniaturization. However, further development of such sensors will depend on the availability of suitable substrates that can be converted by a labeling enzyme to an electrochemically active product. Here, we report the...
An amperometric biosensor was prepared by in situ deposition of horseradish peroxidase (HRP) enzyme on a polyaniline (PANI)-doped platinum disk electrode. The PANI film was electrochemically deposited on the electrode at 100mVs -1 /Ag-AgCl. Cyclic voltammetric characterization of the PANI film in 1M HCl showed two distinct redox peaks, which prove that the PANI film was electroactive...
A low temperature electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) method was developed for the determination of the refractory yttrium, using 1-(2-pyridylazo)-2-naphthol (PAN) as chemical modifier. The trace yttrium was vaporized as PAN complex into plasma from a graphite furnace at a comparatively low temperature of 1200 o C. The operation...
Sorption properties of baker's yeast cells, characterised as Saccharomyces cerevisiae were evaluated for trace enrichment of metal ions: Cd 2+ , Cr 3+ , Cr 6+ , Cu 2+ , Pb 2+ and Zn 2+ from aqueous environments. Metal concentration was determined by flame atomic absorption spectrometry (FAAS). Parameters affecting metal...
Stabilisation of electrochemically deposited Prussian blue (PB) films on glassy carbon (GC) electrodes has been investigated and an enhancement in the stability of the PB films is reported if the electrodes are treated with tetrabutylammonium toluene-4-sulfonate (TTS) in the electrochemical activation step following the electrodeposition. A multi-enzyme PB based biosensor for sucrose detection was...
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