| dc.description.abstract | Manganese, iron, copper, zinc, cadmium and lead
concentrations were determined on a total of 218 fish
and 20 sediments using atomic absorption spectrophotometry.
Representative fish species were collected from different
localities within the Winam gulf of Lake Victoria and
Mombasa Town (Indian Ocean), viz. Latest ni1oticus,
Oreochromis niloticus, Labeo victorianus, Haplochromis
sp., Synodontis victoriae and shilbe mystus (from lake
victoria) and Caranx armatus, Va1amugil sehe1i, Pel10na
ditchela, Lethrinus miniatus, Mega1aspis cordyla,
Ab1ennes hians, sphyraena forsteri, Archamia macroptera,
Gazza minuta and Pempheris oualensis (from Mombasa).
The destruction of organic matter (fish muscle) was
achieved but the wet-oxidation method with nitric and
sulphuric acids., The method incorporates use of an
anti-foam, and sample sizes up to 109 can be processed
in an aluminium block, with improved detection limits.
Factors affecting the determinatio~n of the trace metals .... ..
have been studied and the resu lt s"are repo rt ed ; : Two
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methods fOT the analysis of the sediment samples were
compared: using nitric acid and nitric-su1phuric acids
in combination.
The analytical procedures were optimized and
verified with regard to precision and accuracy
(reproducibility) and by use of IAEA certified reference
materials viz: Lake Sediment, fish solubles, milk powder
and freeze- dried animal blood, and the results obtained
are in agreement with certified values. Quantitation
was performed by a standard addition technique. Evaluation
of the method was further done by analysis of cigarettes.
The detection limits were determined both experimentally,
as well as deduced from the results obtained for each
element, thus completing qualification of the procedure.
Mean recoveries obtained for spiked samples were:
98-108% for manganese, 97-102% for iron, 95-106% for
copper, 94-103% for zinc, 96-102% for cadmium and
92-107% for lea,p. | en |
