THESIS APPROVAL

4) Exposure Study
Trophic transfer of naphthalene from oligochaetes to fish was
assessed using static system under control condition. At the start of the experiment, a
total of 72 fish was individually measured for initial weight and then placed in its own
aquaria. Test aquaria consisted of 1,000 ml glass beakers with 800 ml of deionized
water. Either naphthalene contaminated or control worms were rinsed with deionized
water, blotted dry, and then fed to each fish during a period of 15 min. Prey items
that were not consumed were removed from each container by using a small rubber
tube. The experiment was conducted at room temperature under a daily photoperiod
of 12 h. Air bubbles were used to maintain dissolved oxygen level kept at 5.83±0.06
mg/l. The values of pH in the water were 7.19±0.05.
At each sampling time, the fingerlings were removed from the
experiment and control aquaria. General observations on fish health and condition
were noted. They were gently rinsed with deionized water prior to being samples for
naphthalene tissue residues.
5.3 Chemical Analysis
1) Extraction
Naphthalene in water was extracted by agitation using liquid-liquid
extraction (Weinstein et al., 2003). Fifty ml of water samples were transferred into a
separatory funnel and 5 ml of normal hexane was added. Samples were mechanically
shaken for a minimum of 2 min and the solvent phase was removed from the water by
drawing into volumetric flasks. An emulsion was broken up by mixing it with sodium
sulfate. The extracts were concentrated by rotary evaporator and the residues were
then dissolved in acetonitrile to a final volume of 1 ml prior to HPLC analysis.
Sediments were extracted by following the method of Bangkedphol
(2004). About 1 g wwt sediment was removed, placed on aluminum foils and allowed
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