Muscles, liver and gills were taken out; composite samples of 2e5 g were used for subsequent analysis.
The samples were digested with ultra pure nitric acid (and
perchloric acid for gills 4:1) at 100 C until the solution become
clear. The solution was made up to known volume with
deionized distilled water and analyzed for Cu, Zn, Pb, Cd, Fe
and Mn using the Atomic Absorption Spectrophotometer (AAS
model GPC A932 ver. 1.1). The obtained results were expressed
as mg/g wet weight.