RESIDUES OF [C-14] MALACHITE GREEN IN EGGS AND FRY OF RAINBOW-TROUT, ONCORHYNCHUS-MYKISS (WALBAUM), AFTER TREATMENT OF EGGS

Rainbow trout, Oncorhynchus mykiss (Walbaum), eggs were exposed to [me thano-C-14] malachite green chloride on day 0 and on every third day t hereafter through day 24, with a final treatment administered to fry o n day 31. Eggs or fry were sampled before each treatment, and at selec ted times from day 31 to day 59. Malachite green equivalence in eggs a nd fry was determined by sample oxidation and liquid scintillation cou nting. Total malachite green residues increased throughout the exposur e period to 0.271 +/- 0.042 mu g g(-1) ((x) over bar +/- SD) on day 31 . Residues declined to 0.055 +/- 0.011 mu g g(-1) on day 59. The depur ation phase declined monoexponentially with a half-life of 13.3 days f or the absolute amount (mu g sample(-1)) and a half-life of 9.7 days f or the concentration of malachite green residues (mu g g(-1)). Growth dilution accounted for the 25% increase in the elimination (9.7 days) of malachite green residues. Extracts from treated eggs and fry were a nalysed by reversed-phase liquid chromatography. Three peaks were reso lved in treated eggs: chromatic malachite green, leuco malachite green and an unknown polar metabolite. Only two peaks were resolved in the fry: leuco malachite green and the unknown polar metabolite. The most prominent residue in all samples was leuco malachite green.