Residues of [14C]-malachite green in eggs and fry of rainbow trout, <em>Oncorhynchus mykiss</em> (Walbaum), after treatment of eggs.

Rainbow trout, Oncorhynchus mykiss (Walbaum), eggs were exposed to [methano-¹⁴C] malachite green chloride on day 0 and on every third day thereafter through day 24, with a final treatment administered to fry on day 31. Eggs or fry were sampled before each treatment, and at selected times from day 31 to day 59. Malachite green equivalence in eggs and fry was determined by sample oxidation and liquid scintillation counting. Total malachite green residues increased throughout the exposure period to 0.271 ± 0.042 µg g-^-1 (&xmacr; ± SD) on day 31. Residues declined to 0.055 ± 0.011 µg g^-1 on day 59. The depuration phase declined monoexponentially with a half-life of 13.3 days for the absolute amount (µg sample^-1) and a half-life of 9.7 days for the concentration of malachite green residues (µg 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 analysed by reversed-phase liquid chromatography. Three peaks were resolved 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. [ABSTRACT FROM AUTHOR]