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Depletion of eugenol residues from the skin-on fillet tissue of rainbow trout exposed to ¹⁴C labeled eugenol

Meinertz, J.R., T.M. Schreier, S.T. Porcher, J.R. Smerud, M.P. Gaikowski.  2014.  Depletion of eugenol residues from the skin-on fillet tissue of rainbow trout exposed to ¹⁴C labeled eugenol.  Aquaculture, v 430, p 74-78. DOI:10.1016/j.aquaculture.2014.03.050

Abstract

The U.S. is lagging in access to an approved immediate-release sedative, i.e. a compound that can be safely and effectively used to sedate fish and has no withdrawal period. AQUI-S® 20E (10% active ingredient, eugenol) is under investigation as an immediate-release sedative for freshwater finfish. Because of its investigational status, data are needed to characterize the depletion, distribution, and identity of AQUI-S® 20E residues in fillet tissue. Rainbow trout (Oncorhynchus mykiss) were exposed to uniformly ring labeled ¹⁴C-eugenol at a nominal concentration of 10 mg/L for 60 min in 18 °C water. Fish (n = 6) were sampled immediately after the exposure (0 min) then at 30, 60, 120, and 240 min. Eugenol concentrations and characterization of 14C residues in the fillet tissue were determined by high pressure liquid chromatography and flow-through liquid scintillation counting techniques. Total ¹⁴C-residue burdens in fillet tissue were determined by tissue oxidation and static liquid scintillation counting techniques.

Maximum eugenol and ¹⁴C-eugenol equivalent residue concentrations in the fillet tissue were measured immediately after the exposure (44.5 and 38.8 μg/g, respectively). Eugenol was the primary ¹⁴C-residue (> 90% of all ¹⁴C-residues) in extracts from fillet tissue taken from fish sampled immediately after the exposure (0 min) and from fish sampled at 30 and 60 min after the exposure. The depletion of ¹⁴C-eugenol residues from the fillet tissue was rapid (t_1/2 = 26.25 min) after transferring the exposed fish to fresh flowing water.

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