Abstract
Alkyl-substituted PAHs are more abundant than their parent analogues in crude oil, and they can also be more toxic and bioaccumulate to a higher degree following oil exposure. Although PAH metabolization in organisms is considered a "detoxifying" mechanism, metabolites are occasionally found to be more toxic than the parent PAH. In the current study, we exposed zebrafish embryos to a suite of alkylated phenanthrene homologues. Alongside routine determination of PAH body burden, developmental and physiological effects after exposure, we developed a method for quantifying a wide range of alkyl-substituted PAHs found in embryos after exposure. Using characteristic molecular fragmentation patterns of known PAH metabolite standards, as well as chromatogram patterns observed in positive control bile samples from Atlantic salmon exposed to crude oil and in single alkyl-PAH exposed zebrafish, we could identify unknown alkyl-PAH metabolite clusters. Quantification was based on the response factor of known unsubstituted PAH metabolite standards using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Thereafter, we detected and quantified these alkyl-PAH metabolites in embryonic haddock exposed to crude oil. This work is part of a larger project aimed at determining the exact cardiotoxic components of crude oil.