Identification of PAH conjugates in fish bile using high pressure liquid chromatography/electrospray mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) have been identified in marine sediments and water associated with many types of industrial activities and the presence of PAH metabolites in finfish bile is evidence for recent acute or chronic exposure to these contaminants. Analysis of bile for PAH metabolite conjugates, using reverse phase high pressure liquid chromatography (RP-HPLC) with fluorescence detection and quantification as benzo[a]pyrene (BaP) equivalents, revealed higher concentrations of these metabolites in English sole (pleuronectes verulus) collected from a pulp mill site (Crofton) and an aluminum smelter site (Kitimat) compared to a reference site (Bamfield). The chromatograms of bile from English sole caught at the polluted sites showed different complex mixtures of fluorescent compounds. The portion of biliary metabolite conjugates fluorescing at BaP wavelengths (380nm/430nm) that may be derived from mutagenic or carcinogenic PAHs cannot be determined quantitatively without identification of individual metabolites. Studies are being conducted to identify specific mutagenic or carcinogenic PAH precursors through their metabolite conjugates (glutathiones, glucuronides, sulfates) in bile of English sole by HPLC combined with electrospray mass spectrometry (HPLC/ES-MS). A RP-HPLC method using a Supelcosil LC-ABZ column and gradient elution has been developed that is compatible with ES ionization and still allows separation of PAH metabolitemore » conjugates. Good separation of available glucuronide, sulfate and glutathione standards has been obtained, with the ES-MS operating in the negative ion mode, method detection limits in the pM range have been established from flow injections of individual conjugate standard solutions. HPLC/ESMS measurements of metabolite conjugates in English sole bile from coastal British Columbia sites will be presented.« less