Formation and identification of azaarene transformation products from aquatic invertebrate and algal metabolism

The metabolism of two azaarenes, viz. acridine and phenanthridine, by aquatic organisms was studied in short-term and chronic laboratory tests. The identity of metabolites observed in the test waters was investigated with different analytical methods, including HPLC, GC and hyphenated LC- or GC-MS. The Zebra mussel (Dreissena polymorpha), one green alga species (Selenastrum capricornutum) and periphyton or bacteria transformed acridine into 9[10H]-acridinone. Phenanthridine was transformed into 5[6H]-phenanthridinone by midge (Chironomus riparius) larvae. The findings indicate that closely related isomers may undergo species-specific biotransformation. It was concluded that keto-metabolites are major products in the aquatic fate of benzoquinolines, which may be overlooked in the risk assessment of parent compounds. This study illustrates the typical problems with, as well as the potency of, chromatographic methods in the elucidation of metabolic routes of organic contaminants. (C) 1999 Elsevier Science B.V. All rights reserved.