Isolation and identification of fluoranthene biodegradation products

Abstract

Analytical procedures for isolating and identifying the biodegradation products of fluoranthene, a model four ring polycyclic aromatic hydrocarbon, were improved for ex-situ experiments using the pure bacterial strain Pasteurella sp. IFA. The stable degradation products were determined over a 10 day incubation period. The most efficient method for isolating the metabolites was a two step liquid–liquid extraction using ethyl acetate. Because of the polar nature of fluoranthene metabolites, separation by GC proved inefficient. Their chromatographic properties, however, were improved by derivatisation: silylation with N-methyl-N-(trimethylsilyl) trifluoroacetamide for hydroxy and carboxy groups, oxime formation with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride for carbonyl groups, or a combination of both. The metabolites were identified using gas chromatography with mass selective detection (GC-MS/SCAN, SIM). Using this method we were able to identify and quantify six stable fluoranthene metabolites (9-fluorenone-1-carboxylic acid, 9-fluorenone, 9-hydroxy-1-fluorene-carboxylic acid, 2-carboxybenzaldehyde, benzoic acid and phenylacetic acid).