Characterization of benzo(a)pyrene metabolites by high performance liquid chromatography-mass spectrometry with a direct liquid introduction interface and using negative chemical ionization.

Polynuclear aromatic hydrocarbons are ubiquitous pollutants that may become highly carcinogenic during their metabolism by organisms. Benzo(a)pyrene is an example of such a compound. Benzo(a)pyrene metabolite standards, which are labile, polar compounds, have been used to evaluate high performance liquid chromatography-mass spectrometry as an analytical technique for polynuclear aromatic hydrocarbon metabolites. The chromatography used microbore (1 mm i.d.) C18 columns with acetonitrile/water as the elution solvent which became the reagent/moderator gas. A direct liquid introduction interface was used and characteristic spectra were obtained in the negative chemical ionization mode. Molecular or pseudomolecular ions were obtained for five phenols (m/z 268 and m/z 267) and three trans-dihydrodiols (m/z 286, m/z 285, m/z 284). Useful spectra were also obtained for a tetrahydrotriol, four tetrahydrotetrols and three conjugated metabolites. Fragmentation usually involved loss of water and anions at m/z 284 and m/z 268 were common to most of the spectra. Variations in the source/desolvation chamber temperature between 175 degrees C and 275 degrees C caused significant alterations in the relative abundance of molecular and fragment ions. Dissociative electron capture was the dominant ionization process.