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

Abstract

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.

Metabolite identification by mass spectrometry: forty years of evolution

“…However, thermal degradation during DLI was observed. For example, molecular ions for the sulphate and glucuronide of benzo(a) pyrene were not observed by DLI (Bieri and Greaves 1987). In the same study, it was shown that DLI could be more sensitive than the moving belt for some compounds; it exhibited 20-fold greater sensitivity for ranitidine.…”

Applications of mass spectrometry in drug metabolism: 50 years of progress

“…Direct liquid introduction (DLI) represented a significant improvement with less thermal decomposition and higher sensitivity compared with the ''moving belt'' interface (Henion et al, 1983). However, phase II metabolites such as glucuronide and sulfate conjugates were unstable under DLI conditions (Bieri & Greaves, 1987). Continuous-flow (CF) FAB/MS/MS was used for the analysis of drugs such as penicillin G, phentolamine, cocaine, and warfarin, and good sensitivity and reproducibility were achieved by this technique (Caprioli, 1990).…”

Determination of benzo[a]pyrene sulfate conjugates from benzo[a]pyrene-treated cells by continuous-flow fast atom bombardment mass spectrometry

“…To increase the specificity with which BP-S04 can be detected and quantified, several mass spectrometric methods have been investigated. For example, it has been demonstrated that field desorption (19) and direct liquid injection HPLC (20) mass spectrometry give useful mass spectra of BP-S04. However, there are no reports of investigations in which these methods were used to identify or quantify BP-S04 produced by metabolism of BP in cells.…”