Determination of PAHs and OH-PAHs in rat brain by gas chromatography tandem (triple quadrupole) mass spectrometry

An efficient and selective method for the quantitative determination of polycyclic aromatic hydrocarbons (PAHs) and their monohydroxylated metabolites (OH-PAHs) in rat brain tissue using gas chromatography tandem (triple quadrupole) mass spectrometry (GC-MS/MS) was developed and validated. The list of molecules investigated comprised the 16 PAHs from the US-EPA list and 53 of their OH-PAHs. Brain extract was submitted to enzymatic hydrolysis, followed by liquid-liquid extraction, and then purified by solid-phase extraction. Limits of quantification ranged from 0.6 to 29 pg/mg and from 0.5 to 30 pg/mg for PAHs and OH-PAHs respectively. The analysis of rat brain samples exposed to PAH mixture (0.01-1 mg/kg, 28 days, ip) demonstrated that this method allowed the detection of 16 PAHs and 28 OH-PAHs out of the 69 analytes investigated. Mean concentrations of PAHs in animal brain samples exposed to 1 mg/kg of PAH mixture ranged from 3.0 ± 2 pg/mg for benzo[b]fluoranthene to 146 ± 29 pg/mg for phenanthrene. Concomitantly, mean concentrations of OH-PAHs ranged from 0.49 ± 0.4 to 26.5 ± 23 pg/mg for 2-OH-chrysene and 1-OH-pyrene respectively. This study proves, for the first time, the bioavailability of most of the PAHs and OH-PAHs in mammalian brain tissue and should provide an important new tool for future neurotoxicological studies.