Determination of selective quinones and quinoid radicals in airborne particulate matter and vehicular exhaust particles (vol 3, pg 118, 2006)

In recent years, there has been an increasing interest in the study of the health effects of respirable particulate matter ( PM) because of its deposition in the human lungs and adverse health effects. Analysis of PM content focused on substances of toxicological importance, such as polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, aliphatic hydrocarbons, alkyl-substituted benzenes and naphthalenes, transition metals and various quinones. Recent studies shifted their attention to quinones and their toxicological role in PM. Quinones can be transformed into their semiquinones, which undergo redox cycling and reduce oxygen to produce reactive oxygen species (ROS) in biological systems, resulting in the induction of oxidative stress, especially oxidative damage to cellular components and DNA. In the present study, the presence of five quinones, 1,2-benzenediol ( catechol) and 1,4-benzenediol ( hydroquinone) in various PM samples was identified and measured quantitatively by high performance liquid chromatography. Mean concentrations of individual target quinones ranged from 15 140 ng mg(-1) in diesel and gasoline exhaust particles to 1.5-60 ng mg(-1) (or 150-1100 pg m(-3)) in airborne PM ( total suspended particulates, PM aerodynamic diameter 10 mu m, PM aerodynamic diameter 2.1 mu m) samples. Precision (repeatability and reproducibility) varied from 5 to 15%. Also, examples of electron paramagnetic resonance spectra for the single broad unstructured signal are presented, corresponding to the persistent stable semiquinone radicals of solid samples of PM, and the formation of quinoid radicals in aqueous extracts of PM samples in air-saturated carbonate-buffered solution, pH 9.5-10