Fontes, formação, reatividade e determinação de quinonas na atmosfera

Quinones are a group of semi-volatile organic substances, ubiquitous in nature, belonging to the class of oxygenated polycyclic aromatic hydrocarbons (Oxygenated PAH). These compounds are formed in biogenic processes, through the oxidative metabolism of endogenous compounds, such as catecholamines, estrogen hormones and xenobiotics, as well as directly emitted to the atmosphere, through the incomplete combustion of organic matter, especially the fossil fuels. Additionally, the quinones are formed in the atmosphere by photooxidation of Polycyclic Aromatic Hydrocarbons (PAH). Their reduction products (semiquinones and hydroquinones) are of toxicological interest, due to their ability in generate reactive oxygen species, which may cause damage to membranes, proteins and DNA and, among others damages, may lead to carcinogenesis and induce apoptosis. The most frequently used analytical methods for quantification of quinones in the atmosphere, either in its original form or as derivatized compounds, are high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) and gas chromatography coupled to mass spectrometry (GC-MS). This review aims to highlight the chemical properties of 1,2-naphthoquinone, 1,4-naphthoquinone, 1,4-benzoquinone, 9,10-phenanthraquinone and 9,10-anthraquinone, the more volatile, reactive and abundant quinones in the atmosphere, as well as the methods usually employed for their determination.