Preliminary study of some plasticizers compounds in sewage before and after the treatment in a sewage treatment plant Oliveira M. 1 , Dallago R.M. 2 , Dellanora R. 3 , and Nascimento I.F. 4* 1 Chemical Engineering Department, Universidade de Caxias do Sul, RS-Brazil 2 Chemistry Department, URI – campus de Erechim, RS-Brazil 3 Technological Center, URI – campus de Erechim, RS-Brazil 4 Physics and Chemistry Department – Universidade de Caxias do Sul, Avenida Francisco Getúlio Vargas, 1130, CEP 95070-560, Caxias do Sul, RS-Brazil e-mail: inascimf@ucs.br In this work it was described the extraction and analysis of plasticizers compounds, namely: dioctylphthalate (DOP) and diisobutylphthakate (DBP) in samples of liquid residues of the sewage treatment plant of the Caxias do Sul university (ETE-UCS). The samples were extracted by pH reduction, precipitation and filtration of the organic content and solvent extraction. The organic extracts were analyzed by gas chromatography with flame ionization detection (GC-FID). The target compounds were identified in the samples by comparison with the retention times of standard compounds. The analysis of the chromatographic peaks areas of the target compounds, at the entrance and launch points of the ETE-UCS shows that the percent removal grade were of 99.37 for DOP and 33.68 for DBP. These results suggest that for a satisfactory reduction of the DBP levels, other treatment methods have to be employed. Keywords: Plasticizers, liquid residues, GC-FID, DOP, DBP. 1. Introduction Plasticizers are organic esters added to polymers to facilitate processing and to increase flexibility and toughness of the final product by internal modification of the polymer molecule. Some of these plasticizers are generally high-boiling esters of dicarboxylic acids called phthalates which dominate the production and consumption of plasticizers. Dioctyl phthalate (DOP) in many instances is the sole general-purpose plasticizer produced. A chronic bioassay, completed in 1980 by the US National Toxicology Program, which was performed at extremely high doses of DOP, labeled it as a possible carcinogen. The Toy Manufacturers Association entered into a voluntary agreement with the Consumer Products Safety Commission to limit the amount of DOP in children’s pacifiers and teething rings (articles specifically intended to be mouthed) to no more than 3% of the total weight of the article. As phthalate esters (PE) are used specially in the soft polyvinyl chloride production (Bauer and Herrmann, 1997), they are widely spread in all environments, by your employment in packages, clothes, films, paints, adhesives, cosmetics, ink printers and many