44ª Reunião Anual Virtual da SBQ

Petroleum is a complex mixture of several organic compounds, mainly hydrocarbons. In this group, toxicity is generally related to monoaromatic substances (BTEX-Benzene, Toluene, Ethylbenzene, and Xylenes) and polycyclic aromatic hydrocarbons (HPA). BTEX are more volatile and have more excellent solubility in water than soil; they are prejudicial to health, with benzene being the most dangerous, listed as a carcinogen by the International Agency for Research on Cancer (IARC). BTEX is dangerous even to people who work in spilled crude oil clean-up operations and may develop alterations in the hematological profile and liver function. Petroleum accident has been considered a concern for the environment. Between the years 2010 to 2019, there was an average of 1.8 oil spills per year in the world, above 700 tons each. In Brazil, in 2019, there was an oil spill of unknown origin that left oil slicks along the entire northeastern and states of Rio de Janeiro and Espírito Santo coast. This accident was considered the largest in terms of coastline, in which 11 states and 130 municipalities were affected. The effects of contamination caused by oil spills in the aquatic environment are linked to its physicochemical characteristics and toxicity. Given this theme, this work aims to determine an easy, fast and safe methodology to determine BTEX in water and marine sediments in a laboratory with few resources, without an automatic headspace analysis system with an injection to the chromatograph. The method for determining BTEX was performed and validated after primary study variables. The bath temperature for volatilization, mixer of the sample, matrix effect, and an internal standard were studied to obtain this analysis's best performed and variation coefficient. Vials containing the analytical standards of BTEX and internal standard of propylbenzene, prepared in synthetic seawater, having half of its total volume (40 mL) with the solution, were placed in a water bath at 60ºC, for 22 min, and vortexed for 10 seconds in the end; then an aliquot of the gas phase was removed with a gastight micro syringe of 500 µL and injected into a gas chromatograph with a flame ionization detector (Shimadzu model 2010 Plus). The temperature and time were enough to transfer the compounds into the gas phase without leaving too high the water concentration in the gas phase, damaging the chromatography column. The vortex was used to increase the efficiency of gaseous phase interaction, but without causing imbalance, as it could affect the repeatability. This work also observed that artificial seawater to perform the analytical curve eliminates matrix effect problems since the salting-out effect is significant in analyzing the transfer of nonpolar compounds from a polar matrix. With the validated methodologies, a field collection will be carried out on beaches of the State of Rio de Janeiro and Espírito Santo to assess their bathing abilities and a study of the origin of the contaminants found.