Analysis of BTEX in experimental columns containing neat gasoline and gasoline-ethanol

Abstract

O principal objetivo deste trabalho foi o estudo do perfil de evaporação de BTEX (benzeno, tolueno, etilbenzeno e xilenos) em amostras de gasolina pura e mistura de gasolina-etanol. Os vapores de duas colunas lacradas contendo areia de fundo de rio e água destilada foram monitorados por 18 dias por SPME (micro extração em fase sólida). BTEX que permaneceram na fase aquosa e na areia foram extraídos por SPE (extração em fase sólida) e Soxhlet, respectivamente. A análise instrumental foi realizada por cromatografia a gás com detector por ionização de chama (GC/FID). Tolueno e etilbenzeno apresentaram as maiores volatilizações na coluna contendo a mistura gasolina-etanol. Esta distribuição pode ser devida à ocorrência de forças atrativas envolvendo moléculas de etanol e de BTEX. O benzeno foi o composto com maior retenção na fase areia da coluna contendo a mistura gasolina-etanol. The main objective of the present study was to assess the evaporation profile of BTEX (benzene, toluene, ethylbenzene and xylenes) in neat gasoline and gasoline-ethanol blend fuels. The vapors from two sealed columns containing river sand and distilled water were monitored during 18 days by SPME (solid-phase microextraction). BTEX that remained in the water and sand phases were extracted by SPE (solid-phase extraction) and Soxhlet, respectively. Instrumental analysis was performed by gas chromatography using a flame ionization detector (GC/FID). Toluene and ethylbenzene showed the highest volatilizations in the gasoline-ethanol column and the occurrence of attractive intermolecular forces among ethanol and BTEX molecules can be responsible for this distribution. Benzene showed the lowest reduction of concentration in the sand compartment in the gasoline-ethanol column.

Ultrafast gas chromatography method with direct injection for the quantitative determination of benzene, toluene, ethylbenzene, and xylenes in commercial gasoline

“…All of the performance characteristics were obtained under optimized conditions. LOD, LOQ, and linearity presented better results when compared to Filho et al .…”

“… applied 1D and comprehensive 2D GC with ionic liquid capillary columns to quantify the compounds studied in this paper. On the other hand, Filho et al applied SPME and SPE coupled to GC to seek the same objective. However, for such techniques, the samples require preprocessing and the time of BTEX compounds analysis is extremely long (around 30 min).…”

“…Among the modern methods of chemical analysis, undoubtedly chromatography has a place of prominence referring to the separation, identification, and quantification of chemical compounds, especially with organic volatile compounds. In direct analysis in gasoline fuel or other matrices (i.e., water), the time of BTEX compounds analysis is extremely long (around 30 min) when compared to ultrafast gas chromatography (UFGC)—the method applied and developed in this paper—consequently, faster analyses would provide an increase in laboratory productivity .…”