Desenvolveu-se um procedimento para determinação de cobre, ferro, chumbo e zinco em amostras de gasolina. O procedimento foi baseado na pré-concentração dos metais empregando uma resina modificada com o ácido 3,4-dihidroxibenzóico (XAD-DHB), seguida da dessorção com solução ácida. Os analitos no eluato foram determinados por espectrometria de absorção atômica em chama multielementar seqüencial (FS-FAAS). As amostras de gasolina foram preparadas como microemulsões misturando-se 80 mL de amostra com 17 mL de propan-1-ol e 3 mL de solução tampão (pH 10). As variáveis físico-químicas que influenciam no processo de extração foram otimizadas. Os LODs obtidos foram 2,2 mg L -1 para Fe, 3,1 mg L -1 para Cu, 2,3 mg L -1 para Pb, e 2,6 mg L -1 para Zn. Os valores de RSDs das concentrações dos analitos nas amostras enriquecidas com 0,05 e 0,1 mg L -1 de cada metal variaram de 5,8 a 9,7%. As recuperações variaram de 82 a 99%. O método foi aplicado na determinação dos analitos em níveis de μg L -1 em amostras de gasolinas coletadas em postos revendedores de Salvador, BA, Brasil.A procedure was developed for determination of copper, iron, lead and zinc in gasoline. The procedure was based on the preconcentration of metals using a resin modified with 3,4-dihydroxybenzoic acid (XAD-DHB), followed by desorption with an acid eluent. The components in the eluate were then determined by fast sequence flame atomic absorption spectrometry (FS-FAAS). The gasoline samples were prepared as microemulsions by mixing 80 mL of sample with 17 mL of propan-1-ol and 3 mL of a buffer solution (pH 10). The chemical and physical variables influencing the extraction were optimized. The LODs obtained were 2.2 mg L -1Pb and 2.6 mg L -1 Zn. The RSDs ranged from 5.8 to 9.7% in samples spiked with 0.05 and 0.1 mg L -1 of each metal and recoveries varied from 82 to 99%. The procedure was suitable for determination of the analytes at mg L -1 levels in gasoline samples collected from several gas stations in Salvador, State of Bahia, Brazil.
Keywords: preconcentration, metal, gasoline, solid phase extraction, FS-FAAS
IntroductionGasoline and diesel engines emit a large amount of pollutants and are major sources of urban air pollution.
1Emissions related to automobile fuel combustion contribute significantly to atmospheric pollution, ultimately reducing air quality and negatively affecting human health. The gasoline used as fuel in automobiles may contain metalloids and metallic elements such as Pb, Cu, Zn, Ni, Fe, As, Cd, Hg, Se and Tl. These elements are derived from the raw product, but can also be introduced as additives during production or contaminants during storage. 2 The presence of such species in gasoline can cause various problems, such as air pollution, fuel degradation, precipitate Santos et al. 553 Vol. 22, No. 3, 2011 formation, and possible damage of motor parts. In addition, the presence of several metallic species in fuel reduces the efficiency of catalytic reactors in vehicle exhaust systems, thereby increasing the emission of exha...
