h i g h l i g h t s " The Fast-HRGC method allows chromatograph analysis of 8 min for gasoline. " The method provides a good resolution between benzene and 1-methylcyclopentene. " The method developed allows the quantification of benzene in gasoline.
a b s t r a c tGasoline is a very complex mixture of hundreds different components and, from a toxicological point of view, benzene is the most hazardous one. Some of the methods recommended present many drawbacks, such as time-consuming. Thus, the need to develop fast methods for routine analysis of benzene is fundamental to the quality control of gasoline. Therefore, the present work compared two different capillary columns to develop a new method for routine analysis of benzene in gasoline by HRGC-FID. The quantitative analysis was carried out using external standard from 0.1%, 0.5%, 1.0%, 1.5% to 2.0% (v/v) of benzene in ethanol and in spiked gasoline. The results show that, using Fast-HRGC, it is possible to separate benzene and other 245 compounds found in gasoline in analysis time of 8 min with high accuracy.
In this study, the removal of BTEX (benzene, toluene, ethylbenzene, p-xylene and o-xylene) from aqueous solution using Moringa oleifera seed cake (MOSC) was investigated. The effect of parameters such as contact time, pH and initial BTEX concentration were studied to optimize the conditions for maximum removal. Maximum removal values of 75 +/- 1%, 85 +/- 2%, 86 +/- 2%, 88 +/- 2% and 87 +/- 1% were obtained for benzene, toluene, ethylbenzene, p-xylene and o-xylene, respectively, at pH 7.0, with a 20 min contact time for an adsorbent dose of 10 g L(-1) of 1 mg L(-1) BTEX concentration. The adsorption data fitted the Langmuir and Freundlich adsorption isotherms. The capacity of MOSC to adsorb BTEX was compared with that for a commercial activated carbon. The results from the two methods were not significantly different (judged by t-test at 95% confident interval). A low cost, easy purchase and the satisfactory experimental results indicated that MOSC is a promising natural material for the removal of BTEX from aqueous solution.
Organochlorine pesticides are persistent and bioaccumulated compounds in the environment. These substances have various impacts on human health and wildlife. Therefore they require environmental monitoring. In this work the levels of organochlorine pesticides were determined in rivers in the state of Goiás, in central Brazil. Some preserved areas of the Cerrado ecosystem and major rivers were observed. High levels of organochlorine pesticides in the water resources were found in all regions of Goiás state due to environmental degradation and intense agricultural activity.
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