Desorption of BTEX from activated charcoal using accelerated solvent extraction: evaluation of occupational exposures |
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Authors: | A Campos-Candel M Llobat-Estellés A R Mauri-Aucejo |
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Institution: | (1) Department of Analytical Chemistry, Faculty of Chemistry, Universitat de València, Dr. Moliner 50, 46100 Burjassot, València, Spain |
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Abstract: | A procedure for the determination of benzene, toluene, ethylbenzene and o-xylene, m-xylene and p-xylene (BTEX) in occupational environments is proposed. These compounds are extracted from activated charcoal using accelerated
solvent extraction. Operational parameters are optimized and quantitative recovery is obtained using acetonitrile as the extraction
solvent and 1-mL extraction cells, a preheat time of 2 min, a temperature of 160 °C, a pressure of 1,500 psi, a static period
of 5 min, a flush volume of 110%, two cycles and a purge time of 90 s. Determination of BTEX compounds is carried out by gas
chromatography using a flame ionization detector. The recoveries, obtained for a confidence level of 95%, are 91 ± 4, 100 ± 3,
104 ± 2, 93 ± 4, 99 ± 2 and 99 ± 2% for benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene, respectively. The detection limits are 0.5 μg for benzene, 0.7 μg for toluene and 1.0 μg for the other compounds.
The proposed procedure has been applied to real samples collected in several workplaces, like a microbiology laboratory, an
analytical chemistry laboratory, a printer’s, a car repair shop and a petrol station. From the results obtained, it can be
concluded that the occupational exposures determined are always acceptable because they are lower than the tenth part of the
recommended exposure limits (VLA-ED and VLA-EC). |
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Keywords: | BTEX Workplace Accelerated solvent extraction |
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