Benzene, toluene, ethylbenzene and xylenes (BTEX) are environmental pollutants, that are part of the group of pollutants called volatile organic compounds (VOC). They are found in petroleum oil and are used in industry as solvents and as a precursors for synthesis of various organic compounds and materials. BTEX compounds are toxic for humans, while benzene is also cancerogenic and teratogenic. Because the smallest fraction of BTEX compounds in environment are found in water and adsorbed to soil, they need to be preconcentrated before the analysis, for which we use extraction methods, such as solid phase microextraction (SPME). In this study we developed a method for quantification of BTEX compounds in soil, for which we used SPME as an extraction method and gas chromatography coupled with mass spectrometry for analysis.
In the general part extraction and chromatography methods, with the emphasis on gas chromatography and SPME are described. Furthermore results of the method optimisation are presented. Optimal conditions for separation of BTEX compounds with gas chromatography and optimal conditions for SPME are also described. The effect of type of fiber, temperature, duration of sample agitation and duration of extraction on SPME are graphically presented for each of the BTEX compounds, alongside with calibration curves.
Developed method has linear concentration range from 0.5 μg/g to 5.0 μg/g. Limit of detection, which we determined experimentally, was for BTEX compounds from 12.5 ng/g to 50.0 ng/g. CAR/PDMS 75 μm fiber has proven to be the most suitable fiber for extraction of BTEX compounds using SPME. The developed method has proven to be suitable for the determination of BTEX compounds in soil and was tested on the real samples of soil, that was contaminated with diesel fuel. Besides toluene, which was present in one sample in the concentration of 0.043 μg/g, the concentrations of other BTEX compounds were below the limit of detection.
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