Analysis of Volatile Organic Compounds in Environmental Water Samples and Soil Gas by Solid-Phase Microextraction

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Abstract
The basic principle of solid-phase microextraction (SPME) is equilibration. Therefore, all possible interferences on the extraction process should be taken into account in order to perform a reliable calibration for the quantitative analysis of environmental samples. Humic acids and suspended mineral oxides showed no effect on the SPME analysis of volatile organic compounds (VOCs), whereas salt had a positive effect on the extraction efficiency. The linearity was good in all cases, the precision of repeated analysis was around 5% average standard deviation, and detection limits were in the ng/1 range. Thus, SPME can be applied for the quantitative analysis of VOCs in various environmental water samples, such as sea water, groundwater and heterogeneous samples like river and lake water containing suspended solids. SPME was established also as an alternative to liquid-liquid extraction in the study of TiO2-catalysed photodegradation mechanisms. Finally, two new SPME sampling probes were designed and tested for rapid, on-site measurements of organic micro pollutants in groundwater and soil gas. SPME is suited ideally to provide low-cost evaluation of groundwater properties in unconventional hydrogeologic settings, such as underground excavations, and to provide preliminary data on which to base the selection of boreholes for more extensive casing installation and instrumentation.