Determination of volatile organic compounds (VOCs) in water and soil using solid phase microextraction

This report summarises studies of simultaneous determination of some volatile organic compounds including aromatic hydrocarbons (BTEX), light aliphatic hydrocarbons (C-5-C-8) and their halogen derivatives in water, soils and wastes by HS-SPME/GC/MS (Headspace Solid Phase Microextraction/Gas Chromatography/Mass Spectrometry). It has been proven that under the same conditions for the analysed compounds greater microextraction recovery is reached from a gaseous phase than from a liquid one. An impact of several salting out agents on the increase of concentration of the determined compounds in the headspace has been examined. It has been discovered that the most effective agent is sodium sulfate. Adsorption process from the gaseous phase to the moment of reaching equilibrium has been examined for the analysed compounds and for some SPME fibres. The adsorption time varied from several minutes in the case of low-molecular compounds such as pentane to 30 min in the case of n-butylbenzene, at the desorption time of 5 min. A temperature program for capillary column DB-624 and working parameters for the mass spectrometer have been optimised. The linear range for a selected 100 Pm PDMS fibre and the applied GC/MS technique was from 0.05 to 100 mug L-1, method detection limit varied depending on the analysed substance from 0.05 to 0.7 mug L-1 for water and from 0.003 to 0.040 mg kg(-1) for soils. Standard recovery from surface water determined with 100 mum PDMS fibre varied from 90 to 110% and from sewage or soils and wastes - from 75 do 118%. While using GC equipped with ECD detector the linear range of the method for halogen derivatives was from 0.002 to 1.000 mug L-1 and the MDL varied from 0.0035 to 0.0092 mug L-1.