Inter-laboratory studies for the validation of solid-phase microextraction for the quantitative analysis of volatile organic compounds in aqueous samples

Inter-laboratory studies were organised with the participation of twenty laboratories for the purpose of validation of a new standard method using solid-phase microextraction (SPME) for the quantitative analysis of volatile organic compounds (VOCs) in aqueous samples. The statistical evaluation of the accuracy and precision of SPME was performed in accordance with the ISO standard concerning inter-laboratory studies on the basis of reference material and by comparison with the usual purge-and-trap and static headspace techniques. Comparable repeatability, reproducibility and accuracy were found with the SPME standard and the reference methods. Better precision of SPME was obtained by extraction from a small headspace over the aqueous phase than with the fibre immersed in water. The linearity was good in all cases and detection limits were in the low ng/l range. Thus, it is concluded that SPME is a valid alternative technique for the analysis of VOCs at trace level in various aqueous samples.