Coupled in-tube and on-fibre solid-phase microextractions for cleanup and preconcentration of organic micropollutants from aqueous samples and analysis by gas chromatography-mass spectrometry.

Matrix interference removal is an important step when large volumes of aqueous samples are required to be processed to detect trace levels of analytes. A combination of two sample extraction methods has been used in this work with the aim of cleanup and preconcentration of analytes. For first objective, mild but preferential sorption of a range of analytes has been performed with in-tube solid-phase microextraction (SPME) using polytetrafluoroethylene (PTFE) tubing, and for the second, the eluate from in-tube SPME was subjected to on-fibre SPME using DVB/Caboxen/PDMS (30/50 microm) fibre. Knitting of PTFE tubing created secondary flow pattern that enhanced radial diffusion and retention of organic analytes. Up to 2 mgL(-1) of a broad range of substances that are not extracted by PTFE include nitrogen containing aromatic heterocyclic compounds, anilines, phenols and certain organophosphorus pesticides, thus providing a clean extract using this method of sample preparation. The proposed combination of in-tube and on-fibre SPME produced a rectilinear calibration graph over 0.03-150 microgL(-1) of a range of analytes using 60 mL of aqueous sample. The overall recovery of analytes was in the range 27-78%. The detection limits were between 6.1 and 21.8 ngL(-1). The R.S.D. was in range 5.4-8.2% and 4.2-6.5% in the analysis of respectively 2 and 20 microgL(-1) of analytes.