Suitability of polypropylene microporous membranes for liquid- and solid-phase extraction of halogenated anisoles from water samples

The applicability of disposable polypropylene microporous membranes (MMs) for the concentration of five halogenated anisoles in water samples was investigated. Two microextraction approaches, named MM solid-phase extraction (MMSPE) and liquid-liquid extraction (MMLLE), are proposed. They are based on adsorption of target species onto the surface of the dry membrane and absorption into a few microlitres of solvent embedded in the pores of the membrane, respectively. The effect of several factors, such as sampling mode, type of acceptor solvent, ionic strength of the sample, stirring, sampling time, etc., on the performance of both approaches was thoroughly assessed. After extraction, analytes were recovered from the sorbent using just 0.25 mL of n-hexane and determined by gas chromatography with micro-electroncapture detection (GC-micro-ECD). Under optimised conditions, similar precisions (RSDs from 7% to 14%, under reproducibility conditions) and limits of quantification (values between 0.3 and 15 ng L-1), as well as remarkable linear responses were attained for both techniques; however, MMSPE, operating in the headspace sampling mode (HS), showed faster kinetics for all species, was less affected by the type of matrix and the set-up of the extraction step was simpler, since immobilisation of the extraction solvent in the membrane was not necessary. Obtained results demonstrated, for the first time, the suitability of polypropylene MMs as adsorbents of lipophilic compounds. (c) 2008 Elsevier B.V. All rights reserved.