Fibre selection based on an overall analytical feature comparison for the solid-phase microextraction of trihalomethanes from drinking water

Abstract

This paper describes the optimization of solid-phase microextraction (SPME) conditions for three different fibres (Carboxen-polydimethylsiloxane (CAR-PDMS), divinylbenzene-Carboxen-polydimethylsiloxane (DVB-CAR-PDMS) and polydimethylsiloxane-divinylbenzene (PDMS-DVB)) used to determine trihalomethanes (THMs) in water by headspace solid-phase microextraction and gas chromatography (HS-SPME-GC). The influence of temperature and salting-out effect was examined using a central composite design for each fibre. Extraction time was studied separately at the optimum values found for temperature and sodium chloride concentration (40 °C and 0.36 g mL −1). The HS-SPME-GC-MS method for each fibre was characterised in terms of linearity, detection (LOD) and quantification (LOQ) limits and repeatability. The fibre PDMS-DVB was selected as it provided a broader linear range, better repeatability and lower detection and quantification limits than the others, particularly CAR-PDMS fibre. The accuracy of the proposed method using the PDMS-DVB fibre was checked by a recovery study in both ultrapure and tap water. A blank analysis study showed the absence of memory effects for this fibre. The reproducibility (expressed as a percentage of relative standard deviation) was 6–11% and the detection limits were between 0.078 and 0.52 μg L −1 for bromoform and chloroform, respectively. Finally, the method was applied to determine THM concentration in two drinking water samples.