Dispersive solid-phase extraction followed by liquid-liquid microextraction for extraction and preconcentration of PBDEs from sediment samples prior gas chromatography-mass spectrometry

JORGELINA C. ALTAMIRANO; FONTANA, ARIEL R.; WUILLOUD, RODOLFO G.

Kyoto, Japon

Simposio; V INTERNATIONAL SYMPOSIUM ON BROMINATED FLAME RETARDANTS; 2010

PBDEs are one of the brominated flame retardants used to protect potentially flammable materials by increasing the resistance to ignition and delaying the spread of fire (Birnbaum and Staskal, 2004, Rahman et al., 2001). PBDEs are additives of polymeric material and, thus are not chemically bound to the chemical structure. Therefore, they may leach from the surface of their product into the environment (de Wit, 2002, de Wit et al., 2006, Stapleton and Dodder, 2008). PBDEs are persistent, have low water solubility and high affinity to suspended particles, which favors their bioaccumulation in hydrophobic mediums of the biota such as sediments (de Wit, 2002). Sediment is one of the major sink to PBDEs in the aquatic environment. Since contaminants can be bioavailable in sediment to different aquatic organisms, the study of sediment is an important stage in tracing possible exposure route to aquatic biota (Yusà et al., 2006). The analysis of sediment samples for PBDEs determination requires highly efficient extraction techniques because the analytes tend to be very strongly bound to the sample matrix. Furthermore, due to the low concentration of the target analytes in sediment samples, it is necessary to count on highly efficient preconcentration techniques for their determination. In the last ten years, the development of robust analytical methodologies to quantify PBDEs in environmental matrices has reported a rapid growth. Several analytical approaches for both sample preparation and instrumental analysis have been proposed (Covaci et al., 2007, D´Silva et al., 2004). Room temperature lixiviation is an alternative for extracting PBDEs from sediment samples. It can be assisted by auxiliary energies such as ultrasonic (US) radiation in order to favor the kinetic of the mass-transfer process of the target analytes to the liquid phase. It leads to an increment in the extraction efficiency of the technique in a minimum amount of time (Luque de Castro and Priego-Capote, 2006, Luque de Castro and Priego-Capote, 2007). Thus, it turns into an ultrasound assisted leaching (USAL) technique. Due to the low concentration of PBDEs in sediment samples it is necessary to apply a preconcentration technique prior to their GC?MS/MS determination. Recently, a novel microextraction technique, dispersive liquid-liquid microextraction (DLLME), have been reported (Rezaee et al., 2006). DLLME uses an extraction solvent mixture including a high-density non-polar water immiscible solvent (extraction solvent) and a polar water miscible solvent (disperser solvent). DLLME have high preconcentration capabilities in a very short time. The main disadvantage of the DLLME is that it is not a selective extraction technique and also fails if phases do not separate even after centrifugation (in the case of heavily contaminated extracts). Thus, in order to overcome this problem it is necessary to include a clean-up stage after the analyte leaching from the sample and previous to DLLME technique. Dispersive solid-phase extraction (DSPE) was recently introduced as a rapid and simple technique for clean-up crude extracts of different matrixes (Anastassiades et al., 2003). It is based on the addition of the sorbent material into the extract to remove the matrix co-extractives, which is then separated from the extract bulk by centrifugation. The use of DSPE after USAL would increase the extraction efficiency of DLLME technique and extend its applicability to sediment samples. The purpose of the present work is to develop a new analytical methodology based on DSPE-DLLME, and demonstrate its applicability for extraction and preconcentration of PBDEs from sediment samples prior their determination by GC?MS/MS. To this aim, four of the most commonly found PBDEs in sediment samples were selected as target analytes: 2,2′,4,4′- tetrabromodiphenyl ether (BDE-47), 2,2′,4,4′,5-pentabromodiphenyl ether (BDE-99), 2,2′,4,4′,6-pentabromodiphenyl ether (BDE-100), 2,2′,4,4′,5,5′-hexabromodiphenyl ether (BDE-153). The influence of several variables on the performance of the analytical methodology were studied and optimized over the analytical response of the PBDEs. The analytical performance of DSPE-DLLME-GC?MS/MS methodology was evaluated in terms of method detection limits (MDLs), repeatability and linear working range.