Journal of Chromatography A, 1216 (2009) 7755–7760 Contents lists available at ScienceDirect Journal of Chromatography A journal homepage: www.elsevier.com/locate/chroma Combining microwave-assisted extraction and liquid chromatography–ion-trap mass spectrometry for the analysis of hexabromocyclododecane diastereoisomers in marine sediments Hsin-Hung Wu, Hsin-Chang Chen, Wang-Hsien Ding ∗ Department of Chemistry, National Central University, Chung-Li 320, Taiwan article info Article history: Received 28 April 2009 Received in revised form 30 August 2009 Accepted 2 September 2009 Available online 8 September 2009 Keywords: Hexabromocyclododecane Microwave-assisted extraction Liquid chromatography Mass spectrometry Sediment analysis abstract An efficient microwave-assisted extraction (MAE) procedure coupled with high performance liquid chromatography–electrospray-ion-trap mass spectrometry (HPLC–ESI-ITMS) has been evaluated to determine hexabromocyclododecane diastereoisomers (-, - and -HBCD) in marine sediments. The composition of the LC mobile phase (consisting of water, methanol and acetonitrile) and the parame- ters of electrospray ionization (ESI) were evaluated to obtain chromatographic baseline separation and high sensitivity for the detection of these diastereoisomers. The effects of various operating parameters on the quantitative extraction of the HBCDs through MAE were systematically investigated. The three diastereoisomers were then quantitated by HPLC–ITMS employing ESI operated in the negative ioniza- tion mode. The HBCDs were extracted from the sediments through MAE using 40 mL of acetone/n-hexane (1/3, v/v) at 90 ◦ C for 12 min. The limits of quantitation (LOQ) ranged from 25 to 40 pg/g (dry weight) in 5 g of the sediment samples. The recoveries of the HBCDs in spiked sediment samples ranged from 68 to 91% (relative standard derivation: 2–11%). The extraction efficiency of the MAE technique was also compared with Soxhlet extraction and pressurized liquid extraction. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Hexabromocyclododecanes (HBCDs) are nonaromatic bromi- nated cyclic alkanes that are used widely as additive brominated flame retardants in buildings, in upholstery textiles and in elec- tronic devices as the thermal insulation. The commercially used HBCD comprises three diastereoisomers: -, - and -HBCD [1]. The physical and chemical properties of HBCDs are similar to those of many persistent organic pollutants: persistency, bioac- cumulation, long-range transport and toxicity (see [2] and the references cited therein). They have been detected worldwide in variety of environmental samples, including air, fresh water, sedi- ments, aquatic biota, indoor air and dust, and even in human blood and breast milk [1–7]. Their possible application as replacements for polybrominated diphenyl ethers (PBDEs) is causing increas- ing concern in terms of environmental and health issues, thereby stimulating our interest to develop a quick and reliable method to determine their occurrence and fate in various environment. Many analytical methods have been developed to determine HBCDs in aqueous and solid samples; they have been reviewed extensively by Covaci et al. (see [8] and the references cited ∗ Corresponding author. Tel.: +886 3 4227151x65905; fax: +886 3 4227664. E-mail address: wanghsiending@gmail.com (W.-H. Ding). therein). Liquid chromatography coupled to mass spectrometry (LC–MS) or tandem mass spectrometry (LC–MS–MS) with electro- spray ionization (ESI) is currently the best method for determining diastereoisomers in environmental samples [8]. These techniques have provided baseline separation and high sensitivity for the determination of HBCDs at trace levels. Although Soxhlet extrac- tion has been the primary option for the extraction of HBCDs from soil and sediment samples with mixtures of acetone and n-hexane (1/1 or 1/3, v/v) providing the best recoveries, this approach is time- and solvent-consuming. Recently, microwave-assisted extraction (MAE) has been developed successfully to extract various pes- ticides and pollutants from sediment and soil samples [9–14]. Because the microwave energy heats the sample and the solvent in a closed extraction vessels, the temperature can be increased rapidly, thereby promoting the diffusion of analytes and solvent- mediated swelling of the solid samples; as a result, MAE accelerates the rate of extraction and reduces solvent consumption. In this study, MAE coupled with HPLC–ESI-ITMS was employed to determine the three HBCD diastereoisomers in marine sediment samples. The effects of the mobile phase composition on the chro- matographic baseline separation and ESI-ITMS parameters for the best signal response were evaluated. The effects of the operating parameters of the MAE process (i.e., the composition and volume of the extractive solvent, and the extraction temperature and time) on the efficient and quantitative extraction of HBCDs were also 0021-9673/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2009.09.001