Development of Molecularly Imprinted Sol-Gel SPME Devices for the Determination of Polybrominated Diphenyl Ethers

Introduction. Polybrominated diphenyl ethers (PBDEs) are undoubtedly the most important group of organohalogenated compounds that captures the attention of environmental scientists in recent years. PBDEs are widely used flame retardant additives in polymers and textiles and are present in nearly all of our daily appliances. There are growing evidences that these brominated flame retardants are entering the global ecosystem at a significant rate (de Boer et al., 2000; Ikonomou et al., 2002; Norstrom et al., 2002; Kierkegaard et al., 2004). In order to assess their risk to the environment and public health, their levels in the various environmental compartments have to be closely monitored. This relies on the development of reliable, rapid and sensitive analytical techniques for polybrominated organic compounds. Solid-phase microextraction (SPME) is one of the advanced sampling and sample preparation techniques that are useful in the determination of trace organics in environmental samples (Polo et al., 2004; Salgado-Petinal et al. 2006). There are already numerous reports on the use of SPME for PBDE determination in water and solid samples. However, there are still problems to be solved before the technique can be applied to more demanding sample matrices, such as blood plasma. We have examined the applicability of most commercially available SPME coatings in the direct sampling of PBDEs in aqueous media and found them to show rather poor analyte affinity and repeatability, especially towards heavier PBDE congeners. There is a call for the development of new and more robust SPME coatings that possess selective affinity for PBDE congeners. In this context, we explored the feasibility of using molecularly imprinted sol-gel silica films as SPME coatings. A series of ORMOSIL films of various compositions were fabricated and examined for stability under the SPME sampling and GC desorption conditions. The sol-gel silica coating from phenyltrimethoxysilane and tetraethoxysilane (TEOS) is found to be the most suitable candidate. Molecular imprinting of BDE209, the heaviest PBDE congener, into the sol-gel SPME coating can be easily accomplished by dissolving the congener into the sol prior to gelation. The resulting sol-gel SPME coating is found to possess much higher stability and affinity towards PBDE congeners. In this work, we present the detail fabrication procedures for the molecularly imprinted SPME coating and the evaluation of its performance in the determination of BDE209 and other lighter PBDE congeners in various environmental sample matrices.