Determination of polybrominated diphenyl ethers and metabolites by single-drop microextraction and GC–MS/MS

Abstract

A simple, fast and virtually solvent-free method for the simultaneous determination of 13 polybrominated diphenyl ethers (PBDEs) congers and their metabolites in aqueous samples was developed using single-drop microextraction (SDME) coupled with gas chromatography-tandem mass spectrometry (GC–MS/MS). Optimization over GC–MS/MS parameters of both electron ionization (EI) and negative chemical ionization (NCI) sources were studied and compared with a result that EI is more sensitive and selective, especially for lower brominated congeners. Optimization of SDME was subsequently conducted. Under optimum conditions (1 μL drop of chlorobenzene in 2 mL sample solution, pH 5.0, 30 min extraction time, stirring rate of 400 rpm), the assay linearity of target PBDEs was confirmed over 2–3 orders of magnitudes, with a coefficient of determination (r2) ranged from 0.9929 to 0.9998. The limit of detection (LODs) and limit of quantification (LOQs) for lower brominated congeners were found to be better than 6 ng·L−1 and 20 ng·L−1, respectively. Real sample analysis with an isotopic internal standard was carried out. The recoveries, relative standard deviation (RSD) and enrichment factors obtained ranged from 73.4 to 128.0%, 7.52 to 25.0% and 8 to 60, respectively, indicating the developed method is suitable for the determination of PBDE congers in aqueous samples.