| Polybrominated diphenyl ethers (PBDEs) have been widely used as brominated flame retardant that is a complex mixture of hundreds of congeners. Because of its persistence, bioaccumulation, and inherent toxicity, PBDEs is now regarded as an organic chlorinated pollutant of worldwide concern, and is included persistent organic pollutants in the Stockholm Convention. The analysis of PBDEs is very difficult because of its complexity. PBDEs chromatograms acquired by using one-dimensional gas chromatography (1D-GC) show that this technique cannot be used to separate all of the PBDE congeners. In this work, a new method, the comprehensive two-dimensional gas chromatography coupled with micro-electron capture detector for the analysis of PBDE congeners, was established. Comprehensive studies were carried out on the analytical method of PBDEs in environmental matrix. This method was succesfully applied to analyze PBDEs in environmental samples. The major contents and results are as follows:It is a challenge to extract target analytes that are present at very low concentrations and separate them from complex matrices. The sample preparation (i.e. extraction and clean-up) techniques were evaluated and optimized. Soxhlet extraction (SE) and accelerated solvent extraction(ASE) were applied on sediment samples in order to evaluate their extraction efficiency. For PBDEs, the ASE extraction generally yielded higher results compared with the SE extraction, with the normalized recovery ranges of 91%-102%. For another hand, using multi-acid silica gel column and activation silica gel column is the prefered purified method, and the results indicated that reproducibility of the method were blow 20%.A new method was developed for the analysis of analytes mixtures using a comprehensive two-dimensional gas chromatography coupled with micro electron-capture detector (GCxGC-μECD). Columns with different polarity and selectivity, including DB-XLB and DB-5MS, were used as first dimension and combined with columns of increasing polarity in the second dimension, i.e. BPX-50 and BPX-70. And GC×GC-μECD parameters including temperature programs, carrier gas flow rate and modulation period etc. were also optimized. PBDE congeners were well separated with the optimized methods.We further developed and validated a sensitive and quantitative method for determining PBDE congeners in using a comprehensive two-dimensional gas chromato-graphy coupled with micro electron-capture detector (GC×GC-pECD). The sample extraction and purification treatments and the GC×GC-μECD parameters were optimized. The matrix-matched external standard calibration curves were used for quantitative analysis. Linear range of this method were 10-1500μg/L and limit of detection were 0.1-0.8μg/L of the different PBDEs. The repeatability and reproducibility at a concentration of lOμg/L evaluated as the RSDs calculated, was less than 20%(n=7). Subsequently the samples were determined by GC×GC-μECD, respectively, and the calibration curves had good linear correlations between 10 and 1500μg/L (r2>0.99). This analytical method meets the requirements for trace analysis of PBDE congeners. Comprehensive two-dimensional GC gave substantial improvements over one-dimensional GC in the PBDEs analysis. We analyzed sediment samples containing trace quantities of PBDEs to demonstrate that the developed method could be used to analyze PBDEs in environmental samples. Two methods were used to determine and compare the concentrations of PBDEs in sediment, HRGC-HRMS and GCxGC-μECD, the analysis results of GC×GC-μECD were in agreetment with those of HRGC-HRMS, it suggest that this method descired in this paper were suitable for analysis of PBDEs in environmental samples. |
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