Feasibility of two multidimensional techniques, heart-cut MDGC and GCxGC, for the separation of PCBs and PBDEs

The feasibility of heart-cut MDGC-ECD and GCxGC-muECD for the separation of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) has been evaluated. Among the different column combinations tested, the best results were obtained when using either a DB-5 type or an HT-8 column as the first dimension combined with a mid-polar stationary phase (50% phenyl) as the second dimension. The co-elutions between the target PCBs and PBDEs in the first dimension were satisfactorily resolved once transferred to the second column. Repeatability and intermediate precision were satisfactory in both systems, considering retention times in both dimensions. Nevertheless, peak area/volume precision was better for heart-cut MDGC since software for the data analysis in the case of GCxGC was still under development. The need for multiple injections of the same extract on the heart-cut MDGC system was the main drawback since the analysis time it increased. GCxGC becomes then a valuable alternative able to achieve the same performance in one injection. However, the GCxGC data analysis is still very time-consuming and needs further development. The applicability of both separation techniques was shown using a human breast milk sample with low concentrations of PCBs (0.2-227 pg/g fresh weight) and PBDEs (1.2-41 pg/g fresh weight).