A total of different PCB congeners

2.4. Chiral analysis by GC–HRMS
The Enantiomeric Fractions (EFs) of CBs 95, 136 and 149 were analysed according to the method of Robson and Harrad (2004), using an Agilent 7890 gas chromatograph coupled to a Micromass AutoSpec Premier high resolution mass spectrometer (GC–HRMS) tuned to greater than 10000 mass resolution. The two most abundant VX-745 of each enantiomer were recorded in Selected Ion Recording Mode (SIR).