Division 6.2.1 F1

Addition of ¹³ C-labelled 2,3,7,8-chlorine-substituted internal PCDD/F standards and of ¹³ C-labelled internal dioxin-like PCB standards shall be carried out at the very beginning of the analytical method e.g. prior to extraction in order to validate the analytical procedure. At least one congener for each of the tetra- to octa-chlorinated homologous groups for PCDD/Fs and at least one congener for each of the homologous groups for dioxin-like PCBs shall be added (alternatively, at least one congener for each mass spectrometric selected ion recording function used for monitoring PCDD/Fs and dioxin-like PCBs). In the case of confirmatory methods, all 17 ¹³ C-labelled 2,3,7,8-substituted internal PCDD/F standards and all 12 ¹³ C-labelled internal dioxin-like PCB standards shall be used.