Commission Regulation (EU) No 589/2014 (repealed)Show full title

6.2. Control of recoveries

• Addition of ¹³C-labelled 2,3,7,8-chlorine substituted internal PCDD/F standards and of ¹³C-labelled internal dioxin-like PCB standards must 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 must 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 case of confirmatory methods, all 17 ¹³C-labelled 2,3,7,8-substituted internal PCDD/F standards and all 12 ¹³C-labelled internal dioxin-like PCB standards shall be used.

• Relative response factors shall also be determined for those congeners for which no ¹³C-labelled analogue is added by using appropriate calibration solutions.

• For foodstuffs of plant origin and foodstuffs of animal origin containing less than 10 % fat, the addition of the internal standards is mandatory prior to extraction. For foodstuffs of animal origin containing more than 10 % fat, the internal standards may be added either before or after fat extraction. An appropriate validation of the extraction efficiency shall be carried out, depending on the stage at which internal standards are introduced and on whether results are reported on product or fat basis.

• Prior to GC-MS analysis, 1 or 2 recovery (surrogate) standard(s) must be added.

• Control of recovery is necessary. For confirmatory methods, the recoveries of the individual internal standards shall be in the range of 60 to 120 %. Lower or higher recoveries for individual congeners, in particular for some hepta- and octa- chlorinated dibenzo-p-dioxins and dibenzofurans, are acceptable on the condition that their contribution to the TEQ value does not exceed 10 % of the total TEQ value (based on sum of PCDD/F and dioxin-like PCBs). For GC-MS screening methods, the recoveries shall be in the range of 30 to 140 %.