ANNEX VMETHODS OF ANALYSIS TO CONTROL UNDESIRABLE SUBSTANCES IN FEED
F1B. DETERMINATION OF THE LEVELS OF DIOXINS (PCDD/PCDF) AND PCBs
CHAPTER II Sample preparation and requirements for methods of analysis used in offical control of the levels of dioxins (PCDD/Fs) and dioxin-like PCBs in feed
6. SPECIFIC requirements for GC-MS methods to be complied with for screening or confirmatory purposes
6.2. Control of recoveries
6.2.5.
Control of recovery is required. 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, shall be 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 %.