# Commission Regulation (EU) 2017/644 of 5 April 2017 laying down methods of sampling and analysis for the control of levels of dioxins, dioxin-like PCBs and non-dioxin-like PCBs in certain foodstuffs and repealing Regulation (EU) No 589/2014 (Text with EEA relevance), Division 2: Identification and confirmation of analytes of interest:

Extent: E+W+S+N.I.

Relative retention time in relation to internal standards or reference standards (acceptable deviation of +/– 0,25 %).
Gas chromatographic separation of the non-dioxin-like PCBs (from interfering substances, especially co-eluting PCBs, in particular if levels of samples are in the range of legal limits and non-compliance is to be confirmed).
For GC-MS techniques:
Monitoring of at least the following number of molecular ions or characteristic ions from the molecular cluster:
two specific ions for HRMS,
three specific ions for LRMS,
two specific precursor ions, each with one specific corresponding transition product ion for MS-MS.
Maximum permitted tolerances for abundance ratios for selected mass fragments:
Relative deviation of abundance ratio of selected mass fragments from theoretical abundance or calibration standard for target ion (most abundant ion monitored) and qualifier ion(s): ± 15 %.
For GC-ECD:
Confirmation of results exceeding the maximum level with two GC columns with stationary phases of different polarity.

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Source: https://www.legislation.gov.uk/eur/2017/644/annex/IV/division/2 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-644/annex-IV/division-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.