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ANNEX VU.K.METHODS OF ANALYSIS TO CONTROL UNDESIRABLE SUBSTANCES IN FEED

[F1B. DETERMINATION OF THE LEVELS OF DIOXINS (PCDD/PCDF) AND PCBs U.K.

CHAPTER III U.K. Sample preparation and requirements for methods of analysis used in offical control of the levels of non dioxin-like PCBs in feed

1. Field of application U.K.

The requirements set out in this Chapter shall be applied where feed is analysed for the official control of the levels of non-dioxin-like PCBs and as regards sample preparation and analytical requirements for other regulatory purposes, which includes the controls performed by the feed business operator to ensure compliance with the provisions of Regulation (EC) No 183/2005.

2. Applicable detection methods U.K.

Gas chromatography/Electron Capture Detection (GC-ECD), GC-LRMS, GC-MS/MS, GC-HRMS or equivalent methods.

3. Identification and confirmation of analytes of interest U.K.
3.1.Relative retention time in relation to internal standards or reference standards (acceptable deviation of +/– 0,25 %).U.K.
3.2.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(1).U.K.
3.3.Requirements for GC-MS techniquesU.K.

Monitoring of at least the following number of molecular ions or characteristic ions from the molecular cluster:

(a)

two specific ions for HRMS;

(b)

three specific ions for LRMS;

(c)

two specific precursor ions, each with one specific corresponding transition product ion for 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 %

3.4.Requirements for GC-ECD techniquesU.K.

Results exceeding the maximum level shall be confirmed with two GC columns with stationary phases of different polarity.

4. Demonstration of performance of method U.K.

The performance of the method shall be validated in the range of the maximum level (0,5 to 2 times the maximum level) with an acceptable coefficient of variation for repeated analysis (see requirements for intermediate precision in point (9).

5. Limit of quantification U.K.

The sum of the LOQs(2) of non-dioxin-like PCBs shall not be higher than one-third of the maximum level(3).

6. Quality control U.K.

Regular blank controls, analysis of spiked samples, quality control samples, participation in inter-laboratory studies on relevant matrices.

7. Control of recoveries U.K.
7.1.Suitable internal standards with physico-chemical properties comparable to analytes of interest shall be used.U.K.
7.2.Addition of internal standards:U.K.

Addition to products (before extraction and clean-up process).

7.3.Requirements for methods using all six isotope-labelled non-dioxin-like PCB congenersU.K.
(a)

results shall be corrected for recoveries of internal standards;

(b)

recoveries of isotope-labelled internal standards shall be between 60 and 120 %;

(c)

lower or higher recoveries for individual congeners with a contribution to the sum of non-dioxin-like PCBs below 10 % are acceptable.

7.4.Requirements for methods using not all six isotope-labelled internal standards or other internal standards:U.K.
(a)

recovery of internal standard(s) shall be controlled for every sample;

(b)

recoveries of internal standard(s) shall be between 60 and 120 %;

(c)

results shall be corrected for recoveries of internal standards.

7.5.The recoveries of unlabelled congeners shall be checked by spiked samples or quality control samples with concentrations in the range of the maximum level. Recoveries for these congeners shall be considered acceptable, if they are between 60 and 120 %.U.K.
8. Requirements for laboratories U.K.

In accordance with the provisions of [F2Regulation (EU) 2017/625], laboratories shall be accredited by a recognised body operating in accordance with ISO Guide 58 to ensure that they are applying analytical quality assurance. Laboratories shall be accredited following the EN ISO/IEC 17025 standard. In addition, the principles as described in Technical Guidelines for the estimation of measurement uncertainty and limits of quantification for PCB analysis shall be followed when applicable(4).

9. Performance characteristics: criteria for the sum of non-dioxin-like PCBs at the maximum level U.K.
a

Use of all six 13 C-labelled analogues as internal standards required.

Isotope dilution mass spectrometry a Other techniques
Trueness – 20 to + 20 % – 30 to + 30 %
Intermediate precision (RSD %) ≤ 15 % ≤ 20 %
Difference between upper and lower-bound calculation ≤ 20 % ≤ 20 %
10. Reporting of the results U.K.
10.1.The analytical results shall contain the levels of the individual non-dioxin-like PCBs and the sum of those PCB congenersreported as lower-bound, upper-bound and medium-bound in order to include a maximum of information in the reporting of the results and thereby enabling the interpretation of the results according to specific requirements.U.K.
10.2.The report shall include the method used for the extraction of PCBs.U.K.
10.3.The recoveries of the individual internal standards shall be made available in case the recoveries are outside the range referred to in point 7, in case the maximum level is exceeded and in other cases upon request.U.K.
10.4.As the expanded measurement uncertainty is to be taken into account when deciding about the compliance of a sample, that parameter shall also be made available. Thus, analytical results shall be reported as x +/– U whereby x is the analytical result and U is the expanded measurement uncertainty using a coverage factor of 2 which gives a level of confidence of approximately 95 %.U.K.
10.5.The results shall be expressed in the same units and with at least the same number of significant figures as the maximum levels laid down by [F3the CMU Regulations].]U.K.
(1)

[F1Congeners often found to co-elute are for example PCB 28/31, PCB 52/69 and PCB 138/163/164. For GC-MS also possible interferences from fragments of higher chlorinated congeners shall be considered.]

(2)

[F1The principles as described in the Guidance Document on the Estimation of LOD and LOQ for Measurements in the Field of Contaminants in Feed and Food (http://ec.europa.eu/food/safety/animal-feed_en) shall be followed when applicable.]

(3)

[F1It is highly recommendable to have a lower contribution of the reagent blank level to the level of a contaminant in a sample. It is in the responsibility of the laboratory to control the variation of blank levels, in particular, if the blank levels are subtracted.]

(4)

[F1Current requirements are based on the TEFs published in: M. Van den Berg et al, Toxicol Sci 93(2), 223–241 (2006).]