# Commission Regulation (EC) No 152/2009 of 27 January 2009 laying down the methods of sampling and analysis for the official control of feed (Text with EEA relevance), Division 7.1.2.2: Calibration with reference samples

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

Alternatively, a calibration curve prepared from at least four reference samples (see point 7.2.4): one matrix blank, plus three reference samples at 0,5x, 1x and 2x the maximum level or action threshold may be used, eliminating the need to correct for blank and recovery if matrix properties of the reference samples match those of the unknown samples. In this case, the test response corresponding to two-thirds of the maximum level (see point 7.3) may be calculated directly from these samples and used as cut-off value. For checking of samples exceeding the action thresholds, an appropriate percentage of these action thresholds shall suit as cut-off value.

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Source: https://www.legislation.gov.uk/eur/2009/152/annex/V/division/B/chapter/II/division/7/division/7.1/division/7.1.2/division/7.1.2.2 (the official version)
Page: https://openlegislation.uk/eu-regulation-2009-152/annex-V/division-B/chapter-II/division-7/division-7.1/division-7.1.2/division-7.1.2.2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.