{
  "url": "https://openlegislation.uk/eu-decision-2002-657/annex/chapter-2.3/division-2.3.2.2",
  "json_url": "https://openlegislation.uk/eu-decision-2002-657/annex/chapter-2.3/division-2.3.2.2.json",
  "legislation": "eudn/2002/657",
  "legislation_title": "Commission Decision of 12 August 2002 implementing Council Directive 96/23/EC concerning the performance of analytical methods and the interpretation of results (notified under document number C(2002) 3044) (Text with EEA relevance) (2002/657/EC)",
  "legislation_url": "https://openlegislation.uk/eu-decision-2002-657",
  "path": "annex/chapter/2.3/division/2.3.2.2",
  "kind": "division",
  "number": "2.3.2.2",
  "heading": "Precision of quantitative methods",
  "text": "The inter-laboratory coefficient of variation (CV) for the repeated analysis of a reference or fortified material, under reproducibility conditions, shall not exceed the level calculated by the Horwitz Equation. The equation is:\nCV = 2 ( 1 – 0 , 5 l o g C ) where C is the mass fraction expressed as a power (exponent) of 10 (e.g. 1 mg/g = 10-3). Examples are shown in the table 3.\nTable 3\nExamples for reproducibility CVs for quantitative methods at a range of analyte mass fractions\nMass fraction\nReproducibility CV(%)\n(*) For mass fractions lower than 100 μg/kg the application of the Horwitz Equation gives unacceptable high values. Therefore, the CVs for concentrations lower than 100 μg/kg shall be as low as possible.\n1 μg/kg\n10 μg/kg\n100 μg/kg\n23\n1 000 μg/kg (1 mg/kg)\n16\nFor analyses carried out under repeatability conditions, the intra-laboratory CV would typically be between one half and two thirds of the above values. For analyses carried out under within-laboratory reproducibility conditions, the within-laboratory CV shall not be greater than the reproducibility CV.\nIn the case of substances with an established permitted limit, the method shall achieve within-laboratory reproducibility not greater than the corresponding reproducibility CV at a concentration of 0,5 × the permitted limit.",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "footnote",
      "label": "f1",
      "text": "(*) For mass fractions lower than 100 μg/kg the application of the Horwitz Equation gives unacceptable high values. Therefore, the CVs for concentrations lower than 100 μg/kg shall be as low as possible."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eudn/2002/657/annex/chapter/2.3/division/2.3.2.2",
    "retrieved_at": "2026-11-01T15:18:31.211349+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}