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CCalfa & CCbeta - Revisited

CCalfa & CCbeta - Revisited. Jens Hinge Andersen jhia@food.dtu.dk. CC α =C B + 2.33*S B CC β =CC α + 1.64*S S. CC α =C MRL + 1.64*S MRL. Blank. Blank. CCalfa is a measurement result. (average measurement of blank sample).

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CCalfa & CCbeta - Revisited

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  1. CCalfa & CCbeta - Revisited Jens Hinge Andersen jhia@food.dtu.dk CCα=CB+ 2.33*SBCCβ=CCα+ 1.64*SS CCα=CMRL+ 1.64*SMRL

  2. Blank

  3. Blank CCalfais ameasurement result (average measurement of blank sample) A confirmed measurement aboveCCalfameansthat the sample is non-compliant 1% of measurements

  4. Blank (average measurement of ”Unknown” sample) Measurement resultssometimesaboveCCalfa– sometimes not – meaningthat the sample cannot with certaintybeclassified as non-compliant Unknown

  5. Blank CCbeta is thatconcentration in a sample that (almost) alwayswill give us a measurement aboveCCalfa CCbetais aconcentration in the sample CCbeta (and a confirmed measurement aboveCCalfameansthatthe sample is non-compliant) 5% of measurements

  6. CCalfais ameasurement result CCbetais aconcentration in the sample CCbeta is thatconcentration in a sample thatwecanexpect to give usa measurement aboveCCalfa i.e. the result:Non-compliant sample Recommendation2002/657 ISO 11843

  7. Examples: • Substances with MRL • Screening methods • Testingestimates of CCalfa and CCbeta

  8. MRL CCbeta CCbeta is thatconcentration in a sample thatwill give us a measurement aboveCCalfa

  9. Methylprednisolon in porcine liver: No MRL Blank CCbeta MRL CCbeta Methylprednisolon in bovine liver: MRL=10µg/kg

  10. Methylprednisolon in porcine liver: No MRL MRPL Blank CCbeta MRL CCbeta Methylprednisolon in bovine liver: MRL=10µg/kg

  11. Examples: • Substances with MRL • Screening methods • Testing estimates of CCalfa and CCbeta

  12. Annex II. Determining Cut-Off Levels and CCβ in a semi-quantitative screening testinGuidelines for the validation of screening methods for residues of veterinary medicins (20/1/2010) Measurements of true concen-tration: CCb Cut-offvalue Measurements of true concen-tration: Blind sample Threshold: CCa

  13. MRL Blank CCbeta

  14. Screening MRL MRL Blank CCbeta CCbeta Confirmation

  15. Examples: • Substances with MRL • Screening methods • Testingestimates of CCalfa and CCbeta

  16. Blank Blank samples should (almost) never give us a measurement aboveCCalfa CCbeta is thatconcentration in a sample that (almost) alwayswill give us a measurement aboveCCalfa AnalyticalresultsaboveCCashouldfullfill all identificationcriteria CCalfa CCbeta

  17. FAPAS 2011: PT for dyes in fish: “If you analyse for an illegal dye that is in the test material, and do not identify it, and your CCalfa is below the level of the illegal dye present, you will be assessed as if your result was zero”. FAPAS Blank

  18. FAPAS 2011: PT for dyes in fish: “If you analyse for an illegal dye that is in the test material, and do not identify it, and your CCalfa is below the level of the illegal dye present, you will be assessed as if your result was zero”. FAPAS 2011: PT for dyes in fish: “If you analyse for an illegal dye that is in the test material, and do not identify it, and your CCbeta is below the level of the illegal dye present, you will be assessed as if your result was zero”. FAPAS Blank CCbeta

  19. FVO 2011: E-mail to Member States: Increasingly there is a trend that the same analytical technique is being used both for screening and confirmation (usually LC‐MS/MS). In such cases CC‐beta is quoted for the 'screening method' with a lower CC‐alpha for the 'confirmatory method'. However the method is never actually used as a screening method (e.g. for B1 testing), therefore it is incorrect to quote the higher CC‐beta as this is not actually used as a threshold over which confirmation would be carried out.(In fact the CC‐beta quoted is for the method as a confirmatory method!).

  20. FVO 2011: E-mail to Member States: Increasingly there is a trend that the same analytical technique is being used both for screening and confirmation (usually LC‐MS/MS). In such cases CC‐beta is quoted for the 'screening method' with a lower CC‐alpha for the 'confirmatory method'. However the method is never actually used as a screening method (e.g. for B1 testing), therefore it is incorrect to quote the higher CC‐beta as this is not actually used as a threshold over which confirmation would be carried out.(In fact the CC‐beta quoted is for the method as a confirmatory method!). Screening MRL MRL Blank CCbeta CCbeta Confirmation

  21. CCalfais ameasurement result CCbetais aconcentration in the sample CCbeta is thatconcentration in a sample thatwecanexpect to give us a measurement aboveCCalfa i.e. the result: Non-compliant sample

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