Transcript Dias nummer 1

CCalfa & CCbeta - Revisited
Jens Hinge Andersen
[email protected]
CCα=CB + 2.33*SB
CCα=CMRL + 1.64*SMRL
CCβ=CCα + 1.64*SS
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
Blank
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
(average measurement of blank sample)
CCalfa
is a
measurement result
A confirmed measurement
above CCalfa means that
the sample is
non-compliant
Blank
1% of measurements
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
(average measurement of ”Unknown” sample)
Blank
Unknown
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DTU Food, Technical University of Denmark
Measurement results
sometimes above CCalfa
– sometimes not –
meaning that the sample
cannot with certainty be
classified as
non-compliant
Presentation name
17/04/2008
CCbeta is that concentration
in a sample that (almost)
always will give us a
measurement above CCalfa
CCbeta
is a
concentration in the
sample
Blank
CCbeta
5% of
measurements
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DTU Food, Technical University of Denmark
(and a confirmed measurement
above CCalfa means that
the sample is non-compliant)
Presentation name
17/04/2008
CCbeta
is a
concentration in the
sample
CCalfa
is a
measurement result
CCbeta is that
concentration in a sample
that we can expect to give us
a measurement above CCalfa
i.e. the result:
Non-compliant sample
Recommendation 2002/657
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Presentation name
ISO 11843
17/04/2008
Examples:
• Substances with MRL
• Screening methods
• Testing estimates of CCalfa and
CCbeta
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
MRL
CCbeta
CCbeta is that concentration in
a sample that will give us a
measurement above CCalfa
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
Methyl
prednisolon in
porcine liver:
No MRL
Blank
CCbeta
Methyl
prednisolon in
bovine liver:
MRL=10µg/kg
MRL
10
CCbeta
DTU Food, Technical University of Denmark
Presentation name
17/04/2008
Methyl
prednisolon in
porcine liver:
No MRL
MRPL
Blank
CCbeta
Methyl
prednisolon in
bovine liver:
MRL=10µg/kg
MRL
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CCbeta
DTU Food, Technical University of Denmark
Presentation name
17/04/2008
Examples:
• Substances with MRL
• Screening methods
• Testing estimates of CCalfa and
CCbeta
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
Annex II. Determining Cut-Off Levels and CCβ in a semiquantitative screening test
in
Guidelines for the validation of screening methods for residues
of veterinary medicins (20/1/2010)
Measurements
of true concentration:
CCb
Cut-off value
Threshold: CCa
Measurements
of true concentration:
Blind sample
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
MRL
Blank
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CCbeta
DTU Food, Technical University of Denmark
Presentation name
17/04/2008
Screening
MRL
Blank
CCbeta
Confirmation
MRL
CCbeta
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
Examples:
• Substances with MRL
• Screening methods
• Testing estimates of CCalfa and
CCbeta
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
Blank
samples
should
(almost)
CCbeta
is
thatresults
concentration
in a
Analytical
above
never
give (almost)
usfullfill
a measurement
sample
that
always will
CCa should
all
above criteria
CCalfa above
give
us a measurement
identification
CCalfa
Blank
CCalfa
CCbeta
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
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
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
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
CCbetaisisbelow
belowthe
thelevel
levelofof
the illegal dye present, you will be assessed as if your result
was zero”.
FAPAS
Blank
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CCbeta
DTU Food, Technical University of Denmark
Presentation name
17/04/2008
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!).
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
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
Screening
LC‐MS/MS). In such cases CC‐beta is quoted for the 'screening
method' with MRL
a lower CC‐alpha for the 'confirmatory method'.
However
the method is never actually used as a screening method
Blank
CCbeta
(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!).
Confirmation
MRL
CCbeta
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008
CCbeta
is a
concentration in the sample
CCalfa
is a
measurement result
CCbeta is that concentration in a sample that we can expect to give us a
measurement above CCalfa i.e. the result: Non-compliant sample
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DTU Food, Technical University of Denmark
Presentation name
17/04/2008