Pilot PT Program for Alternative Matrices: Cocaine and Its Metabolites

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Pilot PT Program for Alternative Matrices
Cocaine and Its Metabolites

• John M. Mitchell, Ph.D.
• DTAB Meeting
• September 4, 2002
• Note See DTAB meeting transcript for verbal
  comments

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Evaluation of Analytical Values Reported for
Cocaine and its Metabolites

• Confirmatory testing
• Urine,
• GC/MS
• quantitations are in ng/mL (ppb)
• Hair,
• mostly GC/MS (2 by MS/MS)
• quantitations are in pg/mg (ppb)
• for Oral Fluid
• mostly GC/MS (1 by MS/MS)
• quantitations are in ng/mL (ppb)

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Relative Sensitivity of Assays at Cutoffs for
Benzoylecgonine
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• Variance
• Industry agreed-upon cutoffs
• Means of values reported by the participating
  laboratories
• Calculated for samples with three or more values
• Annotated above each histogram bar
• Percent coefficient of variation
• Mathematical indicator of the variation

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• Performance around cutoffs
• Graphs of reported values from each lab versus
  the mean value
• Containing 20 and 50 quantitation ranges
• Relative position of cutoff
• Distribution below the cutoff

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Source of Analytical Values

• 2 Urine Maintenance PT Cycles for all labs
  currently certified in the NLCP
• 4 Hair Pilot PT Cycles
• The 6 labs that completed all 4 cycles
• 3 Oral Fluids Pilot PT Cycles
• The 9 labs that completed all 3 cycles

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Analysis of Cocaine Analytes in UrineRecommended
Cutoffs

• Initial Test
• Benzoylecgonine 150 ng/mL
• Confirmatory Test
• Benzoylecgonine 100 ng/mL

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Analysis of Cocaine Analytes in Urine

• NLCP Maintenance PT Program
• Occasions 61-62
• 56 Laboratories
• All laboratories- GC/MS
• Samples-
• Benzoylecgonine only

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Analysis of Cocaine Analytes in Hair Recommended
Cutoffs

• Initial Test
• Cocaine 500 pg/mg
• Confirmatory Test
• Cocaine 500 pg/mg and
• at least 10 times benzoylecgonine concentration
  or
• Cocaethylene ?50 pg/mg or
• Norcocaine ?50 pg/mg

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Analysis of Cocaine Analytes in Hair

• NLCP Pilot PT Program Cycles 1,2,3,4
• 6 laboratories- 5 MS 1 MS/MS
• 6 laboratories - cocaine and benzoylecgonine
• 5 laboratories - cocaethylene
• Samples- (norcocaine not included)
• Cocaine benzoylecgonine Cycles 1,2,3,4
• Cocaine, benzoylecgonine, cocaethylene Cycles
  1,2,3

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Analysis of Cocaine Analytes in OralFluids
Recommended Cutoffs

• Initial Test
• Cocaine Metabolites 20 ng/mL
• Confirmatory Test
• Cocaine 8 ng/mL
• Benzoylecgonine 8 ng/mL

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Analysis of Cocaine Analytes in Oral Fluids

• NLCP Pilot PT Program Cycles 1,2,3
• 9 laboratories- 7 MS 2 MS/MS
• 9 Laboratories - benzoylecgonine
• 5 laboratories - cocaine
• Samples-
• Benzoylecgonine only Cycles 1, 2
• Cocaine benzoylecgonine Cycle 3

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Analysis of Cocaine Analytes Urine Summary

• Need special PT set to demonstrate adherence to
  proposed initial test cutoff of 150 ng/mL
• Need special PT sets to demonstrate precision and
  accuracy at 40 of proposed confirmatory cutoff
  of 100 ng/mL

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Analysis of Cocaine Analytes Hair Summary

• Initial Testing
• Additional PTs to demonstrate adherence to
  proposed cutoff of 1 pg/mg.
• Confirmatory Testing
• Variance of quantitative values still high. Some
  CVs over 60
• Washing did not appear to affect the means or the
  variance when compared to the non- washed
  quantitations

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Analysis of Cocaine Analytes Hair Summary
(continued)

• Confirmatory Test (cont)
• Additional PTs to challenge at and below the
  proposed cutoff for cocaine, benzoylecgonine,
  cocaethylene and norcocaine
• Additional PTs to investigate potential for
  conversion of cocaine to benzoylecgonine

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Analysis of Cocaine Analytes Oral Fluids Summary

• Initial Test
• Additional PTs to demonstrate adherence to
  proposed cutoff of 20 ng/mL.
• Confirmatory Testing
• Variance for cocaine approaching 20
• Variance for benzoylecgonine lt10 to gt60

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Analysis of Cocaine Analytes Oral Fluids Summary
(continued)

• Confirmatory Testing (cont)
• Additional PTs to investigate conversion of
  cocaine to benzoylecgonine
• Additional PTs to verify performance at and
  below proposed cutoff