AOAC ISPAM Stakeholder Panel Meeting Book 3-13-18

Quantitative Microbiology Validation Acceptance Criteria

ƒ Example 3: Method Developer Study for Multiple Matrices. • Two Level with a statistical difference according to workbook for different matrices

95% Confidence Intervals (LCL, UCL) (Log 10 ) -0.245 0.175 -0.200, -0.025 -0.257, 0.340 -0.1627, 0.5780 -0.0048, 0.1789 -0.0307, 0.0612 -0.1299, 0.1472 -0.0368, 0.0316 -0.0730, 0.1215 0.1288, 0.6960 -0.0988, 0.0602 -0.0699, 0.0073 -0.0132, 0.1601 -0.0852, 0.1654 -0.0664, 0.2310 -0.0330, 0.1181 -0.0557, 0.1181 -0.0068, 0.0812

Mean Difference a (Log 10 )

Contamination Level

Reference Method

Matrix

Low

-0.035 -0.512 -0.005 0.3703 0.0919 0.0152 0.0087 -0.0026 0.0242 0.5124 -0.0193 -0.0313 0.0866 0.0401 0.0823 0.0426 0.0312 0.0440

Poultry

FDA/BAM

Medium

High Low High Low High Low High Low High Low

Salad Dressing

Medium

FDA/BAM

Fresh Pasta

Medium

FDA/BAM

Ice Cream

Medium

SMEDP

Milk Powder

Medium

SMEDP

Milk

Medium

SMEDP

High

ƒ Example 4: Low Level of Contamination • How many replicates with “0” as the result is acceptable?

Matrix Method

Poultry

Alternative Method

Reference Method

Ct/g Log

Mean

SD Grubbs Ct/g Log Mean SD Grubb s

5 0.7853 3 0.6128 4 0.7076 6 0.8513 2 0.4914

0.6730 3 0.4771

#NUM! #NUM! #NUM! #NUM! #NUM!

0.5408 0

?

Low

0.6897 0.1421

0.1260 3 0.4771

#NUM! #NUM!

1.1369 0

?

1.3951 3 0.4771

ƒ Should the limit be the same for the alternative and the reference? ƒ i.e. is the data acceptable for the example above, but if it was reversed and the alternative method had 2 “0” data points, would that be acceptable?