AOAC ERP MICRO AUGUST 2018

OMAMAN-44 B: Collaborative Study Protocol Expert Review Panel Use Only August 2018

target organism and the contamination levels. The expert laboratory data will not be

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used in the calculations.

6.6 The homogeneity of the sample will be analyzed according to the ISO/TS 22117: Annex B. The stability of the samples during transport will be tested after storage at 8°C for 24,

48, and 72 h.

6.7

Data Analysis and Reporting

6.7.1 For a detailed explanation of the quantitative method calculations to be

performed, see Appendix D (8).

6.7.2 Perform a logarithmic transformation on the reported CFU/g and outlier tests as described previously. Plot the candidate method result (x-axis) vs. the reference

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method result (y-axis). Usually major discrepancies will appear.

6.7.3 Construct a Youden plot. For a given matrix–level combination, plot replicate pairs as first replicate versus second replicate. Usually major discrepancies will be apparent: displaced means, unduly spread replicates, outlying values, differences between methods, consistently high or low laboratory rankings, etc.

6.7.4 Only valid data should be included in the statistical analysis.

6.7.5 Calculate repeatability (s r

) as the standard deviation of replicates at each

concentrations of each matrix for each laboratory.

6.7.6 Calculate reproducibility (s R

) as the standard deviation of replicates at each

concentration for each matrix across all laboratories.

6.7.7 Calculate mean difference between candidate and reference method

transformed results and its 95% confidence interval.

7.0 24 25 The validation study report is to be submitted by the method developer at the completion of data 26 collection. This report is to incorporate the results generated through the SLV and CS studies. The AOAC 27 Microbiology Expert Review Panel will review and determine if the method is acceptable for Official 28 Method SM First Action status. ERP Use Only Report 8.0 References 1. Official Methods of Analysis (2012), 20th Ed., Appendix J, AOAC INTERNATIONAL, 2. ISO/FDIS 16140-2:2016: Microbiology of the food chain — Method validation — Part 2: Protocol for the validation of alternative (proprietary) methods against a reference Gaithersburg, MD, http://www.eoma.aoac.org/app_j

method

3.

ISO 21528-1:2017 – Microbiology of the food chain -- Horizontal method for the detection and enumeration of Enterobacteriaceae – Part 1: Detection of

Enterobacteriaceae