AOAC-RI ERP Micro June 2016

OMAMAN-29 A/ Collaboartive Study Manuscript OMA ERP June 2016 ERP Use Only

significant difference between the two methods, with a positive with a positive correlation in 1 data indicating more recovery of the target analyte by the candidate method. A dLPOD CP value 2 of 0.02 with 95% confidence intervals of (-0.10, 0.13) was obtained between presumptive and 3 confirmed results indicating no statistically significant difference between the presumptive and 4 confirmed results. 5 For the high inoculum level, 131 out of 132 test portions (POD CP of 0.99) were reported as 6 presumptive positive by the 3M MDA 2 – Listeria method with 132out of 132 test portions 7 (POD CC of 1.00) confirming positive. For samples that produced presumptive positive results on 8 the 3M MDA 2 – Listeria method, 131out of 132 samples confirmed positive (POD C of 0.99). 9 For test portions evaluated by the USDA/FSIS-MLG reference method, 132 out of 132 test 10 portions produced positive results. A dLPOD C value of -0.01 with 95% confidence intervals of 11 (-0.04, 0.02) was obtained between the candidate and reference method, indicating no 12 statistically significant difference between the two methods. A dLPOD CP value of -0.01 with 13 95% confidence intervals of (-0.04, 0.02) was obtained between presumptive and confirmed 14 results indicating no statistically significant difference between the presumptive and confirmed 15 results. 16 For the un-inoculated controls, 2 out of 132 samples (POD CP of 0.02) produced a presumptive 17 positive result by the 3M MDA 2 - Listeria method with 1 out of a 132 test portions (POD CC of 18 0.01) confirming positive. For samples that produced presumptive positive results on the 3M 19 MDA 2 – Listeria method, 1 out of 132 samples confirmed positive (POD C of 0.01). For test 20 portions evaluated by the USDA/FSIS-MLG reference method, 0 out of 132 test portions 21 produced positive results. A dLPOD C value of 0.01 with 95% confidence intervals of (-0.02, 22 0.04) was obtained between the candidate and reference method, indicating no statistical 23 significant difference between the two methods. A dLPOD CP value of 0.01 with 95% confidence 24 intervals of (-0.03, 0.05) was obtained between presumptive and confirmed results indicating no 25 statistically significant difference between the presumptive and confirmed results. 26 27 Detailed results of the POD statistical analysis are presented in Table 2016.2B and Figures 1C- 28 1D. 31 32 No negative feedback was provided by the collaborating laboratories in regard to the 33 performance of the 3M MDA 2- Listeria method. During the evaluation of the raw chicken breast 34 fillet, Laboratory 2 isolated Listeria innocua from an un-inoculated control sample. Since the 35 organism recovered was different from the inoculating organism, Listeria monocytogenes, no 36 just cause for removal of the data was determined and the data was included in the manuscript. 37 For the raw chicken breast fillet, Laboratory 10 reported isolating Listeria monocytogenes from 38 two un-inoculated control samples. The isolates were sent for further identification and it was 39 determined that they were the same strain as the inoculating organism, indicating that cross 40 contamination of the sample occurred. Due to the fact that cross contamination occurred, just 41 cause removal of the data was established and the data generated by Laboratory 10 was therefore 42 not included in the statistical analysis. 43 AOAC Research Institute Expert Review Panel Use Only 29 30 Discussion

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