AOAC-RI ERP Micro June 2016

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

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Test Portion Analysis 2 3 Collaborators were instructed to follow the appropriate preparation and analysis as outlined in 4 the study protocol for each matrix for both the 3M MDA 2 - Listeria method and reference 5 method. For both matrices, each collaborator received 72 test portions (12 high, 12 low and 12 6 un-inoculated controls for each method to be performed). For the analysis of the deli turkey test 7 portions by the 3M MDA 2 - Listeria method, a 125 g portion was enriched with 975 mL of 8 Demi-Fraser (DF) broth, homogenized for 2 minutes and incubated for 24-28 hours at 37 ±1 o C. 9 For the raw chicken breast fillettest portions analyzed by the 3M MDA 2 - Listeria method, a 25 10 g portion was enriched with 475 mL of DF, homogenized for 2 minutes and incubated for 28-32 11 hours at 37 ±1 o C. 12 Following enrichment, samples were assayed by the 3M MDA 2 - Listeria method and, 13 regardless of presumptive result, confirmed following the USDA/FSIS MLG 8.09 reference 14 method. Both matrices evaluated by the 3M MDA 2 - Listeria method were compared to 15 samples analyzed using the USDA/FSIS MLG 8.09 reference method in an unpaired study 16 design. All positive test portions were biochemically confirmed by the API Listeria biochemical 17 test or by the VITEK 2 GPbiochemical identification test, AOAC Official Method 2012.02 [8]. 20 21 Each collaborating laboratory recorded results for the reference method and the 3M MDA 2 - 22 Listeria method on the data sheets provided. The data sheets were submitted to the study director 23 at the end of each week of testing for statistical analysis. Data for each matrix was analyzed 24 using the probability of detection (POD)statistical model [9]. The probability of detection (POD) 25 was calculated as the number of positive outcomes divided by the total number of trials. The 26 POD was calculated for the candidate presumptive results, POD CP, the candidate confirmatory 27 results (including false negative results), POD CC , the difference in the candidate presumptive and 28 confirmatory results, dLPOD CP, presumptive candidate results that confirmed positive (excluding 29 false negative results), POD C, the reference method, POD R , and the difference in the confirmed 30 candidate and reference methods, dLPOD C . A dLPOD C confidence interval not containing the 31 point zero would indicate a statistically significant difference between the 3M MDA 2 - 32 Listeria and the reference methods at the 5 % probability level. In addition to POD, the 33 repeatability standard deviation (s r ), the among laboratory repeatability standard deviation (s L ), 34 the reproducibility standard deviation (s R )and the P T value were calculated. The s r provides the 35 variance of data within one laboratory, the s L provides the difference in standard deviation 36 between laboratories and the s R provides the variance in data between different laboratories. The 37 P T value provides information on the homogeneity test of laboratory PODs [10]. AOAC Research Institute Expert Review Panel Use Only 18 19 Statistical Analysis

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