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B
ird
et al
.:
J
ournal of
AOAC I
nternational
V
ol
.
100, N
o
.
2, 2017
467
between presumptive and confirmed results, indicating that the
difference between presumptive and confirmed methods was
not statistically significant at the 0.05 probability level.
Detailed results of the LPOD statistical analysis are presented
in Table
2016.08D
and Figure 2.
Discussion
No negative feedback was provided by the collaborating
laboratories with regard to the performance of the 3M MDA
2 –
Listeria monocytogenes
method. For the raw chicken breast
fillet, Laboratory 10 reported isolating
L. monocytogenes
from
two uninoculated control samples. The isolates were sent for
further identification, and it was determined that they were
the same strain as the inoculating organism, indicating that
cross-contamination of the sample had occurred. Due to the
cross-contamination, just-cause for removal of the data was
established and, therefore, the data generated by Laboratory 10
were not included in the statistical analysis.
Overall, the data generated during this evaluation demonstrated
low reproducibility values, indicating that the method was
highly reproducible between laboratories. The within-laboratory
repeatability values indicated that the candidate method was
comparable to the reference method in terms of repeatability. For
the deli turkey analysis, the LPOD statistical analysis indicated that
the difference between the candidate and reference methods and the
difference between the presumptive and confirmed candidate results
were not statistically significant at the 0.05 probability level. For raw
Figure 1. (A) LPOD and (B) dLPOD values of candidate method versus reference method for deli turkey (125 g).