171 / 596
1
Matrix Study Results
2
3
For each method, the probability of detection (POD) was calculated as the number of positive
4
outcomes divided by the total number of trials. [13] The following were calculated: the candidate
5
presumptive results, POD
CP
;
the candidate confirmatory results, POD
CC
; the difference in the
6
candidate presumptive and confirmatory results, dPOD
CP,
; the presumptive candidate results that
7
confirmed positive, POD
C
(=POD
CC
);
the reference method, POD
R
, and the difference in the
8
confirmed candidate and reference methods, dPOD
C
. POD analyses were conducted for the
9
MDA 2 -
Listeria
test points and compared to the appropriate reference method results. The pre-
10
validation target analyte background screen results and APC results are presented in Table 5. The
11
heat stress data for selected matrixes are presented in Table 6. The inoculum levels for each
12
environmental surface are presented in Table 7. A summary of POD analyses [14] are presented
13
in Tables 8-15. As per criteria outlined in Appendix J of the Official Methods of Analysis
14
Manual [15], fractional positive results were obtained for all matrixes.
15
16
Internal Study
17
18
Raw chicken leg pieces (25 g)
19
20
For the low inoculation level of the MDA 2 -
Listeria
assay, there were 4 presumptive positives
21
and 9 confirmed positives following the USDA/FSIS MLG 8.09 reference method confirmation
22
procedure resulting in 5 false negative samples. There were 5 observed positives for the
23
reference method. For the high inoculation level, there were 3 presumptive positives and 3
24
confirmed positives following the USDA/FSIS MLG 8.09 reference method confirmation
25
procedure. There was 1 confirmed positive following the reference method. Even though 5 false
26
negatives were confirmed, analysis show there to be no statistical difference when compared to
27
the reference method. Detailed results of the POD analyses are presented in Tables 8 and 12.
28
This matrix analysis was conducted using Demi Fraser with FAC brand X.
29
30
Raw chicken fillet (25 g)
31
32
For the low inoculation level of the MDA 2 -
Listeria
assay, there were 4 presumptive positives
33
and 4 confirmed positives following the USDA/FSIS MLG 8.09 reference method confirmation
34
procedure. There were 5 observed positives for the reference method. For the high inoculation
35
level, there were 2 presumptive positives and 2 confirmed positives following the USDA/FSIS
36
MLG 8.09 reference method confirmation procedure. There were 5 confirmed positives
37
following the reference method. Detailed results of the POD analyses are presented in Tables 8
38
and 12. This matrix analysis was conducted using Demi Fraser with FAC brand Z.
39
40
41
Bagged raw spinach
42
43
Compared to FDA-BAM
44
For the low inoculation level of the MDA 2 -
Listeria
assay, there were 6 presumptive positives
45
and 6 confirmed positives following the FDA/BAM Chapter 10 reference method confirmation
46
AOAC Research Institute
Expert Review Panel Use Only
OMAMAN-29 D/ PTM Validation Report 111501
OMA ERP - June 2016
ERP Use Only