Micro December 2018
1
Table 2018.1B Interlaboratory Study Results of 3M Petrifilm Rapid E. coli /Coliform Count Plate vs. ISO 4832 & 16649-2
3M Petrifilm Rapid E. coli /Coliform Count Plate – Coliform (37 o C)
ISO 4832
Difference of Means b
Difference of Means c 95% LCL, UCL
Mean Log 10 CFU/g
Mean Log 10 CFU/g
Matrix
Lot
N a
s r
s R
Lot
N a
s r
s R
Uninoculated
9 9 9 9 9 9 9 9 9 9 9 9
0.000 1.616 2.583 3.359 0.000 1.419 2.291 3.140 0.000 1.400 2.342 3.133
0.00 0.28 0.09 0.09 0.00 0.28 0.12 0.11 0.00 0.27 0.13 0.14
0.00 0.34 0.19 0.16 0.00 0.28 0.19 0.14 0.00 0.27 0.15 0.14
Uninoculated
9 9 9 9 9 9 9 9 9 9 9 9
0.000 1.692 2.557 3.352 0.000 1.542 2.296 3.202 0.000 1.542 2.296 3.202
0.00 0.22 0.09 0.09 0.00 0.22 0.11 0.16 0.00 0.22 0.11 0.16
0.00 0.24 0.23 0.12 0.00 0.22 0.17 0.21 0.00 0.22 0.17 0.21
0.00 0.08 -0.03 -0.01 0.00 0.12 0.01 0.04 0.00 0.14 -0.05 0.05
0.00, 0.00 -0.09, 0.25 -0.12, 0.07 -0.10, 0.08 0.00, 0.00 -0.04, 0.29 -0.11, 0.12 -0.07, 0.16 0.00, 0.00 0.02. 0.27 -0.15. 0.06 -0.09, 0.19
Low
Low
Dry Pet Kibble
Medium
Medium
High
High
3M Petrifilm Rapid E. coli /Coliform Count Plate – E. coli (37 o C)
ISO 16649-5
Uninoculated
Uninoculated
Low
Low
Dry Pet Kibble
Medium
Medium
High
High
Difference of Means b
Difference of Means c 95% LCL, UCL
3M Petrifilm Rapid E. coli /Coliform Count Plate – E. coli (42 o C)
ISO 16649-5
Uninoculated
Uninoculated
Low
Low
Dry Pet Kibble
Medium
Medium
High
High
a Number of collaborators that reported complete results. b ADifference of means <0.5 indicates no statistically significant difference between methods c 95% Lower and Upper Confidence Limits s r – Repeatability s R – Reproducibility
2 3 4 5 6
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