Micro December 2018

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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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