4. AOACRIMicroMethods-2018Awards

Table 2018.13B 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 c 95% LCL, UCL

Difference of Means b

Mean Log 10 CFU/g

Mean Log 10 CFU/g

s r

s r

Matrix

Lot

N a

s R

Lot

N a

s R

Uninoculate d

Uninoculate d

9

0.000

0.00

0.00

9

0.000

0.00

0.00

0.00

0.00, 0.00

Dry Pet Kibble

Low

9 9 9

1.616 2.583 3.359

0.28 0.09 0.09

0.34 0.19 0.16

Low

9 9 9

1.692 2.557 3.352

0.22 0.09 0.09

0.24 0.23 0.12

0.08 -0.03 -0.01

-0.09, 0.25 -0.12, 0.07 -0.10, 0.08

Medium

Medium

High

High

3M Petrifilm Rapid E. coli /Coliform Count Plate – E. coli (37 o C)

ISO 16649-5

Uninoculate d

Uninoculate d

9

0.000

0.00

0.00

9

0.000

0.00

0.00

0.00

0.00, 0.00

Dry Pet Kibble

Low

9 9 9

1.419 2.291 3.140

0.28 0.12 0.11

0.28 0.19 0.14

Low

9 9 9

1.542 2.296 3.202

0.22 0.11 0.16

0.22 0.17 0.21

0.12 0.01 0.04

-0.04, 0.29 -0.11, 0.12 -0.07, 0.16

Medium

Medium

High

High

3M Petrifilm Rapid E. coli /Coliform Count Plate – E. coli (42 o C)

Difference of Means b

Difference of Means c 95% LCL, UCL

ISO 16649-5

Uninoculate d

Uninoculate d

9

0.000

0.00

0.00

9

0.000

0.00

0.00

0.00

0.00, 0.00

Dry Pet Kibble

Low

9 9 9

1.400 2.342 3.133

0.27 0.13 0.14

0.27 0.15 0.14

Low

9 9 9

1.542 2.296 3.202

0.22 0.11 0.16

0.22 0.17 0.21

0.14 -0.05 0.05

0.02. 0.27 -0.15. 0.06 -0.09, 0.19

Medium

Medium

High

High

a Number of collaborators that reported complete results. b ADifference of means <0.5 indicates no statistically significant difference between m c 95% Lower and Upper Confidence Limits s r – Repeatability s R – Reproducibility

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