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AOAC RESEARCH INSTITUTE
AOAC
OFFICIAL METHODS OF ANALYSIS
(OMA)
OMAMAN-13: Determination Of Dietary Starch In Animal Feeds And Pet Food By An Enzymatic-
Colorimetric Method Collaborative Study*
Study Director: Mary Beth Hall, U. S. Department of Agriculture – Agricultural Research Service, U.S.
Dairy Forage Research Center, 1925 Linden Drive, Madison, WI 53706, USA
Precision
ER 1 Average RSDr 3.5%
ER 2
RSDr % = 1.23 - 8.61%
ER 3
Acceptable. Soybean meal was the highest but this was likely due to a possible lower degree of sample
homogeneity.
ER 4
See method collaborative study report.
ER 5
2-3% most samples; >8% Alfalfa pellets (low level @ ~1%); ~6% Dry Dog Kibble; 5% Soybean Meal (low
level @~1%)
ER 6
RSD(r) varies from 1.2 - 8.6 %, and is generally below 5% which I would generally regard as acceptable.
ER 7
good
ER 8
Good
Reproducibility
ER 1 Average RSDR 6.1%
ER 2
RSDR% = 3.87 - 11.16%
ER 3
Acceptable. Soybean meal was the highest but this was likely due to a possible lower degree of sample
homogeneity.
ER 4
See method collaborative study report.
ER 5
4-6% most samples; ~10% for Alfalfa pellets and Soybean Meal
ER 6
RSD(R) varies from 3.9- 11.2 %, and is generally below 6% which I would also consider acceptable.
ER 7
good
ER 8
Good
System Suitability
ER 1 Good systems suggested (Starch, sucrose, glucose)
ER 2
The use of corn starch as control sample to evaluative quantitative recovery in the assay.
ER 3
see above
ER 4
Definitely suitable for purpose
ER 5
N/A
ER 6
The use of enzymatic hydrolysis to convert starch to glucose, and the GOPOD assay to specifically assay
the starch means the method is very selective. Potential interferences have been identified and
suitable controls are mentioned.
ER 7
good
ER 8
Acceptable