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FOR EXPERT REVIEW PANEL USE ONLY
NOT FOR DISTRIBUTION
1
Expert Review Panel for Infant Formula and Adult Nutrition
Evaluation of Method
2012.20
Title:
AOAC Official Method 2012.20 Choline in Infant Formula and Adult Nutritionals
Ion Chromatography and Suppressed Conductivity / First Action 2012
Author:
General comments about the method:
Consideration for Final Action Status
•
Performance Characteristics
-
Does the method meet the SMPR for the following:
Reproducibility (RSD
R
):
An MLT study was performed to characterize method precision, including reproducibility. Six
samples were studied, 3 powders and 3 liquids. SRM 1849A was not part of the MLT sample set.
The MLT protocol (as well as the original method 2012.20) appear to contain an error in the
preparation of the standard curve, where the lowest standard is prepared at 0.05 mg/L rather than
0.5 mg/L. Ultimately this probably had little effect on the results.
In general, the results produced by individual laboratories for the blind sample pairs were
consistent: all 6 samples met the RSD
r
criterion of ≤ 5%.
However, the results produced for the same samples across the different laboratories showed
much greater variation: of the 6 total samples, 3 did not meet the RDS
R
criterion of ≤ 10%,
producing values of 14%, 15% and 31%.
The data which was presented to the ERP also had an inconsistency: in the text, Appendix 1 it
indicates that for the sample type “Adult nutritional RTF High Protein”, samples “LHTK069 &
LKAU043” are duplicates, while in the associated spreadsheet, samples “LHTK069 & VFJL091” are
evaluated. Similarly, for the sample type “Adult nutritional RTF High Fat”, samples “VFJL091 &
YATV077” are duplicates, while in the associated spreadsheet, samples “LKAU043 & YATV077” are
evaluated. These samples had similar choline contents, and regardless of their grouping met the
SMPR requirements for RSD
r
and RSD
R
.
Recommendation:
I would not recommend this method for approval as a Final Action based on this data set.