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142
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ampos
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iménez
&
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artin
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J
ournal of
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nternational
V
ol
.
100, N
o
.
1, 2017
remaining 22 laboratories reported valid data. The full set of
original data is listed in Table 1, whereas the results of the
statistical evaluation are presented in Table 2. No significant
differences could be observed between laboratories using HPLC
(5) or UHPLC (6) conditions, when suitability conditions were
respected (i.e., the separation of orotic acid and isoascorbic
acid from ascorbic acid). In general, the precision results
(repeatability and reproducibility) were well within the limits
stated in
Standard Method Performance Requirement
(SMPR
®
)
2012.012 (8). Two samples showed much higher variability
(RSD>25%) than the SMPR. By excluding these values from
the statistical evaluation, repeatability ranged from 1.4 to 7.3%
and reproducibility from 3.2 to 11.4%. HorRat values were all
<2 (0.4–1.7).
These results were submitted to the AOAC Expert Review
Panel (ERP) in January 2015. Based on the aforementioned data,
the method was not recommended to move forward to Final
Action status because the high repeatability and reproducibility
values had been obtained in two samples [infant formula RTF
(milk-based) and adult nutritional powder (low-fat)].
Part 3
The ERP offered the method authors the opportunity to test
fresh samples from the new SPIFAN kit. Additional multi-
laboratory testing (MLT) on these two matrixes was therefore
organized (part 3).
Twelve laboratories agreed to participate in this study.
Two did not receive samples due to customs restrictions.
The remaining 10 laboratories reported valid data, which are
presented in Table 3.
After statistical analysis (
see
Table 4), the results for the
adult nutritional powder (low-fat) product were well within
Table 1. Full set of original data
a
Lab
No.
Adult nutritional
RTF (high-fat)
b
SRM 1849a
c
Child
formula
powder
Adult
nutritional
powder (milk
protein-based)
Infant formula
powder
(soy-based)
Infant
formula
RTF
(milk-based)
Adult
nutritional
powder
(low-fat)
Adult
nutritional
RTF
(high-protein)
Infant
elemental
powder
Infant formula
powder (part.
hyd.,
soy-based)
d
1 14.3 13.7 8.3 8.2 5.1 2.5 3.0 6.3 4.0 10.4 2.5 3.0 12.6 5.1 21.8 21.4 32.8 28.0 19.5 20.4
2 16.8 15.9 8.1 8.0 4.9 3.7 4.5 6.2 9.8 9.9 3.7 4.5 9.1 5.3 20.2 19.9 28.4 31.4 19.7 19.6
3 16.5 15.9 7.8 8.0 4.7 2.3 2.3 6.3 9.7 10.1 2.3 2.3 12.4 11.2 18.7 18.8 31.9 27.7 19.5 19.0
4 17.3 16.0 7.9 7.7 4.6 3.1 3.1 5.9 10.1 10.0 3.1 3.1 8.5 13.3 19.8 20.5 35.8 35.6 18.5 18.8
5 19.0 17.2 8.2 8.0 5.1 4.5 3.1 6.3 10.3 10.3 4.5 3.1 8.6 13.0 19.9 19.1 28.7 33.7 19.1 19.4
6 18.8 19.1 8.5 7.5 4.9 4.9 4.0 6.2 9.6 9.9 4.9 4.0 15.8 7.8 20.1 20.1 36.0 42.4 19.5 20.0
7 17.8 17.4 7.9 8.2 4.9 6.2 4.0 6.4 10.0 9.9 6.2 4.0 12.9 4.8 19.8 19.6 30.6 35.2 19.0 19.4
8 19.8 19.6 9.5 9.3 5.0 2.4 4.3 6.7 10.3 6.8 2.4 4.3 9.0 13.2 20.9 20.2 32.9 32.8 16.2 17.8
9 17.5 19.5 7.9 8.7 4.8 3.4 3.3 6.5 11.0 11.1 3.4 3.3 14.9 14.7 16.5 20.7 36.3 40.4 21.7 21.1
10 18.6 19.1 8.3 8.1 4.8 2.5 3.0 6.6 10.8 10.2 2.5 3.0 13.4 13.3 20.9 20.1 36.0 35.5 19.7 19.5
11 19.5 19.3 9.0 9.3 5.2 5.1 3.3 7.1 11.7 11.8 5.1 3.3 14.3 14.5 21.4 20.7 37.7 34.4 20.6 20.4
12 12.8 12.8 8.4 8.1 4.5 2.5 2.4 6.0 10.1 10.0 2.5 2.4 4.9 4.9 15.9 15.7 27.1 32.8 18.3 18.5
13 16.8 16.6 7.9 7.7 5.1 5.4 2.7 6.4 10.5 10.4 5.4 2.7 NA
e
NA 18.3 18.4 NA NA 19.2 19.7
14 15.1 16.7 7.8 7.7 4.8 3.5 1.8 6.4 9.2 9.1 3.5 1.8 14.9 15.9 16.3 16.8 32.1 33.7 17.8 18.8
15 20.4 21.4 8.3 8.5 5.3 7.2 5.1 7.4 11.7 10.2 7.2 5.1 14.8 11.9 24.0 23.2 41.1 40.6 22.3 24.0
16 19.4 18.4 8.5 8.2 5.1 2.9 4.5 6.7 10.9 11.0 2.9 4.5 13.8 5.8 20.4 20.3 36.8 32.0 20.7 20.6
17 NA NA 8.7 8.0 3.8 3.6 NA 6.1 7.8 8.4 NA NA 12.9 13.0 NA NA 37.6 36.2 15.9 16.4
18 19.1 19.5 8.5 8.4 5.3 3.0 2.9 6.0 10.7 10.5 3.0 2.9 9.3 14.0 21.9 18.9 36.9 37.5 21.4 21.2
19 17.2 18.4 6.9 7.7 4.9 4.5 3.6 6.4 10.3 10.7 4.5 3.6 12.9 3.1 20.5 18.2 34.1 31.7 20.1 19.9
20 19.1 18.2 10.1 10.0 5.8 2.2 2.3 7.3 9.3 11.4 2.2 2.3 13.0 7.2 19.4 19.4 36.6 32.7 21.0 20.8
21 16.0 17.9 7.3 NA 4.7 NQ
f
2.7 6.2 9.7 9.7 NQ 2.7 11.3 12.0 17.5 17.6 25.8 29.3 18.5 18.6
22 16.4 17.2 8.1 8.0 5.1 5.5 4.2 6.2 10.6 10.6 5.5 4.2 11.0 6.2 20.6 20.5 33.8 35.1 18.3 17.9
a
All results are in mg/100 g of reconstituted powder (25 g+200 g of water) or are as-is for RTF products.
b
RTF=Ready-to-feed.
c
SRM=Standard Reference Material
(www.nist.gov/srm).
d
part. hyd.=Partially hydrolyzed.
e
NA=Not analyzed.
f
NQ=Below the LOQ.
225