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Multi Laboratory Test – AOAC First Action Method 2012.22 Ascorbic Acid (Vitamin C) in Infant Formula and
Adult/Pediatric Nutritionals.
RDLS-RD150006
E. Campos Giménez (NRC, Lausanne)
Page 10
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Part 2. Multi Laboratory Test
Participation
to MLT
From the 24 laboratories that initially reported results for practice samples, two
of them did not receive the MLT samples due to Customs restrictions. The
remaining 22 laboratories reported valid data.
Results
Summarized results of the full MLT set of samples can be found in the Table
below. Full set of data is given in Annex H.
Requirements (SMPR 2012.012)
≤ 5 % ≤ 10 %
Sample
n
Mean
RSD
r
(%)
RSD
R
(%)
HorRat
Adult Nutritional RTF High Fat
21
17-6
4.2
11.3
1.54
SRM 1849a
17
8.1
3.5
3.7
0.45
Child Formula Powder
19
4-9
2.6
4.5
0.51
Adult Nutritional Powder Milk Protein Based
19
6.3
1.4
3.2
0.37
Infant Formula Powder Soy Based
17
10.3
1.6
6.0
0.75
Infant Formula RTF Milk Based
19
3.5
25.6
30.6
3.27
Adult Nutritional Powder Low Fat
21
11.0
31.8
33.0
4.19
Adult Nutritional RTF High Protein
18
19-7
1.7
9.3
1.29
Infant Elemental Powder
21
34-0
7.3
11.4
1.72
Infant Formula Powder Part Hyd Soy Based
22
19.5
2.4
8.0
1.11
n = number of laboratories (after outliers removal)
RSD
r
: relative standard deviation of repeatability
RSD
R
: relative standard deviation of reproducibility
Two samples showed much higher variability numbers than the rest (Infant
Formula RTF Milk Based and Adult Nutritional Powder Low Fat).
Ready-to-Feed products are much more sensitive to suffer from degradation
during storage, being most likely the reason why the RTF Formula showed
much higher than expected repeatability and reproducibility values. It was noted
by some participants that, in general, liquid products were no longer
homogeneous. Although most of the liquid formulas presented results within
acceptable ranges it might be desirable to exclude them from future testing.
Adult Nutritional Powder Low Fat showed a problem in either homogeneity of
the sample itself, storage spoilage or can mislabeling. Being unable to identify
the problem, it is proposed to disregard results on this particular sample.
In addition, no significant differences could be observed between laboratories
using HPLC or UHPLC conditions, provided that the suitability conditions
(separation of orotic acid from ascorbic acid) were respected.
Continued on next page
AOAC OMB Meeting Book
344