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8
S
alvati
et al
.:
J
ournal of
AOAC I
nternational
V
ol
.
99, N
o
.
3, 2016
Table 4. Repeatability for six independent preparations is expressed as %RSD
Matrix
Total B
1
Total B
2
Total B
3
Total B
6
S01: 1849a
1.0
1.8
1.2
1.0
S02: Infant formula powder partially hydrolyzed, milk-based
0.7
1.7
1.6
1.5
S03: Infant formula powder partially hydrolyzed, soy-based
0.8
2.3
1.2
1.3
S04: Toddler formula powder, milk-based
1.2
2.8
1.0
4.2
S05: Infant formula powder, milk-based
1.1
2.3
1.3
1.1
S06: Adult nutritional powder, low-fat
1.8
3.8
1.7
1.5
S07: Child formula powder
1.6
2.6
1.3
0.8
S08: Infant elemental powder
0.6
2.6
0.6
1.6
S09: Infant formula powder FOS/GOS-based
a
1.1
2.6
1.0
0.8
S10: Infant formula powder, milk-based
1.0
2.3
1.0
1.1
S11: Infant formula powder, soy-based
0.9
1.4
1.0
1.2
S12: Infant formula RTF, milk-based
0.9
1.6
0.9
1.0
S13: Adult nutritional RTF, high-protein
1.8
2.4
1.9
2.9
S14: Adult nutritional RTF, high-fat
1.0
1.6
1.0
1.5
a
FOS/GOS = Fructo-oligosaccharides/galacto-oligosaccharides.
standards for good method precision and accuracy. Standard
addition is an alternative means to quantitate without stable-
isotope labeled internal standards, but was not evaluated in this
method because it is not practical when many different matrix
types are tested within a single run.
Despite the degree of signal suppression, ion ratio stability
between the two transitions was demonstrated to be good
across matrixes. For vitamin forms with modest signal intensity
(pyridoxine, thiamine, nicotinamide, and riboflavin), ion ratios in
the samples averaged 101 ± 3% of the ion ratio in the standards.
Table 3. Accuracy is expressed in terms of the average over-spike recovery in select matrixes
Matrix
Total B
1
Total B
2
Total B
3
Total B
6
%Rec
a
%RSD
%Rec
%RSD
%Rec
%RSD
%Rec
%RSD
Adult nutritional RTF, high-fat; placebo
Low QC
94.9
4.9
97.2
1.6
102.1
7.8
100.2
3.2
High QC
93.4
5.7
95.5
1.7
103.1
6.8
99.5
2.7
Adult nutritional RTF, high-protein; placebo
Low QC
97.7
4.3
96.5
2.2
101.6
5.9
96.8
2.4
High QC
95.4
5.5
98.4
2.7
102.9
3.8
98.8
2.7
Child formula powder, placebo
Low QC
99.0
5.7
98.0
2.7
105.4
6.3
99.7
1.8
High QC
97.0
7.0
98.9
2.8
105.7
5.3
99.1
1.9
Infant elemental powder, placebo
Low QC
93.7
6.4
95.1
1.8
104.5
6.8
97.9
2.1
High QC
92.4
7.8
96.7
1.0
103.8
4.9
98.4
3.4
Infant formula powder partially hydrolyzed, milk-based
Low QC
100.5
1.9
100.2
1.6
103.8
1.2
99.1
1.5
High QC
101.3
1.8
100.0
2.4
111.7
1.7
100.1
2.9
Infant formula powder partially hydrolyzed, soy-based
Low QC
100.7
1.5
100.7
2.1
102.0
0.9
99.3
0.9
High QC
103.1
0.6
99.6
2.0
106.7
1.1
99.8
2.4
Infant formula powder, soy-based
Low QC
99.3
1.4
95.7
4.4
101.1
1.7
98.9
1.3
High QC
96.6
3.4
96.8
2.9
100.1
2.9
97.2
2.0
Infant formula RTF, milk-based; placebo
Low QC
96.9
4.3
100.7
1.8
105.3
5.7
98.6
2.8
High QC
95.5
6.1
97.9
3.2
103.3
6.9
99.6
3.8
A cocktail including all vitamin forms listed in the SMPRs was spiked at approximately 50 and 200% of the fortification level.
a
%Rec = Percent recovery.
112