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E
llingson
et al
.:
J
ournal of
AOAC I
nternational
V
ol
.
99, N
o
.
1, 2016
Table 3. Carnitine precision summary
a
Free carnitine
Total carnitine
Sample
Mean concn, mg/100 g RSD
r
, % RSD
INT
, % Mean concn, mg/100 g RSD
r
, % RSD
INT
, %
SRM 1849a
b
13.4
2.0
2.2
15.3
2.1
1.8
AN powder milk protein-based
<0.05
c
NA
d
NA
<0.05
NA
NA
IF hydrolyzed milk-based
0.909
1.8
2.1
1.21
4.4
4.8
IF hydrolyzed soy-based
1.05
1.8
3.0
1.04
1.6
2.2
AN powder low fat
<0.05
NA
NA
<0.05
NA
NA
Child formula powder
5.64
3.0
3.2
5.76
2.5
2.2
IF elemental powder
1.62
3.8
4.1
1.63
2.0
2.5
IF powder milk-based
1.59
2.1
2.1
1.82
2.7
4.7
IF powder soy-based
0.942
3.9
3.6
0.948
4.6
5.0
IF RTF milk-based
2.68
2.7
e
3.5
f
2.78
2.3
2.9
AN RTF high protein
15.5
3.6
3.9
15.7
1.9
1.7
AN RTF high fat
21.9
3.3
3.8
22.3
1.3
1.5
Child formula powder placebo
<0.05
NA
NA
<0.05
NA
NA
IF elemental powder placebo
<0.05
NA
NA
<0.05
NA
NA
AN RTF high protein placebo
<0.05
NA
NA
<0.05
NA
NA
AN RTF high fat placebo
<0.05
NA
NA
<0.05
NA
NA
IF RTF milk-based placebo
2.67
2.3
3.4
2.67
1.9
1.8
Overall
2.9
3.3
2.7
3.1
a
Samples were run in triplicate across 4 days,
n
= 12. Deviation is footnoted due to outliers by Grubbs’ test at a 95% confidence interval, loss of
sample during preparation, or failure to prepare in triplicate. Twelve data points were still obtained for all samples.
b
Free carnitine certified mass fraction mean and range of 13.6 mg/100 g and 12.2–15.0 mg/100 g, respectively.
c
Results below the SMPR-required LOQ of 0.16 mg/100 g and not included in the calculations.
d
NA = Not applicable.
e
One day of duplicates used for calculation.
f
Calculated across 5 days.
Table 4. Recovery analysis for choline
a
Free choline
Total choline
Sample
50% Overspike, % 100% Overspike, %
50% Overspike, %
100% Overspike, %
IF powder soy-based
97.6
97.0
98.4
99.6
AN RTF high protein
100.1
98.3
98.3
98.6
AN RTF high fat
NA
b
98.0
c
NA
99.9
c
,
d
IF RTF milk-based placebo
101.7
99.9
98.8
96.8
IF elemental powder placebo
95.9
e
NA
99.3
e
NA
a
Samples were run in duplicate over three days at each level,
n
= 6.
b
NA = Not applicable.
c
Samples were spiked at an amount that would achieve the upper range (250 mg/100 g) of the SMPR for choline.
d
n
= 5, due to loss of sample during a day of analysis.
e
Samples were spiked at an amount that would achieve the LOQ (2 mg/100 g) of the SMPR for choline.
Table 5. Recovery analysis for carnitine
a
Free carnitine
Total carnitine
Sample
50% Overspike, %
100% Overspike, %
50% Overspike, % 100% Overspike, %
IF powder soy-based
99.3
100.2
98.7
99.7
AN RTF high protein
102.4
103.6
101.5
102.7
IF RTF milk-based placebo
99.2
99.8
101.4
99.9
IF elemental powder placebo
102.5
b
NA
c
101.6
b
NA
a
Samples were run in duplicate over 3 days at each level, n = 6.
b
Samples were spiked at an amount that would achieve the LOQ (0.16 mg/100 g) of the SMPR for carnitine.
c
NA = Not applicable.
Candidates for 2016 Method of the Year
128