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Jing et al.:
J
ournal of
AOAC I
nternational
V
ol.
98, N
o
. 5, 2015
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Table 11. Free versus total choline/carnitine in the SPIFAN matrix set
Choline (as OH, mg/kg )
Carnitine mg/kg
Dilute-injection (free)
MW digestion (total)
Dilute-injection (free)
MW digestion (total)
Product name
n
=
6
×
2
×
2
Avg.
RSD, %
n
=
6
×
2
×
2
Avg.
RSD, %
Free/
total, %
n
=
6
×
2
×
2
Avg.
RSD, %
n
=
6
×
2
×
2
Avg.
RSD, %
Free/
total, %
SRM1849a (
n
= 5)
902
1.6
1186
1.2
76
130
2.2
149
1.6
88
Infant powder milk
1345
2.1
1768
1.8
76
136
3.2
154
1.4
88
Infant powder soy
1463
2.5
2000
2.0
73
80.3
3.3
80.7
1.7
100
Infant powder milk
part hydrolyzed
1403
2.0
1873
1.8
75
80.2
2.2
103
1.7
78
Infant powder soy
part hydrolyzed
1490
2.1
1789
1.7
83
91.0
2.6
90.7
1.6
100
Adult powder low fat
1587
2.1
1819
2.3
87
1.6
84
3.4
46
48
Adult powder milk
37.2
17.0
423
3.2
9
0.5
140
0.7
56
66
Child formula powder
459
4.5
572
2.1
80
493
2.6
490
1.8
101
Infant elemental
powder
798
1.6
857
1.9
93
138
1.4
138
1.9
100
Infant RTF milk
141
1.5
243
2.1
58
26.2
2.0
26.8
1.6
98
Adult RTF high
protein
494
1.1
550
1.5
90
157
1.4
155
1.4
102
Adult RTF high fat
546
1.6
601
1.3
91
220
2.0
215
1.3
102
Table 12. Summary of daily carnitine and choline ion ratio (response at primary transition/response at confirmatory
transition): data averaged across analysts, free/total results, and sample types
a
Carnitine
TQD
TQS
Day
N
Mean
SD
RSD, %
Day
N
Mean
SD
RSD, %
1
37
2.061
0.042
2.02
1
19
0.609
0.009
1.52
2
37
1.999
0.037
1.87
2
19
0.608
0.012
2.02
3
37
1.858
0.030
1.64
3
19
0.587
0.006
1.10
4
37
1.654
0.040
2.44
4
19
0.588
0.007
1.17
5
38
1.862
0.050
2.66
5
21
0.617
0.019
3.06
6
37
1.874
0.035
1.88
6
21
0.631
0.019
3.00
7
37
1.842
0.031
1.69
7
18
0.648
0.008
1.24
8
37
1.820
0.024
1.34
8
24
0.670
0.024
3.55
9
37
0.624
0.006
0.91
10
37
0.627
0.005
0.78
11
38
0.632
0.010
1.55
12
37
0.638
0.004
0.61
Pooled
1.98
1.83
Choline
1
38
1.436
0.010
0.73
1
20
1.532
0.021
1.35
2
38
1.448
0.020
1.41
2
20
1.598
0.022
1.38
3
38
1.446
0.021
1.42
3
20
1.620
0.027
1.64
4
38
1.322
0.019
1.47
4
20
1.583
0.017
1.10
5
38
1.423
0.013
0.92
5
21
3.098
0.096
3.10
6
38
1.436
0.014
0.97
6
21
3.218
0.088
2.74
7
38
1.414
0.016
1.10
7
18
3.136
0.044
1.41
8
38
1.397
0.013
0.94
8
24
3.535
0.192
5.43
9
38
1.199
0.015
1.27
10
38
1.194
0.023
1.93
11
38
1.218
0.018
1.50
12
38
1.197
0.018
1.50
Pooled
1.15
2.27
a
Obtained during authors’ internal laboratory validation using other products, not the SPIFAN kit.
13