6. AOACSPIFANMethods-2018Awards

13

Jing et al.: J ournal of AOAC I nternational V ol. 98, N o . 5, 2015  1405

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)

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, %

Product name

SRM1849a ( n = 5) Infant powder milk Infant powder soy Infant powder milk part hydrolyzed Infant powder soy part hydrolyzed Adult powder low fat Adult powder milk Child formula powder Infant elemental powder Infant RTF milk Adult RTF high protein Adult RTF high fat

902

1.6 2.1 2.5 2.0

1186 1768 2000 1873

1.2 1.8 2.0 1.8

76 76 73 75

130 136 80.3 80.2

2.2 3.2 3.3 2.2

149 154 80.7 103

1.6 1.4 1.7 1.7

88 88

1345 1463 1403

100

78

1490

2.1

1789

1.7

83

91.0

2.6

90.7

1.6

100

1587 37.2

2.1

1819

2.3 3.2 2.1 1.9

87

1.6 0.5

84

3.4 0.7

46 56

48 66

17.0

423 572 857

9

140

459 798

4.5 1.6

80 93

493 138

2.6 1.4

490 138

1.8 1.9

101 100

141 494

1.5 1.1

243 550

2.1 1.5

58 90

26.2 157

2.0 1.4

26.8 155

1.6 1.4

98

102

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.