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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