AOAC Final Action Methods in 2018

Table 2011.14D. Interlaboratory study results for potassium (K)

Original validation (2011)

Matrix

Mean, mg/kg Rec., % s r a

RSD r

b , % s

R c , mg/kg RSD R

d , % HorRat

No. of labs e Outlier labs f

Chocolate milk powder Dietetic milk powder 2

8996.74 6443.79 6438.19

99

135.82 65.17 119.83 148.84

1.51 1.01 1.86 2.40 2.48 3.96 2.32 1.25 1.26 1.34 1.61 1.65 2.24 1.93 1.62 4.31 5.16 2.79 7.2 2.2

208.98 130.04 135.78 187.59

2.32 2.02 2.11 3.03 7.62

0.57 0.47 0.49 0.70 1.18 1.12 1.23 1.37 4.22 1.76 3.34 1.34 0.92 0.83 0.89 0.66 1.28 1.46 1.02 0.96 1.44 1.11 0.93 0.92 1.14 1.12 0.97 0.72 1.25 0.8

9 9 8 9 9

NS g

100

NS

Infant cereal

99

6SG

Peanut butter NIST SRM 2387 Wheat gluten NIST RM 8418

6200.24 (6070) h

102

NS NS

411.08 (472) h

87

10.19

31.31

Matrix extension (2017)

Mean, mg/100 g i

SRM 1849a Whole milk

932 (922)

101 ND j

36.9

42.1 10.2 9.73 287 57.6

4.52 6.49 7.46 15.4

12 11 11 11 11 10 10 12 12 12 12 12 11 12 12 10 12 10 12 12 12 12 12 12 12

0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 2 0 1 0 0 0 0 0 0 0

157 130

3.640

Whole milk powder

ND 1.63 ND 23.5 ND 10.6 ND 1.59 ND 0.73 ND 4.97 ND 2.9

Whey powder

1868 788 40.7 98.7

Whey protein concentrate

7.3

Butter

8.8 7.5 2.6 9.3

21.6

Cheese

7.6 5.9

Adult powder, low fat Adult RTF, high fat

44

222 177 150

4.18

Adult RTF, high fat placebo Adult RTF, high protein Adult RTF, high protein placebo Child milk powder placebo

ND

4

8

4.6 3.5

ND 2.91

5.27 4.47 0.82 6.06 3.49 4.73 4.26 2.79 5.09 5.38 4.59 7.2 4.5

98

ND

1.6

4.54 10.7

7.64 69.7 55.1 84.9 86.4 67.5 78.3 48.3 76.1 82.7 81.4 61.4 136

ND 0.329 ND 3.59 ND 1.53

Child milk powder

8.7

Child elemental powder Infant elemental powder

6.33

ND

1.3

1.5 2.1 1.3

5.6

Infant elemental powder placebo

ND 1.82

8.33

Infant PH powder milk Infant PH powder soy Infant powder FOS-GOS

ND

0.9

6.6

ND 2.04 ND 0.783 ND 2.66 ND 2.46 ND 0.859 ND 2.56 ND 2.41

2.61 1.62

5.44 5.78

Infant powder milk Infant powder soy

3.5

6.7 6.5

2.98

Infant RTF milk

1.055

5.63 4.39

Infant RTF placebo

4.18 1.77

2.7 9.2

Toddler powder

6.7

a  s r = Standard deviation for repeatability (within laboratory). b  RSD r = Relative standard deviation for repeatability. c  s R = Standard deviation for reproducibility (among laboratories). d  RSD R = Relative standard deviation for reproducibility. e  Reporting laboratories minus outliers. f  C = Cochran outlier; SG = Single Grubbs outlier; DG = Double Grubbs outlier. g  NS = Not significant. h  Value in parentheses = Certified or reference values. i  Results expressed as mg/100 g for ready-to-feed liquids as-is or reconstituted powders (25 g in 200 g water) or liquid concentrates (1:1 dilution by weight). j  ND = Not determined.

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