AOAC Final Action Methods in 2018

Table 2011.14I. Interlaboratory study results for zinc (Zn)

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

18.06 53.65 36.51

NA h 105

0.396

2.19 2.66 2.25 3.96 1.95

0.95 2.36 1.27 1.78 3.19

5.24 4.40 3.44 6.69 6.46

0.51 0.50 0.37 0.69 0.73

8 9 9 9 9

5SG

1.43 0.92 1.06 0.96

NS NS NS NS

Infant cereal

NA

Peanut butter NIST SRM 2387 Wheat gluten NIST RM 8418

26.64 (26.3) i 49.30 (53.8) i

101

92

Matrix extension (2017)

Mean, mg/100 g i

SRM 1849a Whole milk

15.2 (15.1)

101 ND j

0.559 0.013

3.69 3.57 3.04

0.8

5.26 5.27 8.17 67.2 11.3

0.70

12

0 2 1 2 2 2 1 0 1 1 0 1 1 2 1 2 2 1 0 2 2 0 1 3 1

0.375 0.357 0.127 0.788 0.066

0.02

0.4

9

Whole milk powder

ND 0.011 ND 0.008 ND 0.021

0.029 0.086 0.089 0.100 0.071 0.151 0.028 0.178 0.026 0.024 0.047 0.034 0.075 0.003 0.044 0.055 0.034 0.037 0.083 0.029 0.009 0.033 ND

0.62 4.36 0.96

10

Whey powder

6.1

9 9 6 9

Whey protein concentrate

2.63

Butter

ND ND

ND 0.1

ND 2.4

ND 4.8 9.4 5.9 6.2

ND

Cheese

2.4

0.48

Adult powder, low fat

0.748

ND 0.015 ND 0.034 ND 0.015 ND 0.058 ND 0.009 ND 0.006 ND 0.026 ND 0.02 ND 0.02 ND 0.002 ND 0.023 ND 0.014 ND 0.015 ND 0.028 ND 0.037 ND 0.012 ND 0.003 ND 0.009

2.05 1.32

0.8 0.6

12 11 11 12 11 11 10 11 10 10 12 10 10 12 11 5

Adult RTF, high fat

2.57 0.46 2.22

Adult RTF, high fat placebo

3.3

0.49

Adult RTF, high protein

2.61 3.09

7.99

0.8

Adult RTF, high protein placebo

0.289 0.161

9

0.66

Child milk powder placebo

3.5

14.9

1

Child milk powder

0.74

3.45 3.64

6.3 6.1

0.54

Child elemental powder Infant elemental powder

0.554

0.5

0.75

2.6

10 54

0.84 2.22 0.64 0.77 0.46 0.54 0.84 0.34 0.56 0.75

Infant elemental powder placebo

0.007 0.552

30.6 4.16 2.41 2.53 5.03 4.35 1.71

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

7.98

0.58

9.5 5.6 6.6 9.7

0.608 0.551 0.852 0.706 0.094 0.335

Infant powder milk Infant powder soy

Infant RTF milk

4.11

Infant RTF placebo

3.3 2.7

9

9

Toddler powder

9.9

11

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  NA = Not available. i  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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