AOAC OMA# 2011.14 (Final Action Review)-OMB

2011.14 (MTE-01) MLT FOR ERP USE ONLY DO NOT DISTRIBUTE

180  P oitevin : J ournal of AOAC I nternational V ol . 95, N o . 1, 2012

Table 2011.14C. Interlaboratory study results for iron Matrix Mean, mg/kg Rec., % S r , mg/kg a RSD r , % b S R

, mg/kg c RSD R

, % d

HorRat No. of labs e Outlier labs f

NS g

Chocolate milk powder Dietetic milk powder 2

164.77

97

6.72

4.08 3.02 1.81 4.17

11.25

6.83 5.56 4.42

0.92 0.68 0.53 1.18

9 9 9 8

83.11 75.18

102 2.51

4.62 3.32 1.95

NS NS

Infant cereal

94 95

1.36 0.65

15.65 (16.4) h

Peanut butter NIST SRM 2387 Wheat gluten NIST RM 8418

12.45

6–C

49.29 (54.3) h

91

0.93

1.89

1.54

3.12

0.35

8

9–C

a  S r

= SD for repeatability (within laboratory).

b  RSD r

= RSD for repeatability.

c  S R

= SD for reproducibility (among laboratories).

d  RSD R = RSD for reproducibility. e  Reporting laboratories minus outliers.

f  C = Cochran outlier. g  NS = Not significant. h  Certified or reference values.

program close to that displayed in b ( 1 ). Wash the MDO glass volumetric flasks in a laboratory washing machine or soak overnight in a water bath with HNO 3 30% (v/v). Rinse with H 2 O to avoid or minimize risk of iron contamination. Dry MDC vessels at 60°C in drying oven for 1 h.

and collect the remaining filtrate for analysis. Note : Membrane disc filters (0.45 µm) are not recommended, as they are generally not metal-free. Transfer to polyethylene containers within 2 h. Dilute samples that are above the standard curve range or have total content of minerals higher than 1000 mg/L with H 2 O. Note : Final dilutions require the addition of appropriate amounts of HNO 3 for MDC digests (or appropriate amounts of combined acids for MDO) to maintain the proportion of 10% (v/v) HNO 3 (15%, v/v, combined acids and hydrogen peroxide) in the final solution to be analyzed. ( 2 )  Digestion vessel decontamination.— Decontaminate the used MDC digestion vessels with 5 mL HNO 3 according to a

Detection

E. Principle

Digested test solution or an appropriate dilution is presented to the ICP-OES instrument, which is calibrated with acid(s)-

Table 2011.14D. Interlaboratory study results for potassium Matrix Mean, mg/kg Rec., % S r , mg/kg a RSD r

, % b S R

, mg/kg c RSD R

, % d HorRat No. of labs e Outlier labs f

NS g

Chocolate milk powder Dietetic milk powder 2

8996.74 6443.79 6438.19

99 135.82 1.51 208.98 2.32 0.57 100 65.17 1.01 130.04 2.02 0.47 99 119.83 1.86 135.78 2.11 0.49 102 148.84 2.40 187.59 3.03 0.70

9 9 8 9

NS

Infant cereal

6–SG

6200.24 (6070) h

Peanut butter NIST SRM 2387 Wheat gluten NIST RM 8418

NS

411.08 (472) h

87

10.19

2.48

31.31

7.62

1.18

9

NS

a  S r

= SD for repeatability (within laboratory).

b  RSD r

= RSD for repeatability.

c  S R

= SD for reproducibility (among laboratories).

d  RSD R = RSD for reproducibility. e  Reporting laboratories minus outliers. f  SG = Single Grubbs outlier. g  NS = Not significant. h  Certified or reference values.