AOAC OMA# 2011.14 (Final Action Review)-OMB

Table 2011.14F. Interlaboratory study results for manganese Matrix Mean, mg/kg Rec., % S r a

RSD r

b , % S

R c , ng/g RSD R

d , % HorRat

No. of labs e Outlier labs f

Chocolate milk powder Dietetic milk powder 2

7.54 0.40

NA h

0.14 0.01

1.88 2.56 6.79 2.86

0.67

8.82 4.89 8.61 8.31

0.75 0.27 0.82 0.79

9 8 9 9

NS g

99

0.0197

2C NS NS

Infant cereal

16.74

NA 1.14

1.44 1.32

Peanut butter NIST SRM 2387 15.85 (16.0) i

99

0.45

Wheat gluten NIST RM 8418

12.87 (14.3) 1

90

0.23

1.75

1.13

8.75

0.80

9

NS

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.

minimize easily ionizable element (EIE) effects and to correct for physical and chemical interferences. F. Instrumentation ( Note : ICP-OES equipments must be used by qualified laboratory personnel who are familiar with the operation and maintenance of analytical systems and must follow manufacturer’s directions for safety risk, safety environment, and use of instruments.) ( a ) ICP-OES spectrometer .—Instrument with axial, radial, or dual view grating configurations and autosampler, capable of determining multiple wavelengths for each element of interest with the required sensitivity. A 3-channel peristaltic pump with or without appropriate in-line addition system (e.g., T connector) are linked between the peristaltic pump and nebulizer to avoid having to manually add ionization buffer and internal standards

to each sample solution. A thermostated cyclonic spray chamber equipped with a micro-concentric nebulizer or other components designed to optimize aerosol and maximize precision was used. Follow manufacturer’s recommendations. Select peristaltic pump rotation speed, sample, and internal standard pump tubes of similar size to maximize mixing accuracy while maintaining the required detection levels. Ionization buffer (cesium chloride) is combined with the internal standard solution to compensate EIEs effects (e.g., K, Na, and Ca) in the plasma since certain food materials can contain substantial concentrations of these elements. This provides a significant source of electrons in the plasma. The presence of ionization buffer in all samples and standards will minimize the effects of varying concentrations of EIEs in the sample. The solution presented to the nebulizer contains a maximum of 5000 mg/kg cesium for high-

Table 2011.14G. Interlaboratory study results for sodium Matrix Mean, mg/kg Rec., % S r a

RSD r

b , % S

R c , ng/g RSD R

d , % HorRat

No. of labs e Outlier labs f

Chocolate milk powder Dietetic milk powder 2

1927.84 1769.19 992.41

97 96 95

43.30 18.64 37.67

2.25 1.05 3.80

51.07 33.39 39.72

2.65 1.89 4.00 3.22

0.52 0.36 0.71 0.72

9 9 8 9

NS g

NS

Infant cereal

6SG

Peanut butter NIST SRM 2387 4924.12 (4890) h

101 158.61 3.22

158.61

NS

Wheat gluten NIST RM 8418

1346.82 (1420) h

95

19.56

1.45

26.85

1.99

0.37

8

6SG

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.

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