AOAC OMA# 2011.14 (Final Action Review)-OMB

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

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

Table 2011.14G. Interlaboratory study results for sodium 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

1927.84

97 43.30 96 18.64 95 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

Dietetic milk powder 2 1769.19

NS

Infant cereal

992.41

6–SG

4924.12 (4890) h 101 158.61 3.22

Peanut butter NIST SRM 2387 Wheat gluten NIST RM 8418

158.61

NS

1346.82 (1420) h 95

19.56

1.45

26.85

1.99

0.37

8

6–SG

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.

precision. 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 EIE 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-salted food raw materials (e.g., culinary products or tastemakers) and a minimum of 500 mg/kg cesium (for main food samples), 20 mg/kg indium and 5 mg/kg strontium, yttrium, and chromium, less than half of each element

concentration of the higher working standard Std6, and less than 0.5 g/kg total dissolved minerals. Power settings and nebulizer gas flow must be optimized to ensure that the Mg280.271:Mg285.213 ratio (Mermet principle of robust plasma) demonstrates robust operating conditions in accordance with the ratio established by the instrument manufacturer. At least three replicate readings of the same sample are performed, with relatively long integration times to minimize noise. ( b )  ICP wavelengths .—A number of recommended and alternative wavelengths may be used for the nine elements to be determined and internal standards. As a minimum, select one recommended and one alternative wavelength for each element corrected by one recommended wavelength for appropriate internal standard. All responses for both recommended and alternative wavelengths for each element are corrected

Table 2011.14H. Interlaboratory study results for phosphorus 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

NS f NS NS NS

Chocolate milk powder

4138.12

101 84.53 2.04 115.22 2.78 100 46.37 1.24 101.72 2.73 101 60.56 1.39 111.79 2.57 102 98.10 2.85 111.97 3.25

0.61 0.59 0.57 0.69

9 9 9 9

Dietetic milk powder 2 3729.50

Infant cereal

4341.81

3444.06 (3378) g

Peanut butter NIST SRM 2387 Wheat gluten NIST RM 8418

2050.02 (2190) g

94

37.86

1.85

67.15

3.28

0.65

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  NS = Not significant. g  Certified or reference values.