A certified reference material (CRM), NMIJ CRM 7512-a, was developed for the determination of trace elements in milk powder. At least three independent analytical methods were applied to characterize the certified value of each element; all of these analytical methods were based on microwave acid digestions and carried out using different analytical instruments. The certified value was given on a dry-mass basis, where the dry-mass correction factor was obtained by drying the sample at 65°C for 15 to 25 h. The certified values in the units of mass fractions for 13 elements were as follows: Ca, 8.65 (0.38) g kg
−1; Fe, 0.104 (0.007) g kg
−1; K, 8.41 (0.33) g kg
−1; Mg, 0.819 (0.024) g kg
−1; Na, 1.87 (0.09) g kg
−1; P, 5.62 (0.23) g kg
−1; Ba, 0.449 (0.013) mg kg
−1; Cu, 4.66 (0.23) mg kg
−1; Mn, 0.931 (0.032) mg kg
−1; Mo, 0.223 (0.012) mg kg
−1; Rb, 8.93 (0.31) mg kg
−1; Sr, 5.88 (0.20) mg kg
−1; and Zn, 41.3 (1.4) mg kg
−1, where the numbers in the parentheses are the expanded uncertainties with a coverage factor of 2. The expanded uncertainties were estimated considering the contribution of the analytical methods, the method-to-method variance, the sample homogeneity, the dry-mass correction factor, and the concentrations of the standard solutions for calibration. The concentrations of As (2.1 μg kg
−1), Cd (0.2 μg kg
−1), Cr (1.3 μg kg
−1), Pb (0.3 μg kg
−1), and Y (64 μg kg
−1) were given as information values for the present CRM.
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