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[Development of the certified reference material of chromium in freeze-dried human urine].

OBJECTIVE
To develop the certified reference material in freeze-dried human urine.


METHODS
Normal human urine was collected, mixed and filtered as a matrix, then the urine was prepared by adding standard, mixing, sub-packaging, and freeze-drying; After the homogeneity and stability were tested by inductively coupled plasma mass spectrometer, the urine were determined by two methods in seven independent laboratories and the uncertainty of the certified reference material was evaluated.


RESULTS
The minimum sample intake of the developed certified reference material was 0.50 mL, and the homogeneity was good. The freeze-dried material was stable for 12 months at ≤4 ℃, and the reference material was stable at 4 ℃ after reconstitution for the 7 d. The standard value and uncertainty of the two levels were(16.0±1.0) μg/L and(30.7±2.1) μg/L(k=2), respectively.


CONCLUSION
The certified reference material of chromium in freeze-dried human urine in this research met the national certified reference material requirements and could be used for the quality control of the detection of chromium in laboratory human urine.