[Development of the certified reference material of cadmium in human urine (freeze-dried)]

Objective: To develop the certified reference material of cadmium in human urine (freeze-dried) . Methods: Urine were collected from normal human, and then the urine samples were prepared by adding standard, mixing, packing and freeze-drying. After homogeneity test and stability test, the urine samples were determined by two methods in seven independent laboratories, the uncertainty of the certified reference material was evaluated. Results: Take at least 0.20 ml solution of the certified reference material per use, and the homogeneity is good. The freeze-dried materials can be kept stable for 12 months at ≤4 °C, and the re-dissolved reference materials can be stabilized for 7 days at 4 °C. The standard values and uncertainty of the two levels were (5.34±0.34) μg/L and (15.47±0.72) μg/L, respectively. Conclusion: The standards met the requirements of national standards, and can be used to verify the methods of detecting cadmium in human urine and to detect the samples.