A bread-and-butter model was proposed to evaluate the weighing uncertainty of gas standard materials by combining the preparation principles of gas standard materials by using weighing method with the differential algorithms of multivariate function.The model was applied to calculate the content of CO in 10 μmol/mol CO standard materials prepared by weighing method and to evaluate its weighing uncertainty.The evaluation processes are simple and the result is reasonable.This modle is suitable for the evaluation of the uncertainty of gas standard materials in industrial processes.
