RESUMO
Objective: To explore the feasibility of using drawing ball model to predict the minimum sampling mass of powders. Methods: A drawing ball model was established by abstracting the particle of powders as small balls. Then the minimum sampling mass which representing the measured powders was calculated by the model. Microcrystalline cellulose (MCC) and starch were used as model powders and then the particle size distribution curves of them were determined at different sampling mass of 5, 10, and 100 mg. The homogeneity of samples was judged by the coincidence of the particle size distribution curves. Results: According to the drawing ball model, the minimum sampling mass of MCC was more than 5 mg and that of the starch was less than 5 mg, which were consistent with the results of verification experiment. When the sampling mass was 100 mg, it could also represent the overall MCC. Conclusion: Drawing ball model is feasible to investigate the minimum sampling mass of powders. The smaller the particle size of powders is, the less the minimum sampling mass would be.