The influence of the Brazil nut effect

Sample material can be subject to the so-called Brazil nut effect. It occurs  for example during transportation: Depending on the density, shape, surface properties, orientation and external influences (e.g. kinetic energy), cavities are created for a short time which are occupied by small particles. Since the larger particles cannot occupy these cavities, they virtually migrate upward.

The inverse Brazil nut effect is the settling of the large particles towards the bottom of the sample.

Therefore, correct sampling methods are based on the principles of good laboratory practices and international standards. The goal is always correct sampling in order to minimize analysis variances.