Sample Preparation: Making Pressed Pellets

Pressing a sample leads to a pressed pellet with a defined density thus ensuring reproducible sample preparation. For X-ray fluorescence analysis, it is important that the pellet is also mechanically stable because when being introduced into the analytical instrument, the sample is subjected to evacuation and then aeration after the measurement. High stability is required so that the sample does not break during these procedures. A few materials display this stability which can be increased by pressing in aluminum cups or rings. However, mixing with a binder is obligatory for most materials.