An automated mass photometer that measures 14 samples in an hour has been installed in our facility as part of the Turku Protein Core. The instrument will help in assessing the quality of macromolecules, especially proteins, their stability, aggregation, oligomerization stage, and molecular mass. It can be used prior to cryo-EM and crystallization studies to improve the quality of the proteins and to choose the right samples for structural studies (e.g., fractions with the desired protein-protein complex). The method requires only ng of sample (concentration range 100 pm-100 nM).