A volume calibration phantom comprises a container; a plurality of plates stacking up inside the container; and at least one slab of radioactive source, each of which is disposed between the adjacent plates and comprises a plurality of radionuclides. The invention also relates to methods and devices for the classification and quantitative characterization of slow, as well as rapid separation phenomena of disperse material systems of different volume concentration. One polymeric additive comprises polyamide selected from the group consisting of poly-imino-bisalkylene-terephthalamide, -isophthalamide and -1,6-naphthalamide, and salts thereof.