The Zetasizer Nano ZSP is the premium system in the Zetasizer range. It is used for the measurement of size, electrophoretic mobility of proteins, zeta potential of nanoparticles and surfaces, and optionally the microrheology of protein and polymer solutions. The exceptional performance also enables the measurement of the molecular weight and second virial coefficient, A2, of macromolecules and kD, the DLS interaction parameter. The system can also be used in a flow configuration to operate as a size detector for Size Exclusion Chromatography (SEC) or Field Flow Fractionation (FFF).