The Viscotek SEC-MALS 20 is a multi angle light scattering detector that can be used to measure the absolute molecular weight of proteins, synthetic and natural polymers, as well as molecular size expressed as the radius of gyration, Rg.

The SEC-MALS 20  is connected to the output of any SEC or GPC system, such as the Viscotek TDAmax. Signals generated from the sample passing through all detectors are analyzed by OmniSEC software. The SEC-MALS system consists of 20 detectors arranged around a vertical flow cell to detect scattered light at a wide range of angles.

The angular intensity and concentration information is combined to construct a plot, which is used in two ways. Firstly to extrapolate the data to determine the scattered light intensity at zero angle, from which the absolute molecular weight is calculated. Secondly to determine the initial slope of the plot which is related to the radius of gyration of the molecule (Rg). If the system configuration includes a viscometer, the combination of molecular weight and intrinsic viscosity data can be used to calculate the hydrodynamic diameter of the sample along with information on branching.

SEC system schematic  SEC-MALS 20 - Viscotek    SEC-MALS debye plot schematic

 Product  Technology
 SEC-MALS 20 web page  Static LS
 Viscotek web page  Multi Angle versus one angle