Abstract
The Viscotek is a 20 angle multi-angle light scattering detector for the measurement of molecular weight and radius of gyration. It is designed for the characterization of natural, synthetic polymers and proteins. The hardware contains a number of technical advantages that place its performance above other MALS detectors.
Introduction
The Viscotek SEC-MALS 20 is a 20 angle multi-angle light scattering detector for the measurement of molecular weight and radius of gyration, Rg. It is designed for the characterization of natural and synthetic polymers and proteins. The hardware inside the SEC-MALS 20 contains a number of technical advantages that place its performance above other MALS detectors. This technical note briefly describes these advantages.Vertical flow cell with radial optics
The SEC-MALS 20 contains a flow-cell that is arranged vertically within the system. The chromatographic flow enters at the inlet at the bottom of the cell and flows upwards to the outlet. The laser is arranged horizontally so that the incident light passes through the center of the cell. The different detectors are arranged around the cell in the same plane as the laser. A schematic of this design is shown in figure 2 and the setup is known as a 'vertical flow cell with radial optics'.More angles
Whilst the number of angles in a MALS detector is not the primary factor in the accuracy of the data, it is a reasonably well accepted argument that the more angles a system contains, the more accurate the molecular weight will be. The reasoning behind this is that the more data points that can be plotted on the Debye plot, the more accurate the fitting will be. With 20 measurement angles, the Viscotek SEC-MALS 20 has more angles than any other system on the market for SEC enabling the most accurate data fits and the highest quality results. However, it is the accuracy of the extrapolation to 0° that ultimately leads to more accurately calculated molecular weight and Rg values and whilst more angles are important it is the lowest angles that are most important.
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