Malvern Viscotek TDAmax and Zetasizer nano ZSP for macromolecular characterisation

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Dynamic light scatting (DLS) and size-exclusion chromatography (SEC) are two commonly used analytical measuring techniques, typically used to measure molecule and nanoparticle properties such as size, molecular weight and stability. The techniques are fast, non-invasive and use minimal sample volumes.

Using traditional SEC with a single concentration detector to determine molecular weight requires creating a calibration curve of standards. This introduces inaccuracies, especially for proteins as the standards and samples will have different relationships between molecular weight, size, shape or hydrodynamic volume. Advanced multidetector SEC systems, such as the Malvern Viscotek TDAmax, include a light scattering detector to measure molecular weight without the need for column calibration.

The Viscotek system is a research-grade, temperature-controlled, multidetector SEC system combining light scattering, RI and intrinsic viscosity detectors. Intrinsic viscosity is a measure of molecular density and enables structural changes to be assessed. A combination of light scattering and intrinsic viscosity allows size (Rh) to be calculated. The addition of a UV photodiode array detector provides a wealth of additional compositional data.

The DLS system Malvern Zetasizer nano ZSP adds protein measurement and microrheology capabilities to the Zetasizer family. Recently designed, the DLS-based optical technique allows rheological characterisation of weakly structured and highly strain-sensitive materials using just 20 µL sample volumes. Among its applications are measuring the viscosity of polymer and protein solutions and determining the onset of protein aggregation. The product can also be used in flow configuration to operate as a size detector for SEC or FFF.