Original Broadcast Date: Wednesday October 19, 2016

Online differential viscometers are commonly coupled to gel permeation chromatography (GPC) for molar mass determination via the Mark-Houwink-Sakurada relation, or alternatively the universal calibration technique. However, viscometry’s real strength is realized when coupled with multi-angle light scattering (MALS) to characterize size, shape, branching, and aggregation of polymers and biomolecules, providing deeper insight into macromolecular properties.

New developments in the technology of differential viscometers extend their capabilities to the realm of compact molecules such as proteins. Improved sensor technology in conjunction with a patented thermal balancing system allows for dramatically improved sensitivity and near immunity to pump pulses. We describe a new differential viscometer, incorporating these advances and others, that measures hydrodynamic radius with sensitivity exceeding that of online dynamic light scattering, especially for globular proteins and other compact macromolecules.

Learning Objectives:

  • How a new, high-resolution capillary bridge viscometer with enhanced thermal design increases sensitivity and dynamic range by more than 3x over previous generation instruments
  • How coupling online viscometry with MALS provides extended characterization of polymers and biomolecules
  • The extent of improvement to the determination of hydrodynamic radius and conformation of proteins afforded by the new instrument


Stepan Podzimek, Ph.D.
Department Head, Analytical and Physical Chemistry


Steven Trainoff, Ph.D. 
Chief Scientist
Wyatt Technology Corporation