ViscoStar Differential Viscometer for GPC

The ViscoStar® is an on-line differential viscometer for GPC that measures the intrinsic viscosity (IV) of polymers. It is best used in conjunction with the DAWN® or miniDAWN® multi-angle light scattering (MALS) detectors in SEC-MALS-IV analysis to determine absolute molar mass, size, molecular conformation, branching ratio and Mark-Houwink parameters. 

The ViscoStar may also be used for traditional online IV applications, such as Universal Calibration or Mark-Houwink analyses of molecular weight and size, all supported by Wyatt’s ASTRA® chromatography software. 

The ViscoStar incorporates several innovations that make it the most advanced differential viscometer available: automated thermal bridge tuning to ensure perfect bridge balance every run, a patented pump pulse suppression system that eliminates pressure fluctuations due to the GPC pump without loss of chromatographic resolution, and dual-Peltier thermal control for optimal isolation of the temperature-sensitive bridge from room temperature variations.


  • Sensitivity: 100 ng of 100 kDa polystyrene in THF at 1 mL/min, with a standard 7.8 x 300 mm GPC column
  • Differential pressure noise: < 0.05 Pa
  • Differential pressure range: 6.9 kPa
  • Dynamic range: 135,000:1 for measuring small and large peaks simultaneously
  • Solvent compatibility: compatible with most aqueous and organic solvents
  • Capillary bridge autobalance: 10-min thermal, leak-free mechanism
  • Delay volumes: 8.1, 5.4 or 2.7 mL standard; 16.2 mL optional
  • Temperature control: 4 – 70 °C 
  • Touch-panel display for immediate access to data, diagnostics and settings
  • Software: ASTRA chromatography software provides comprehensive analyses and user-friendly features including HPLC control, “One-click MW” and user-designed reports. Optional 21CFR11 support for GMP.


  • Polymers: absolute molar mass and size (distributions and moments), conformation and branching, Mark-Houwink parameter determination
  • Linear or branched polymers, co-polymers 
  • Polymers not amenable to SEC-MALS analysis dissolved in semi-opaque or refractive-index-matched solvents, or polymers that fluoresce at the MALS laser wavelength
  • Most aqueous and organic solvents

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