Wyatt Technology

Intrinsic viscosity analysis combines with light scattering for extended polymer characterization.


Intrinsic viscosity in conjunction with size exclusion chromatography (SEC-IV) has long been used by the polymer community to characterize molar mass. The two primary methods are Mark-Houwink analysis (using empirical values of Mark-Houwink coefficients from the literature) and Universal Calibration, which is appropriate for all linear, random coil polymers. Though these techniques are less rigorous than MALS, SEC-IV may be the optimal means of characterizing materials not amenable to SEC-MALS analysis:

  • When the solvent and solute have the same refractive indices (making dn/dc=0), the polymer does not scatter light
  • When the polymers fluoresce under excitation by the MALS laser, the fluorescence greatly increases the apparent scattering signal producing erroneous molecular weights. While a fluorescence blocking filter may be incorporated into the DAWN®, this does not always provide a sufficient solution to strongly fluorescing polymers.

The ViscoStar differential viscometer coupled with an Optilab differential refractometer to any GPC system provides superior measurements of intrinsic viscosity for characterization of all types of polymers. The ASTRA software not only analyzes polymers based on the Mark-Houwink equation and Universal Calibration technique but, with a MALS detector, can even calculate Mark-Houwink coefficients.

But these instruments can do much more! By simply adding a DAWN, transform a basic SEC-IV setup into a powerful SEC-MALS-IV polymer characterization station, to analyze from first principles:

  • Absolute determination of molar mass and size regardless of conformation
  • Branched polymers
  • Copolymers
  • Measurement of Mark-Houwink coefficients ab initio

Instrumentation for SEC-IV

  • Viscometer

    ViscoStar, sec-mals, size exclusion chromatography, protein aggregation, polymer analysis, polymer molecular weight

    ViscoStar® - A highly sensitive, on-line differential viscometer used in conjunction with SEC-MALS to determine the size and conformation of all types of biopolymers, synthetic polymers and even proteins and peptides.

    The ViscoStar incorporates multiple novel technologies to provide the highest sensitivity, stability and solvent compatibility of any available viscometer for GPC. Its ease-of-use and serviceability make it the perfect companion for Wyatt's DAWN® light scattering and Optilab® refractive index detectors. Temperature controlled from 4°C to 70°C.

    microViscoStar™ - Similar to the ViscoStar but designed specifically for use with UHPLC/APC.

    Refractive Index Detectors

    Optilab® - A unique on-line differential refractometer for measuring concentration of any macromolecule, regardless of chromophores. Temperature controlled from 4°C to 65°C. The high-concentration option accommodates protein concentration up to 180 mg/mL.

    microOptilab™ - The first RI detector specifically designed for use with all UHPLC systems.

  • MALS Detectors

    dawn-heleos-II, sec-mals, size exclusion chromatography, protein aggregation, polymer analysis, polymer molecular 

    DAWN® - The most sensitive MALS detector available, anywhere. Incorporates detectors at 18 angles to determine molar masses from 200 Da to 1 GDa and radii from 10 – 500 nm.

    • Standard option: ambient temperature
    • Heated/cooled option: -15°C to +150°C
    • High-temperature option: ambient to +210°C

    The DAWN offers special options to handle fluorescent samples: fluorescence-blocking filters and an infrared, 785 nm laser.

    - Second only to the DAWN in sensitivity. Incorporates detectors at 3 angles to determine molar masses from 200 Da to 10 MDa and radii from 10 – 50 nm. Ambient only.

    microDAWN™ - The first MALS detector for UHPLC, with interdetector dispersion as low as 1.5 µL. Incorporates detectors at 3 angles to determine molar masses from 200 Da to 20 MDa and radii from 10 – 50 nm. Ambient only.


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Wyatt Technology is the recognized leader in light scattering instrumentation and software for determining the absolute molar mass, size, charge and interactions of macromolecules and nanoparticles in solution.

Wyatt's line of multi-angle static light scattering products couple to size exclusion chromatography (SEC-MALS), field-flow fractionation (FFF-MALS), and stop-flow composition-gradient systems (CG-MALS). Our dynamic light scattering (DLS) products operate in traditional cuvette as well as on-line and automated, high-throughput modes. We also offer unique instruments for electrophoretic light scattering (MP-PALS), differential refractometry, and differential viscosity.

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