Molar Mass and Size via Light Scattering
Wyatt Technology revolutionized chromatographic analysis of macromolecules by making accurate measurement of molar mass via light scattering a practical reality. ASTRA brings that revolution to you tempered with decades of experience. Consider some of the features that tap into light scattering's full potential while making it easy to use:
The light scattering analysis view in ASTRA provides the tools to analyze your data easily. Molar mass and radius are instantly calculated and displayed for each slice. Slices can be selected directly from the chromatogram. The fit to the angular variation can be assessed on a slice-by-slice basis. In addition, individual detectors can be enabled or disabled, with instant feedback.
ASTRA supports several sophisticated models for analyzing the angular variation in the light scattering intensity to retrieve size information. Please see the section on particle analysis for details.
Light Scattering Instrument Support
Most other software packages that process light scattering data do not offer native support of light scattering instrumentation. Instead, they require that polymer standards be used to calibrate the instrument. This removes the fundamental advantage of light scattering to measure the molar mass directly, and instead ties light scattering to all of the weaknesses of column calibration.
ASTRA offers native support for light scattering instrumentation. Polymer standards are not needed to calibrate an instrument. Instead, a simple measurement of the fundamental scattering from a pure solvent is used to convert all further measurements into the native scattering units of Rayleigh ratio. No assumptions are necessary - in combination with a concentration detector, ASTRA measures molar mass directly.
Advantages of light scattering
Light scattering stands alone in its ability to measure the molar mass of macromolecules in solution both accurately and quickly:
- As opposed to mass spectrometry, light scattering can determine molar mass and aggregation state.
- As opposed to analytical ultracentrifugation, light scattering can measure molar mass and aggregation state in real time for fractionated samples.
- As opposed to column calibration, light scattering requires no outside standards, nor does it make any assumptions about how the sample elutes.
In addition to molar mass, light scattering also measures size. For more information on how light scattering works, please visit our Theory section.