A newly available application note from Malvern Instruments explains why, when measuring samples using Gel Permeation Chromatography/Size Exclusion Chromatography (GPC/SEC), low angle light scattering (LALS) is the only LS technique that actually measures a scattered light intensity directly proportional to molecular weight.
The application note "LALS or why closer is better", is free to download from Malvern's extensive knowledge base at: http://www.malvern.com/common/downloads/campaign/MRK1396-01.pdf
By avoiding the issues caused by data extrapolation or data fitting, which limit the alternative techniques of multi-angle light scattering (MALS) and right-angle light scattering / viscometry (RALS/viscometry), Malvern's state-of-the-art Viscotek LALS detector allows GPC/SEC practitioners to measure the molecular weight of their samples with certainty. In addition, the small size and simplicity of the LALS detector allows it to be used easily in integrated multidetector systems alongside viscometers, enabling the simultaneous determination of both molecular weight and molecular structure.