Techniques for the determination of molecular weight, molecular size and molecular structure
Accurate determination of molecular weight is a key component of all macromolecular characterization experiments. For example, for proteins, accurate molecular weight determination will confirm the protein isolation/purification and degree of aggregation. For polymers, molecular weight is a fundamental determinant of many physical properties including stiffness, strength, viscoelasticity and toughness.
Malvern Instruments provides several powerful solutions for the determination of molecular weight, molecular size and molecular structure of all types of macromolecules – from the very rapid estimate of protein molecular weight using a few µL of sample to the complete characterisation of the molecular weight distribution and conformation of a complex polysaccharide or synthetic polymer.
Product options available:
Gel Permeation Chromatography/ Size Exclusion Chromatography (GPC/SEC) with Light Scattering
The Triple/Tetra Detector Array (TDA) is a chromatography detector used to measure absolute molecular weight at low angle and/or right angle. Fractionation of the sample occurs in the column and the full distribution as well as, Mn, Mw and Mz are measured to characterize fully the protein, polymer or macromolecule.
The Zetasizer series for protein solutions
The molecular weight of samples in solution can be estimated in a few seconds from a DLS measurement. The size measured by DLS can be fitted to a standard curve of molecule shape models to get an estimate of molecular weight. This quick measurement requires only a few microliters of solution and is well suited for protein screening applications.
Batch Static Light Scattering (SLS)
Molecular weight can be measured absolutely using the batch static light scattering technique. For this measurement, a range of known concentrations of a solution of the material are prepared and the scattering intensity of each measured. A Debye plot is used to calculate the molecular weight.