Normand Cyr
Structural biology platform manager

Pascale Legault

Description of the technique

Size Exclusion Chromatography with Multi-Angle Light Scattering analysis (SEC-MALS) is an absolute technique for the determination of the molar mass and the average radius of gyration (Rg) of biomolecules in solution following a separation by liquid chromatography. The technique uses static diffusion of a high intensity light source through a solution containing macromolecules. The intensity of this diffusion is then detected under several angles, hence being able to calculate precisely the molar mass and the average radius of gyration (Rg).

Description of the equipment

Analytical chromatography (SEC)

An ÄKTAmicro (GE Healthcare) liquid chromatography system is used to perform a high resolution separation of macromolecules (proteins, RNA, DNA) at analytical levels. The precision of low flow rate pumps enables the use of analytical-grade chromatography columns and injection of small quantities of material to be analyzed.

Multi-Angle Light Scattering (MALS) Detector

A Dawn HELEOS II (Wyatt Technology) multi-angle light scattering detector is connected directly at the outlet of the chromatography column. The presence of multiple light scattering detectors enables the measurement of the light intensity at 18 different angles, offering great sensitivity (as low as 200 ng of BSA in solution) and both a wide range of molecular weights (200 Da to 1000 MDa) and of size (Rg 10 à 500 nm).

Refractive Index Detector (RI)

Finally, a OptiLab T-rEX (Wyatt Technology) refractive index detector is positionned downstream of the MALS detector in order to determine the concentration of biomolecules being separated.

Available chromatography columns

Several analytical liquid chromatography columns are available for SEC-MALS analysis.

Size-exclusion columns (SEC)

  • Superdex 200 Increase, 10×300
  • Superose 12, 3.2×300
  • Superdex 200 Increase, 3.2×300
  • Superdex 75, 3.2×300
  • Superose 6 Increase, 3.2×300

Ion-exchange columns (IEX)

  • Mono S, 1.6×5
  • Mono Q, 1.6×5


  • ASTRA (Wyatt Technology)