Conventional size exclusion chromatography relies on reference standards that do not accurately represent your molecules. SEC-MALS measures molar mass directly, independent of elution time, for confidence in reported values.


Not all macromolecules behave alike. Your samples may have a different conformation than molecular standards or exhibit unexpected column interactions. As an absolute technique for determining molar mass and rms radius Rg in solution, SEC-MALS - the combination of Size Exclusion Chromatography with Multi-Angle Light Scattering analysis - overcomes the limitations of column calibration.

Standard in protein, biopolymer and synthetic polymer characterizations labs around the world, Wyatt MALS detectors are valued for reliable and robust measurements, delivered by our powerful ASTRA software.

Add one or more Wyatt detectors, MALS-certified SEC columns and software to your favorite analytical HPLC system in order to characterize:

  • Heterogeneous biopolymers and synthetic polymers
  • Oligomers and aggregates
  • Conjugates such as ADC PEGylated proteins or block co-polymers

Selected references

Folta-Stogniew, E. Oligomeric states of proteins determined by size-exclusion chromatography coupled with light scattering, absorbance, and refractive index detectors. Methods Mol. Biol.  2006, 328, 97-112.

Laurén, J.; Gimbel, D. A.; Nygaard, H. B.; Gilbert, J. W.; Strittmatter, S. M. Cellular prion protein mediates impairment of synaptic plasticity by amyloid-β oligomers. Nature  2008, 457, 1128-1132.

Ren, X.; Kloer, D. P.; Kim, Y. C.; Ghirlando, R.; Saidi, L. F.; Hummer, G.; Hurley, J. H. Hybrid structural model of the complete human ESCRT-0 complex. Structure  2009, 17, 406-416.

Tarazona, M. P; Saiz, E. Combination of SEC/MALS experimental procedures and theoretical analysis for studying the solution properties of macromolecules. J. Biochem. Bioph. Meth.  2003, 56, 95-116.

Zhang, M.; Zhang, L.; Cheung, P. C. K.; Dong, J. Fractionation and characterization of a polysaccharide from the sclerotia of Pleurotus tuber-regium by preparative size-exclusion chromatography. J. Biochem. Bioph. Meth.  2003, 56, 281-289.


Instrumentation for SEC-MALS

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.

Refractive Index Detectors

optilab t-rex, sec-mals, size exclusion chromatography, protein aggregation, polymer analysis, polymer molecular weight

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.


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.


ASTRA® - Our comprehensive software solution for MALS analysis in chromatography, AF4 or batch mode. ASTRA is available in a 21CFR(11) compliant version and offers additional options such as particle analysis. Provides multiple types of conformation analysis including conformation plots, Mark-Houwink-Sakurada parameters and shape factor.

"Most versitile SEC detector on the market - great product."
"I have been using MALS since the 1980's - Wyatt's have always been the best value. This latest is very user-friendly. The combined information from the MALS and the viscometry detector can't be beaten. Branched co-polymers are no problem; great for pH." Mary Baker, MCPS

"Without this lot quality control checks for the product would have not possible."
"This is the only technology available for absolute molecular size determination with ease of use. It is highly reproducible and recommended for polysaccharide and conjugate vaccine manufacturers." Rajendar Burki, Biological E Limited

"Great machine, one must have it in a lab for characterizing polymers."
"It is a fantastic MALS detector, easy to use and vary reliable. I have used/seen this detector in many labs, always happy to work with this MALS detector." Yonggang Liu, Changchun Institute of Applied Chemistry

"An absolute must for today’s protein biochemist"
"This instrument is perfect for understanding protein/detergent complexes and ascertaining the stoichiometry of protein/protein complexes. Wyatt also offer an excellent training course which is backed up by an excellent support team who are always on hand to help out." George Orriss, University of Manitoba

Interested in other techniques or combining other techniques with SEC-MALS?

FFF-MALS: Coupling an FFF system to a set of Wyatt MALS and/or DLS detectors creates a powerful system for accurate and robust characterization of molar mass and size distributions for simple or complex samples.

CG-MALS: Apply CG-MALS to characterize self- and hetero-association, binding affinity from pM to mM, absolute molecular stoichiometry (not just mole ratios) and more.

DLS: Measure the translational diffusion coefficients Dt of nanoparticles and colloids in solution by quantifying dynamic fluctuations in scattered light. DLS is suitable for ensemble measurements ranging from Rh values of 0.2 nm up to 5,000 nm.

MP-PALS: Wyatt Technology's breakthrough Massively Parallel Phase Analysis Light Scattering (MP-PALS) extends robust ELS measurements to proteins and other biomolecules in native buffer solutions. MP-PALS does everything conventional zeta potential instruments can do and much more.

SEC-IV: SEC-IV may be the optimal means of characterizing materials not amenable to SEC-MALS analysis. By simply adding a DAWN, transform a basic SEC-IV setup into a powerful SEC-MALS-IV polymer characterization station, to analyze absolute determination of molar mass and size regardless of conformation, branched polymers, copolymers and measure Mark-Houwink coefficients ab initio.