Asymmetrical flow field-flow fractionation (AF4)

SOLVE has two AF4 instruments which are used for analysis of peptides, proteins, nanoparticles, polymers, etc. The instruments are connected to MALS, dRI, FL and UV detectors as needed for the analysis.

(Image from Wahlund, K. G.; Nilsson, L. Field-flow fractionation in biopolymer analysis;
Williams, S. K. R., Caldwell, K. D., Eds.; Springer-Verlag: Wien, 2012, p 1.)

SOLVE utilizes AF4 instrumentation and detectors from the leading manufacturer Wyatt Technology.

Multi-angle light scattering detectors (MALS)

The MALS detectors are used in connection with an AF4 or SEC separation to directly determine the molar mass and size distribution of the analysed samples. Besides enabling size information of the sample to be obtained the MALS is also a highly sensitive detector of aggregates and particulates.

Differential refractive index detectors (dRI)

The dRI detectors are used in connection with the MALS detectors to enable the concentration to be determined. The detectors are especially useful for compounds that lack strong UV-absorbance.

Size exclusion chromatography (SEC)

The AF4 is used in combination with LC-chromatographs, which also can be used as standard LC-instruments for size exclusion chromatography (SEC) and RP-LC.

Dynamic light scattering (DLS)

The dynamic light scattering instrument (Dynapro Plate reader) gives information of size and size distribution of macromolecules and particles as well as determination of interaction parameters. While not showing as high resolution as AF4 or SEC, the method is comparably faster. The plate reader allows high throughput analysis and the temperature controlled sample compartment can be used for temperature stability studies to be performed in an automated and controlled fashion.


The Zeta-sizer allows determination of zeta-potential as well as size determination by DLS in batch mode.

Analytical centrifugation (AUC)

The analytical centrifugation instrument with UV absorbance optics allows size analysis of components at close to undisturbed conditions, i.e. with minimal influence from dilution or shear.