Asymmetrical Flow Field-Flow Fractionation (AF4)
Method Introduction
Asymmetrical flow field-flow fractionation (AF4) is a well-established and highly versatile technique for sizing and quantifying aggregates and particles in protein formulations.
AF4 separates the various species in a channel consisting of a non-permeable plexiglass upper wall and a semipermeable accumulation wall at the bottom made of an ultrafiltration membrane and a solid frit. In AF4, the so-called cross-flow, the underlying force to separate the species is a physical field directed perpendicular to the laminar flow of the mobile phase.
Similar to HP-SEC analysis, in AF4 analysis, UV, refractive index, and fluorescence detectors are usually used as concentration-determining/quantifying detection systems. Additionally, multi-angle laser light scattering (MALLS) detection is used to determine the molecular weight and size of separated species.
Applications
Because of its wide separation range from a few nanometers to several micrometers, AF4 has been found appropriate for analyzing colloidal systems, such as liposomes, nanoparticles, polymers and virus-like particles.
AF4 can be used in all stages of pharmaceutical development and manufacturing – from early research to late-stage release testing under GMP, serving as a valuable tool for the orthogonal cross-validation of high-performance size-exclusion chromatography (HP-SEC) and analytical ultracentrifugation (AUC). AF4 is often used in the context of forced degradation studies and real-time stability studies since those often imply the formation of relatively large amounts of aggregates in the size range covered by AF4.
Quality and Biosafety Level
We provide all our analytical services with the highest quality standards. Experienced scientists carry out each project, and a scientific reviewer comprehensively checks every report or data presentation.
We offer this technology with the following quality and biosafety levels:
R&D level
We offer this method under R&D. Our GRP system assures the highest-quality research standards.
Up to biosafety level 2
This method can be applied to nucleic acids, viruses, cells, viral vectors, including lentiviruses, and more.
Analytical Method Development, Qualification and Validation
For common sample types, we can often apply standardized methods with little setup effort. However, when needed, our experienced analytical experts create or optimize custom methods tailored to your active pharmaceutical ingredient, product type and development phase.
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