Size exclusion chromatography (SEC), also called gel filtration, separates molecules by hydrodynamic size as they pass through a porous stationary phase. Larger species are excluded from pores and elute first; smaller species enter pores and elute later. In research peptide laboratories, SEC is a primary tool for assessing aggregation state and detecting high- and low-molecular-weight species that reversed-phase HPLC may not resolve.
How SEC Works in Peptide Workflows
A peptide sample is injected onto a column packed with porous beads calibrated for the peptide’s size range. Monomeric peptide, dimers/aggregates, and small fragments each produce distinct peaks. Analysts compare retention against molecular-weight standards and quantify peak areas to estimate the proportion of each species.
Applications in Quality Control
- Detecting soluble aggregates formed during synthesis, purification, or storage
- Confirming monomeric state before in vitro experiments where aggregation would confound results
- Monitoring stability studies alongside forced-degradation and accelerated-aging programs
- Complementing RP-HPLC purity data with an orthogonal, size-based method
Limitations and Good Practice
SEC resolution is lower than RP-HPLC, mobile-phase conditions can shift aggregation equilibria, and dilute samples may dissociate aggregates on-column. Laboratories therefore pair SEC with methods such as dynamic light scattering and mass spectrometry for a complete picture.
References
Hong et al., size-exclusion chromatography for protein/peptide aggregate analysis (analytical literature); USP general chapters on chromatography; ICH Q6B specifications guidance.
Disclaimer: This article is for laboratory research education only. All products referenced are not for human consumption / research use only. No medical, therapeutic, or dosing information is provided or implied.