Chromatography is one of the most essential analytical tools in drug discovery, enabling scientists to separate, identify, and quantify the components of complex mixtures. Whether analyzing small molecules, peptides, biologics, metabolites, or impurities, chromatography provides the resolution and sensitivity needed to support every stage of pharmaceutical research. Chromatography separates molecules based on differences in:
Polarity
Charge
Size
Hydrophobicity
Affinity for stationary vs mobile phases
Major Chromatographic Techniques
1. Liquid Chromatography (LC, HPLC and UPLC)
Used for purity, identity, stability studies, and reaction monitoring
Supports UV, PDA, fluorescence, MS, and ELSD detection
Used for separating and isolating molecules dissolved in a mixture
2. Gas Chromatography (GC and distillation)
Ideal for volatile and semi‑volatile compounds
Simple distillation — large boiling point differences Fractional distillation — close boiling points Vacuum distillation — heat‑sensitive or high‑boiling compounds Steam distillation — isolating natural products or volatile oils
3. Size‑Exclusion Chromatography (SEC / GPC)
Separates molecules by size
Used for biologics aggregation analysis, polymer characterization, and formulation stability
4. Ion‑Exchange Chromatography (IEX)
Separates based on charge
Critical for charge variant analysis in proteins and peptides
5. Affinity Chromatography
Uses specific binding interactions
Central to protein purification and biologics manufacturing
6. Crystallization, Precipitation and trituration
May involve dissolving the crude solid in hot solvent, then cooling the resulting solution to allow pure crystals of desired molecule, then filtering and drying the purified molecule as a solid
Amenable to large scale purification of organic molecules
Removing impurities that remain soluble
7. Liquid–Liquid Extraction (LLE)
technique for separating compounds based on partitioning between immiscible solvents.