Liquid chromatography - Separation theory and methods

Liquid chromatography (LC) is a separation method based on the different modes shown in figure 1 (steric exclusion and chiral chromatography are the subject of separate articles in this treatise).

Liquid chromatography on columns has become a high-performance analytical tool used in a wide variety of fields, from the analysis of biological fluids to heavy petroleum products. This development is due to a better understanding of interaction mechanisms - which are becoming more and more diversified - to the high efficiencies obtained with ever finer stationary phases (3 µm), and to major advances in equipment, particularly for detection.

LC is therefore a complementary separation method to gas chromatography (GC) for the analysis of solutes that are not very volatile or thermodegradable (as is the case for most therapeutic molecules). It differs from GPC in the variety of stationary phases and hence interactions involved, and in its lower temperature, which increases the strength of these interactions and enhances selectivity.

On the other hand, PLC is a more delicate method to implement than GPC, and despite recent advances, it still suffers from the absence of detectors as sensitive and universal as GPC's flame ionization detection.