Isolation of suitable quantities –often up to milligrams level- is required to perform characterization.
Semi-preparative or preparative chromatography methods can be developed to isolate impurities or chemicals that cannot be achieved by other purification methods such as crystallization, or whose synthesis consisting in too many steps with low recoveries. In addition, bulk purification can be previously accomplished by Liquid-liquid extraction, purification on several open column types: silica gel (normal phase), C18 and C8 (reverse phase), Hypercarb for very polar molecules, size exclusion, ion exchange ….
Isolation of chemical compounds by preparative chromatography allows to achieve a pure standard of any unknown impurity besides structural elucidation and quantification can be perform by nuclear magnetic resonance and mass spectrometry means.