Chapter 28 — Chapter 28 — Chromatography

Simple mixtures can be separated by filtration, distillation and solvent extraction, but complex mixtures need advanced techniques. Chromatography is a versatile analytical technique that separates the individual components of a complex mixture based on their varying affinities for two different phases — a stationary phase and a mobile phase. It separates dyes in flowers, pollutants in water and medicinal extracts from leaves (e.g. leaf pigments: carotene, xanthophyll, chlorophyll a and b, pheophytin), and allows identification, purification and quantification with high precision in medicine, forensics and environmental science. Adsorption is a surface phenomenon in which particles accumulate only on the outer surface, e.g. activated charcoal adsorbs gases and impurities, so it is used in filters. Three important types: paper chromatography (PC), thin-layer chromatography (TLC) and gas chromatography (GC).