3.3.1 Thin-Layer Chromatography (TLC) Fingerprinting

Thin-layer chromatography fingerprinting compares the chromatographic profile of a test extract with that of an authenticated reference sample on a single...

Thin-layer chromatography fingerprinting compares the chromatographic profile of a test extract with that of an authenticated reference sample on a single silica gel GF254 plate, providing a rapid, low-cost, and visually interpretable method of both preliminary identity confirmation and constituent-class screening. Standard protocol applies a defined volume of sample and reference solution as discrete bands approximately one centimetre from the plate base, develops the plate in a pre-saturated, sealed chamber over a defined solvent system chosen for the target compound class (for example toluene:ethyl acetate:formic acid for polyphenols, or chloroform:methanol:water for alkaloids), and visualises the developed plate under ultraviolet light at 254 nm (where compounds absorbing UV appear as dark quenching spots against a fluorescent background) and at 366 nm (where certain compounds show characteristic fluorescence), often supplemented by spraying with a class-specific derivatising reagent.