1.4.4 Chemical Authentication: Chromatographic Fingerprinting

Chemical authentication compares the chromatographic profile of a test sample against that of an authenticated reference drug, on the principle that the...

Chemical authentication compares the chromatographic profile of a test sample against that of an authenticated reference drug, on the principle that the qualitative pattern of secondary metabolites present is itself a reliable species-specific signature. Thin-layer chromatography (TLC) fingerprinting compares Rf values and spot patterns under UV light at 254 and 366 nm; high-performance thin-layer chromatography (HPTLC) fingerprinting extends this through densitometric scanning to yield a quantitative peak profile, a method now formally accepted by the Indian Pharmacopoeia as a mandatory identification test; and high-performance liquid chromatography (HPLC) is used to quantify a specific marker compound characteristic of the species, such as curcumin in turmeric or withanolide A in Ashwagandha. Many plant drugs additionally display characteristic fluorescence under ultraviolet light, a simple and rapid confirmatory character documented in official pharmacopoeial monographs.