High-performance thin-layer chromatographic determination of potato glycoalkaloids

A high-performance thin-layer chromatographic (HPTLC) method for the determination of the two main potato glycoalkaloids, α-chaconine and α-solanine, in different parts of the potato plant, is described. Samples were extracted with diluted aqueous acetic acid containing the ion-pairing reagent 1-pentanesulfonic acid, sodium salt. Extracts were purified and analytes fivefold concentrated by a solid-phase extraction (SPE) procedure using a Sep-Pak C18 cartridge. The methanol SPE eluate was applied to the HPTLC silica gel 60 F254 plates. The separation was performed in chloroform–methanol–2% aqueous NH4OH (70:30:5) mixture as the mobile phase. Six different detection reagents: two modifications of the Dragendorff’s reagent, phosphomolybdic acid, paraformaldehyde–phosphoric acid, Ce(IV)sulfate–sulfuric acid and sulfuric acid–ethanol reagents were applied for quantification by densitometry. Fluorescence enabled detection of 10 ng of each alkaloid.