High-performance thin-layer chromatographic determination of potato glycoalkaloids

A high-performance thin-layer chromatographic (HPTLC) method for the determ ination of the two main potato glycoalkaloids, alpha -chaconine and alpha - solanine, in different parts of the potato plant, is described. Samples wer e extracted with diluted aqueous acetic acid containing the ion-pairing rea gent 1-pentanesulfonic acid, sodium salt. Extracts were purified and analyt es fivefold concentrated by a solid-phase extraction (SPE) procedure using a Sep-Pak C-18 cartridge. The methanol SPE eluate was applied to the HPTLC silica gel 60 F-254 plates. The separation was performed in chloroform-meth anol-2% aqueous NH4OH (70:30:5) mixture as the mobile phase. Six different detection reagents: two modifications of the Dragendorffs reagent, phosphom olybdic acid, paraformaldehyde-phosphoric acid, Ce(IV)sulfate-sulfuric acid and sulfuric acid-ethanol reagents were applied for quantification by dens itometry. Fluorescence enabled detection of 10 ng of each alkaloid. (C) 200 0 Elsevier Science B.V. All rights reserved.