Instrumental HPTLC determination of α-solanine and α-chaconine in peeled potato tubers

An HPTLC method has been used for quantification of glycoalkaloids (α-solanine and α-chaconine) in peeled potato tubers. The alkaloids were extracted with 1% acetic acid in deionized water containing 1-pentanesulfonic acid sodium salt, the extracted solutions were further cleaned by SPE on C 18 columns then analyzed by instrumental HPTLC with absorbance detection. Silica gel layers were used with chloroform-methanol-water-aqueous ammonia 70:30:5:0.5 as mobile phase. The chromatogram was dipped to the Ce(IV) sulfate derivatization reagent to reveal the spots of the glycoalkaloids and then scanned in absorbance mode at 505 nm. The RF values under these conditions were 0.07 for α-solanine and 0.14 for α-chaconine. The method was validated in accordance with International Conference of Harmonization guidelines for pharmaceutical analysis. Recovery was 80–90% for 20–100 mg kg −1 of the compounds in peeled potato tubers. The limit of quantification was 5.0 mg kg −1 for both α-solanine and α-chaconine. Repeatability, as average relative standard deviation, was 8.2% for α-solanine and 11.4% for α-chaconine. The concentration of these glycoalkaloids in peeled potato tubers from Czech retail outlets in 2004 and 2005 varied from 5.0 to 90.8 mg kg −1 for α-solanine and from 5.0 to 84.7 mg kg −1 for α-chaconine.