Automated analysis for vitamin E in butter by coupling sample treatment continuous membrane extraction liquid chromatography with electrochemical detection

An automated procedure for the determination of vitamin E in samples of but ter with minimum sample manipulation has been developed. Following dissolut ion of the samples in a micellar medium (methanol-Triton X-100-water), on-l ine sample treatment involving alkaline hydrolysis is coupled with a separa tion and enrichment system in a cell containing a silicone membrane; the an alyte-rich phase is finally connected to a liquid chromatographic analytica l system - using a Cl8 column with electrochemical detection controlling th e whole system automatically. The proposed procedure has been successfully applied to the determination of vitamin E in samples of butter, using 2,2,5 ,7,8-pentamethyl-6-chromanol as internal standard. The coefficient of varia tion obtained was 6.7% for a inter-day assay. (C) 1999 Elsevier Science B.V . AU rights reserved.