Microwave-assisted rapid determination of vitamins A and E in beverages

A new rapid procedure for the determination of vitamins A and E in beverages has been developed and validated. Key steps include a microwave-assisted saponification of the sample and a single-step extraction of the vitamins prior to HPLC analysis. All sample preparation steps are carried out consecutively in the same vial. The vitamins are determined using normal-phase (Si-60) HPLC with fluorescence detection. The method is applicable to beverages with a content of all-trans-retinol >0.14 mg/L and/or a content of alpha-tocopherol > 1 mg/L. Recoveries determined by spiking experiments ranged from 91.3 to 106.3%. The precision of the method is characterized by relative standard deviations of <2% for alpha-tocopherol and <5% for all-trans-retinol.