Determination of α-tocopherol in plasma by high performance liquid chromatography with fluorescence detection and stability of α-tocopherol under different conditions

In order to study the clinical effects of the antioxidant a-tocopherol (tocofersolan, CAS 30999-06-5) a simple, robust, sensitive and reliable high performance liquid chromatography (HPLC) method using fluorescence detection for the daily measurement of a-tocopherol concentration in plasma is described. Several methods of HPLC analysis using fluorescence techniques are published, however, investigations of the stability of alpha-tocopherol during sample preparation under different conditions are relevant in the routine measurements and have to date not been reported. Therefore a modified method, both sensitive and robust, qualified for the day-by-day measurement of a-tocopherol in plasma was established and the stability of a-tocopherol during sample preparation was analysed under different conditions. This method enables the complete separation of a-tocopherol from other compounds within 14 min. In addition, investigations on the stability of alpha-tocopherol during sample preparation showed the necessity of rapid sample preparation without delay. Prepared samples can be stored in liquid nitrogen for at least 56 days.