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Alpha-tocopherol was determined in feeds for chickens and pigs. Samples for chromatographic (HPLC) analysis were prepared using a method encompassing one-step extraction with a 30:70 (v/v) mixture of acetone: chloroform. The samples were eluted isocratically from a LiChroCARTTM 250-4 column with UV detection using a UV-VIS detector at a wavelength of 290 nm. The eluent was methanol at a flow rate of 1 ml/min. 20 ul samples were injected into the column using an autosampler. The retention time of the a-tocopherol acetate peak was 13.41 min with a coefficient of variation of 2.78%. The repeatability of the area under the curve, expressed as the coefficient of variation, was 22.7% for a-tocopherol concentrations ranging from 0.5 to 1 ug/ml, 8.3%> for a range from 1-11 fig/ml, and 1.8% for a range from 11 to 3000 ug/ml. The coefficient of variation for the full assay of a-tocopherol acetate in samples encompassing all of its stages, starting from the weighing of a sample to its chromatographic analysis, did not exceed 7.3%. The recovery of tocopherol measured against an external standard was 92.4%, and against a standard processed through the sample preparation steps 93.2%. Alpha-tocopherol acetate standard stored at 4°C and protected from the light was found to be very stable. Two of the advantages of the developed method are its speed and ease of performance.

Evaluation of HPLC method for the rapid and simple determination of α-tocopherol acetate in feed premixes