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

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 column with UV detection. The eluent was methanol. Samples were injected into the column using autosampler. The repeatability of the area under the curve, expressed as the coefficient of variation was 22.7 percent for alpha-tocopherol concentration ranging from 0.5 to 1 micro gram/ml, 8.3 percent for a range 1-11 micro gram/ ml and 1.8 percent or a range 11 to 3000 micro gram/ml. The coefficent of variation for the full assay of alpha-tocopherol acetate in samples encompassing all of stages, starting from the weighing of a sample to its chromatographic analysis, did not exceeded 7.3 percent. The recovery of tocopherol measured against an external standard was 92.4 percent, and against a standard processed through the sample preparation steps 93.2 percent