VALIDATION OF A METHOD TO DETERMINE VITAMIN E (ALPHA TOCOPHEROL) FROM FEED INGREDIENTS BY HPLC USING REVERSED PHASE CHROMATOGRAPHY

Denisa Rachieru, R. Duca, Margareta Olteanu

Abstract
Keeping farm animals healthy is supported by feed quality. To prevent the high unsaturated fatty acids ingredients from getting rancid it is necessary to add antioxidants such as vitamin E (alpha tocopherol). EU and Romania regulations imposed special requirements on the performance of related laboratories on the validation of vitamin E determination in feeds according to the requirements of SR EN ISO/CEI 17025:2005 standard for the following performance categories: exactness, accuracy, repeatability, reproducibility, sensitivity, detection limit and quantification limit. The following results were obtained during the determinations on standard alpha tocopherol solution: exactness = 100.64 %, accuracy with RSD = 1.06% and 1.29%, repeatability with RSD = 1.06%, 0.62% and 0.74 %, reproducibility cu RSD 2.5% and 1.59%, sensitivity with R² = 0.998, the detection limit was lower than the quantification limit and within the admitted performance range. The model was tested on feed samples containing corn, rice, wheat, soybean meal, gluten used for layer feeding. The dietary vitamin E was calculated using the equation from the standardizing curve of the equipment obtaining 15 mg/100 g feed sample. Our work delivers to the specialists in feed quality control a tested model for the validation of the method to assay vitamin E from feed ingredients.

Key words: vitamin E, chromatography, validation, feed