Denisa Rachieru


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

VALIDAREA UNEI METODE PENTRU DETERMINARE A VITAMINEI E (ALFA TOCOFEROL) DIN MATERII PRIME FURAJERE PRIN HPLC UTILIZĀND CROMATOGRAFIA CU FAZA INVERSA

Denisa Rachieru, R. Duca, Margareta Olteanu

Rezumat
Se stie ca in mentinerea sanatatii animalelor de ferma un rol important il joaca cantitatea si calitatea furajelor administrate. In cazul furajelor ce contin materii prime oleaginoase bogate in acizi grasi nesaturati, pentru a preveni rancezirea acestora este necesara adaugarea unui antioxidant cum este vitamina E (alfa tocoferolul). Legislatia UE si implicit a tarii noastre a impus cerinte speciale privind performantele laboratoarelor din domeniu prin validarea metodelor de analiza pentru alimente si furaje. Lucrarea prezinta un model experimental privind validarea metodei de determinare a vitaminei E (alfa tocoferol) din furaje stabilindu-se conform cerintelor standardului SR EN ISO/CEI 17025 :2005 urmatorii parametrii de performanta : exactitatea, precizia, repetabilitatea, reproductibilitatea, sensibilitatea, limita de detectie si limita de cuantificare. La determinarile efectuate pe solutie etalon de alfa tocoferol s-au obtinut urmatoarele rezultate : exactitatea = 100.64 %, precizia cu RSD = 1.06% respectiv 1.29%, repetabilitatea cu RSD = 1.06%, 0.62% respectiv 0.74 %, reproductibilitatea cu RSD 2.5% respectiv 1.59%, sensibilitatea cu R2 = 0.998, limita de detectie mai mica decat limita de cuantificare ; incadrandu-se in limitele de performanta admise. Experimentarea modelului s-a efectuat pe probe de furaj ce contin porumb, orez, grau, srot soia, gluten, utilizate in hrana gainilor ouatoare. In urma analizei, calculul vitaminei E din proba de furaj s-a efectuat utilizand ecuatia din curba de etalonare a aparatului obtinand 15 mg/100 g proba furaj. Prin prezenta lucrare se pune la dispozitia specialistilor care lucreaza in controlul de calitate a furajelor un model experimentat de validare a metodei de determinare a vitaminei E (alfa tocoferol), din materii prime furajere.

Cuvinte cheie: vitamina E, cromatografie, validare, furaje