Liquid Chromatography and Fluorescence Detection of Vitamin A in Animal Feeds, Finished Feeds, and Premixes

Abstract

A simple liquid chromatographic method for vitamin A (retinol) in animal feeds is described. The feed is saponified, diluted to minimize interferences, and extracted Into petroleum ether with a single step. The analysis is sensitive and specific with liquid chromatography and a fluorescence detector. The minimum level of detection is 15 ng/mL, which Is equivalent to 10 000 units/lb vitamin A. The method Includes a stable and reproducible standardization of vitamin A that Is used to calibrate standard peak heights In terms of units retlnol/mL. Guarantees of 10 000 units/lb up to premix levels can be analyzed with good recoveries and precision.

Retinol determination in milk by HPLC and fluorescence detection

“…According to Thompson (1986) the casein and lactose contents of the alkaline digest do not affect the extractability of retinol. In agreement with Thorpe (1990), peak height produced a more linear calibration curve than peak area. Results and the regression line from the calibration curve are shown in Fig.…”