HPLC WITH UV DETECTION FOR MEASUREMENT OF VITAMIN E IN HUMAN MILK

Abstract

SUMMARY Extraction of vitamin E from human milk, by use of hexane, with and without prior saponification, was compared. Analysis of milk extracts was performed by HPLC with a C18 column and UV detection. With both methods a significant relationship (P < 0.01) was obtained between levels of α-tocopherol and γ-tocopherol in human milk, although saponification resulted in higher and more consistent recovery of the internal standard, δtocopherol (99.6 ± 4.0%), and significantly improved the reliability of the data. The detection limit of the method (including saponification, extraction, and HPLC analysis) was 0.65 µg mL −1 δ-tocopherol in milk. The proposed saponification step was a simple modification of the method, because it was performed in the same tube as the extraction, took 30 min only, and did not involve use of an inert gas. The improved method was used to measure vitamin E in several milk samples.