SIMPLIFIED METHOD FOR VITAMIN-E DETERMINATION IN RAT ADIPOSE-TISSUE AND MAMMARY-GLANDS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A method for vitamin E (alpha-tocopherol) measurement in rat adipose t issue and mammary gland has been developed and validated. Tissues were homogenized in ethanol-water (1:1) and extracted with n-hexane. Vitam in K-1 was used as internal standard. Separation was performed by HPLC with methanol-water (96.5:3.5) as eluent in a Nucleosil C-18 column ( 15 x 0.46 cm) at 40 degrees C, Detection was by fluorescence with exci tation at 295 nm and emission at 350 nm for vitamin E and at 330 and 4 40 nm for vitamin K-1. Standards and tissue extracts were checked for linearity giving correlation coefficients over 0.99 in a range of conc entrations from 0.56 to 4.51 nmol/g in adipose tissue and from 2.18 to 17.4 nmol/g in mammary gland tissue. Intra-assay precision (R.S.D.) v aried between 3 and 4%, whereas inter-assay precision was between 8 an d 9%. Recoveries ranged between 95 +/- 3% and 98 +/- 11% for the two t issues, respectively. Vitamin E was measured in rats that had previous ly received one oral dose of this vitamin. Whereas vitamin E content i n adipose tissue did not differ between late-pregnant and virgin rats, it was significantly higher in mammary gland of pregnant rats, and th is difference could be related to the enhanced lipoprotein Lipase acti vity in this group. (C) 1998 Elsevier Science B.V. All rights reserved .