title: Determination of vitamin E in human plasma by high-performance liquid chromatography.
abstract: The use of selective protein precipitation to enhance the recovery of vitamin E from plasma, by minimising binding with very-low-density lipoproteins, is reported. The procedure employed treatment of plasma with magnesium chloride and tungstate, followed by methanol protein precipitation. Separation of vitamin E was performed using reversed-phase high-performance liquid chromatography of the methanol extracts with subsequent UV detection of the compound. Using this technique the procedure was observed to be specific for vitamin E and linear over the range 1.0 to 40.0 micrograms/ml. The within-run imprecision (C.V.) at three different supplemented plasma vitamin E concentrations of 5.0, 10.0 and 20.0 micrograms/ml was 4.51, 3.33 and 2.58%, respectively, and the between-run imprecision (C.V.) estimated to be 5.19, 3.69 and 3.67%, respectively. With the same supplemented plasma vitamin E concentrations, the overall accuracy (bias) of the procedure, using an albumin matrix for calibration, was estimated to be 6.0, -5.0 and -3.5%, respectively, and the recovery of vitamin E from six different spiked plasma samples estimated to be 98.2 +/- 2.6%.
authors.affiliation: Clinical Innovations Ltd., Kenilworth, Warwickshire, UK.
authors.forename: J D
authors.initials: JD
authors.lastname: Cooper
authors.forename: R
authors.initials: R
authors.lastname: Thadwal
authors.forename: M J
authors.initials: MJ
authors.lastname: Cooper
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006801:Humans; D015636:Magnesium Chloride; D017973:Tungsten Compounds; D014810:Vitamin E / Q000097:blood*
chemical_list: D017973:Tungsten Compounds; D015636:Magnesium Chloride; D014810:Vitamin E; C025399:sodium tungstate(VI)