Sl. Abidi et Tl. Mounts, NORMAL-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF TOCOPHEROLS ONPOLAR PHASES, Journal of liquid chromatography & related technologies, 19(4), 1996, pp. 509-520
Citations number
17
Categorie Soggetti
Chemistry Analytical","Biochemical Research Methods
Five plant tocopherols were separated by normal phase high performance
liquid chromatography (HPLC) on aminopropylsilica or diol-bonded sili
ca with fluorescence detection. HPLC characteristics of these compound
s were studied under various mobile phase conditions. Mobile phases em
ployed binary solvent systems comprising a hydrocarbon and an alcohol,
an ether or an ester. Separation factors (alpha) of adjacent ring-met
hylated tocol components were determined. Employment of aprotic weakly
polar modifiers in the mobile phases increased the or values for the
Fair of 5,8- and 7,8-dimethyltocol, but decreased those for the 5,7-an
d 5,8-dimethyltocol pair. Both component resolution and detection sens
itivity were adversely affected by the use of a diol-bonded silica pha
se of large particle size. HPLC with cyclohexane-binary eluents invari
ably led to lower values of analyte capacity factors (k') than with he
xane counterparts. Further, regardless of the type of column evaluated
, the tocol isomers eluted in an ethereal mobile phase in the order of
increasing k' values: k'(tetrahydrofuran) <k'(dioxane) < k'(t-butyl m
ethyl ether < k'(diisopropyl ether). In HPLC with protic co-solvents,
the observed differences in k' values among the three dimetyltocols we
re interpreted in terms of methyl substitution effects.