Simultaneous determination of deuterated and non-deuterated alpha-tocopherol in human plasma by high-performance...

Labelled tocopherol is used to evaluate its absorption by biodiscriminating the dietary intake from the endogenous tocopherol pool of subject. A normal-phase high-performance liquid chromatographic method is described for the easy separation and quantification of deuterated (d(6)) and non-deuterated alpha-tocopherol. The alpha-tocopherol isotopomers were extracted from plasma triacylglycerol-rich lipoproteins in hexane, separated by two EC Nucleosil columns in series with a mobile phase of hexane-isopropanol (659.34:0.786, w/w) running isocratically. The detection of d(6)-alpha-tocopherol was performed by its UV absorbance at 297 nm with a limit of detection of 34 pmol/ml, a limit of quantification of 83 pmol/ml and a range of determination of 34-9905 pmol/ml. Between- and within-assay RSDs were 2.4% (n=10) and 2.7% (n=5), respectively.