Determination of α-tocopherolquinone in human serum samples by liquid chromatography with fluorescence detection and on-line post-column derivatization

A HPLC/fluorescence method with on-line post-column derivatization by a photoreactor was developed, where alpha-, beta + gamma- and delta-tocopherolquinone (TQ) are separated on a 250 mm x 4.6 mm RP-18 column. The LOD is about 250 pg for all TQs. In combination with a two-step sample preparation procedure, this method was successfully employed for measurement of alpha-TQ in human serum samples. Recovery for a-TQ from spiked serum was excellent (99 +/- 5%) and results of alpha-TQ determinations in 111 serum samples are reported. Additionally, possibilities for determination of other TQs in serum and alternative derivatization with a zinc reduction column are discussed. (C) 2004 Elsevier B.V. All rights reserved.