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 α-, β + γ- and δ-tocopherolquinone (TQ) are separated on a 250 mm × 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 α-TQ in human serum samples. Recovery for α-TQ from spiked serum was excellent (99 ± 5%) and results of α-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.