Assays - Tamoxifen

Specific high-performance liquid-chromatographic analysis of Tamoxifen and its major metabolites by "online" extraction and post-column photochemical reaction

Author: C. Kikuta, R. Schmid
Publisher: J. Pharm. Biomed. Analysis 7 (1989), 329-337

Plasma (0.8 ml) was mixed with 0.2 ml of 0.1M-HCl and then centrifuged for 2 min at 1200 g. For determination of tamoxifen (I) and demethyl-I, a portion (0.5 ml) of supernatant solution was applied to a pre-column (2.5 cm x 2 mm) of Sepralyte CN-propyl modified silica (40 µm) with H2O as mobile phase. The eluate was then applied to an analytical column (11 cm x 4.6 mm) of Partisil Si with a mobile phase of methanol - 5mM-ammonium acetate buffer (9:1). For the determination of 4-hydroxytamoxifen II, an analytical column (12.5 cm x 4 mm) of Lichrosorb RP-2 was used with a mobile phase of methanol - H2O - acetic acid - NN-dimethylhexamine (730:270:5:2). The separated compounds passed into a photoreactor (details given) and were converted into the corresponding phenanthrene by UV irradiation, and then detected fluorimetrically at 380 nm (excitation at 256 nm). The detection limits for I, demethyl-I and II were 100 pg/ml.