Determination of estramustine phosphate and its metabolites estromustine, estramustine, estrone and estradiol in human plasma by liquid chromatography with fluorescence detection and gas chromatography with nitrogen-phosphorus and mass spectrometric detection

Bioanalytical methods for the determination of estramustine phosphate by li quid chromatography and its four main metabolites estromustine, estramustin e, estrone and estradiol by gas chromatography are described. For the estra mustine phosphate assay the plasma was purified by protein precipitation fo llowed by a C-18 solid-phase extraction. For the metabolite assay the plasm a samples were purified by a C-18 solid-phase and liquid-liquid extraction procedure and derivatised by silanization. Thereafter, estramustine and est romustine were quantified by gas chromatography with nitrogen-phosphorus de tection and estradiol and estrone were quantified by gas chromatography wit h selected ion monitoring. The methods were validated with respect to linea rity, selectivity, precision, accuracy, limit of quantitation, limit of det ection, recovery and stability. The limit of quantitation was 2.3 mu mol/l for estramustine phosphate, 30 nmol/l for estromustine and estramustine, 12 nmol/l for estrone and 8 nmol/l for estradiol. The results showed good pre cision and accuracy for estramustine phosphate and the four metabolites. Th e intermediate precision was 6.2-13.5% (C.V.) and the accuracy was 91.8-103 .9%. (C) 2000 Elsevier Science B.V. All rights reserved.