[Direct determination of diethylstilbestrol and its monoconjugates in plasma]

Direct Determination of Diethylstilbestrol and its Monoconjugates in Plasma After "homogeneous ion pair extraction" with CH3OH from plasma of patients suffering from metastatic prostate cancer and subsequent partitioning on a C18-phase diethylstilbestrol (E-DES) and its monoconjugates (glucuronide, sulfate) as well as its glucuronide-sulfate conjugate may be detected quantitatively by HPLC/UV (236 nm) or HPLC/ED (+1.0 V). Working electrode is a special home-made carbon paste electrode. The range of detection is in the low ng range (2-5 ng/ml plasma); standard deviation is less than 5%. It is the first time that plasma levels of these metabolites of fosfestrol (Honvan) could be measured directly without prior hydrolysis.