GC-MS method for detection of endogenous estrogens in urine samples

Breast cancer is the most common cause of death due to malignancy among women worldwide and the majority of the established risk factors are linked to estrogens as the case maybe the endogenous estrogen metabolism. The identification of specific alterations in endogenous estrogen metabolism as risk factor for breast cancer is a topic of extensive research. For simultaneus quantitation of all estrogens and estrogen metabolites of interest, an aforementioned gas-chromatography mass spectrometry method was optimised. After enzymatic deconjugation of estrogen conjugates using β-glucuronidase, solid-phase extraction on Sep-pak C18 columns and further sample purification by ion exchange chromatography on QAE-Sephadex cartridges in the acetat form, QAE-Sephadex cartridges in the borate form were used to separate estrogens into two fractions: one fraction containing estrogens without vicinal cis-hydroxyls and a second fraction containing estrogens with vicinal cis-hydroxyls (=catecholestrogens). After derivatisation estrogens were analysed by gas-chromatography mass spectroscopy in the selected ion monitoring mode.

The method shows a very well recovery (>96% for nearly all estrogen metabolites). Results for impresicion of the intra- and inter-assay variation are comparable low, what means that repetition is extremly good. Moreover the method is able to measure not only two estrogen metabolites like common ELISA tests but a multiplicity of metabolites. With a reduction in the number of steps and improvements according the work-up proceddures the new method is less complex and now useful for large study collectives.