title: Liquid chromatography-tandem mass spectrometric analysis of ten estrogen metabolites at sub-picogram levels in breast cancer women.
abstract: The measurement of estrogens at sub-picogram levels is essential for research on breast cancer and postmenopausal plasma. Heretofore, these concentration levels have rarely been achieved. However, it is possible through derivatization but still represent problems for monitoring catechol estrogens and 16α-hydroxyestrone (16α-OH-E1). Estrogens possess poor ionization efficiency in MS/MS, which results in insufficient sensitivity for analyzing samples at trace concentrations. The method presented here was used to extract ten estrogen metabolites (EMs) with a derivatization step involving a new adduct. The electrospray ionization (ESI) MS/MS sensitivity for the EMs was enhanced by derivatization with 3-bromomethyl-propyphenazone (BMP). The lower limits of quantification (LLOQ) of the EMs were 12-100 femtogram on-column, equivalent to 0.3-3.6pg/mL plasma, and the limits of detection (LOD) were 0.1-0.8pg/mL plasma. The percentage coefficient of variation (CV%) at the LLOQ was <20 for all investigated EMs. Ionization suppression was minimized by reacting the excess reagent, BMP, with methanol. The method was successfully applied for the determination of ten EMs in the plasma of fifty healthy postmenopausal and fifty ductal breast cancer women aged 47-65 years old. 16α-OH-E1 and three catechol estrogen metabolites, 4-OH-E1, 2-OH-E2 and 4-OH-E2, were successfully measured in the plasma of healthy and breast cancer women. The methyl-propyphenazone-EM derivatives exhibited better sensitivity in ESI-MS (7.5-fold) compared to the commonly used dansylation procedure.
authors: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, P.O. Box 80260, Jeddah 21589, Saudi Arabia. Electronic address: akhedr@kau.edu.sa.
authors: Alaa
authors: A
authors: Khedr
authors: Department of Clinical Pharmacy, Faculty of Pharmacy, King Abdulaziz University, P.O. Box 80260, Jeddah 21589, Saudi Arabia.
authors: Abdulrahman M
authors: AM
authors: Alahdal
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000378:metabolism*; D002853:Chromatography, Liquid / Q000379:methods*; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D006801:Humans; D057230:Limit of Detection; D008875:Middle Aged; D052616:Solid Phase Extraction; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D004967:Estrogens
keywords: 3-Bromomethyl-propyphenazone; Breast cancer; Catechol estrogens; Derivatization; Estrogen metabolites; Liquid chromatography–mass spectrometry