title: Selective chromatographic fractionation of catechol estrogens on anion exchangers in borate form.
abstract: The borate form of anion exchangers has been investigated for its utility in the field of estrogen analysis. The borate form of a weak (DEAE-Sephadex A-25) and a strong (QAE-Sephadex A-25) anion exchanger was easily prepared by appropriate washing of the gels, without the need of time consuming immobilization techniques. Estrogens with vicinal cis-hydroxyls were strongly retained in both gels through formation of borate complexes and readily separated from estrogens not possessing such groups. Moreover, borate complex formation with the labile o-dihydroxyphenyl moiety of catechol estrogens fully protected them from decomposition during chromatography. Quantitative recovery of catechol estrogens was thereby obtained without use of antioxidants. The borate form of QAE-Sephadex A-25 was capable, in addition, of separating estrogens not possessing vicinal cis-hydroxyls from the corresponding neutral steroids.
mesh_terms: D000837:Anion Exchange Resins; D001881:Borates; D002849:Chromatography, Gas; D002852:Chromatography, Ion Exchange / Q000379:methods; D002393:Estrogens, Catechol / Q000302:isolation & purification*; D007202:Indicators and Reagents
chemical_list: D000837:Anion Exchange Resins; D001881:Borates; D002393:Estrogens, Catechol; D007202:Indicators and Reagents