Abstract
Estrogens and estrogen metabolites are important biological mediators of the endocrine system. They have also been implicated in detrimental carcinogenesis and beneficial neuroprotective processes. The retention behavior of estrogen metabolites was investigated on five polar stationary phases, used for hydrophilic interaction chromatography, and coupled with ESI-MS. Data were fit to partitioning and surface adsorption models. Retention of the compounds, especially estrogen glucuronides, on the amide- and diolbonded stationary phases, could be best described by the surface adsorption model; however, mixed modes of retention were observed on most stationary phases. Retention time increased while the peak efficiency decreased proportional to the number of hydroxyl groups in the analytes. The effects of salt concentration and salt type were also investigated. The presence of solvated salt ions, which interact with the stationary phase and the analyte, enhanced retention of the analytes. This was believed to be due to two effects. The increased ionic strength reduced the contribution of secondary electrostatic interactions (mixed-mode effects). It also enhanced hydrogen-bonding and partitioning (hydrophilic interaction) between the analyte and the stationary phase, likely facilitated by the associated solvated salt ions.
Original language | English (US) |
---|---|
Pages (from-to) | 793-802 |
Number of pages | 10 |
Journal | Journal of Separation Science |
Volume | 33 |
Issue number | 6-7 |
DOIs | |
State | Published - Mar 2010 |
Keywords
- ESI-MS
- Estrogen metabolites
- Estrogens
- Hydrophilic interaction chromatography
- Retention mechanisms
ASJC Scopus subject areas
- Analytical Chemistry
- Filtration and Separation