Improvement of peak shape in aqueous normal phase analysis of anionic metabolites.
The problem of poor peak shape for multiply charged negative-ion analytes under aqueous normal phase (ANP) conditions is investigated. Because less than adequate efficiency and symmetry can occur with a variety of mobile phases, gradients and additives, and to varying degrees depending on the instrument, sources other than solute/stationary phase interactions are more likely the cause. Since it is known that many of these compounds can interact strongly with metal ions, addition of a chelating agent to the mobile phase and/or the sample solvent was tested. In particular, ethylenediaminetetraacetic acid (EDTA) is a compound that forms strong complexes with most di-and tri-valent metal ions and can be used to verify whether trace amounts of these species are the source of the problem. In addition, the retention of a number of anionic compounds was measured at various concentrations of ammonium acetate and formate with EDTA in the mobile phase.
Department of Chemistry, San Jose State University, San Jose, CA 95192, USA. joseph.pesek@sjsu.edu
Joseph J
JJ
Pesek
Maria T
MT
Matyska
Steven M
SM
Fischer
D000838:Anions / Q000032:analysis / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000032:analysis* / Q000378:metabolism; D004492:Edetic Acid / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D007501:Iron / Q000032:analysis* / Q000378:metabolism; D013058:Mass Spectrometry; D017640:Silicates / Q000737:chemistry; D014867:Water / Q000737:chemistry
D000838:Anions; D017640:Silicates; C487012:silica hydride; D014867:Water; D003300:Copper; D004492:Edetic Acid; D007501:Iron