title: Occurrence and behavior of system peaks in RP HPLC with solely aqueous mobile phases.
abstract: System peaks are important but often also disturbing phenomena occurring in separation systems. Behavior of system peaks was studied in reversed phase high performance liquid chromatography (RP HPLC) systems consisting of an RP Amide C16 column and aqueous solutions of organic acids with alkaline metal hydroxides as mobile phases. Binary mobile phases, composed of benzoic acid and lithium hydroxide (LiOH) or cesium hydroxide (CsOH), yielded two system peaks. The first peak was stationary and the second one moved with dilution of the mobile phase or with changes of the alkaline metal hydroxide concentration. The latter changes affected dissociation of the benzoic acid present in the mobile phase and thereby its retention. The presumption that the first system peak is not influenced by the type of alkaline metal cation and that it is related to the non-adsorbed component of the mobile phase was confirmed by a cyclic procedure. Three-component mobile phases composed of benzoic acid, tropic acid, and a hydroxide gave rise to three system peaks as expected. The first peak was again stationary and the two others shifted depending on the concentration variation of both acids. Resonance causing a zigzag peak, well described in capillary zone electrophoresis (CZE), was observed if 1-pentanol was injected into a chromatographic system with one-component mobile phase.
authors.affiliation: Faculty of Science, Department of Physical and Macromolecular Chemistry, Charles University in Prague, Prague, Czech Republic.
authors.forename: Kveta
authors.initials: K
authors.lastname: Kalíková
authors.forename: Vlastimil
authors.initials: V
authors.lastname: Hruska
authors.forename: Jana
authors.initials: J
authors.lastname: Svobodová
authors.forename: Richard
authors.initials: R
authors.lastname: Chudoba
authors.forename: Bohuslav
authors.initials: B
authors.lastname: Gas
authors.forename: Eva
authors.initials: E
authors.lastname: Tesarová