ABSTRACT
During a typical IPC separation, a single IPR is present in the mobile phase, usually at constant concentration. The possibilities offered by the simultaneous presence of more than one hydrophobic ion in the mobile phase were recently investigated. An atypical concurrent use of both anionic and cationic IPRs yielded more efficiency and a shorter analysis time, probably because of the competition between the solute and the similarly charged IPR [1,2]. The same strategy adopted in the IPC separation of oxytetracycline and its marker residue in edible animal tissues was optimized using an excess of IPR oppositely charged to the analytes [3].
