Comparison of chaotropic salt and ionic liquid as mobile phase additives in reversed‐phase high‐performance liquid chromatography of biogenic amines

Abstract

Highly hydrophilic compounds belonging to biogenic amines were analysed in the reversed-phase system, modified with the addition of ionic liquids: 1-ethyl-3-methyl-imidazolium hexafluorophosphate (EMIM PF(6)) and chaotropic salt NaPF(6) on Discovery HS C18 column at acidic conditions. The effect of the additives concentration and the presence of organic solvent on the analytes' chromatographic parameters such as retention factor, tailing factor and theoretical plates number were all determined. On the basis of k versus ionic liquid concentration in aqueous-organic mobile phase with constant amount of phosphate buffer, retention mechanism was studied. It was established that the presence of organic solvent with low dielectric constant and ionic liquid with both chaotropic ions allows achieving typical Langmuir shape of this relationship. Investigated mobile phase additives are comparable according to efficiency and selectivity towards biogenic amines analysis. However, the sensitivity was found to be better for the eluent system modified with chaotropic salt.

Ionic Liquids in Separation Techniques

“…This review focuses on experiments conducted by our group (Flieger, 2006;Flieger, 2009;Flieger & Czajkowska-Żelazko 2011a;Flieger & Czajkowska-Żelazko 2011b;Flieger & Czajkowska-Żelazko 2011c ) and described in the literature by others.…”

The influence of salt chaotropicity, column hydrophobicity and analytes’ molecular properties on the retention of pramipexole and its impurities

“…For the calculation of constant f, the change of the mobile phase ionic strength with the concentration of the added chaotrope was taken into account (see Eqs. (4) and (5) in [27]). Parameter c 1 corresponds to the retention factor of the analyte when no chaotropic agent is added to the mobile phase and these values were experimentally obtained.…”

“…Many efforts were made to elucidate its benefits in separation selectivity and efficiency of small molecules [1,2], ␤-blockers [3,4], different amines [5,6], antibiotics [7], alkaloids [8,9], phenothiazine and thioxanthene derivatives [10], and antiparkinsonian drugs [11][12][13]. Different models were put forward with the aim to rationalize analytes' retention behavior in such systems [1,[14][15][16][17].…”

Chaotropic salts in liquid chromatographic method development for the determination of pramipexole and its impurities following quality-by-design principles

“…The inorganic salts with chaotropic properties mimic the effect of classical amphiphilic ion-pair reagents, but due to their faster desorption from the stationary phase with increasing content of the organic modifier in the mobile phase, their use may be profitable for gradient organic modifier elution methods. Several groups of authors dedicated their investigation to the chaotropic approach both in terms of theoretical considerations of retention mechanism and practical advantages of its applicability [10][11][12][13][14][15][16][17][18][19][20][21]. However, there is no example in the literature dealing with the implementation of QbD concept to the method development when the chaotropic agents are concerned.…”