Retention behavior of a homologous series and positional isomers of aliphatic amino acids in hydrophilic interaction chromatography

Abstract

The retention behavior of several series of free α- and ω-amino acids and positional isomers of amino pentanoic acid in the hydrophilic interaction chromatography mode (HILIC) was studied. The study was carried out on three stationary phases followed by post-column derivatization with fluorescence detection in order to describe the retention mechanism of the tested amino acids. The effect of chromatographic conditions including acetonitrile content in the mobile phase, mobile phase pH (ranging from 3.5 to 6.5) and concentration of buffer in the mobile phase was investigated. The effect of the number of carbon atoms (nC) in aliphatic chains of the individual homologue of α- and ω-amino acids and the logarithm of the partition coefficient (logD) on retention was also a part of the presented study. A good correlation (r > 0.98) between the logk and logD values of amino acids or nC, respectively, was observed. The described linear relationships were subsequently applied to predict the retention behavior of individual members of the homologous series of amino acids and to optimize the mobile phase composition in HILIC. The obtained results confirmed that the retention mechanism of α-amino acids, ω-amino acids and positional isomers of amino acids was based on the logD values and the number of carbon atoms in the aliphatic chains of amino acids. The elution order of ω-amino acids and positional isomers of amino pentanoic acid was strongly dependent on the mobile phase pH in the investigated range whereas the retention factors of all α-amino acids remained essentially unchanged on all tested stationary phases.

Quantification of structurally related aliphatic amino alcohols in l‐valinol by hydrophilic interaction liquid chromatography separation combined with postcolumn derivatization and fluorescence detection

“…The order of retention of amino alcohols corresponded well to their log P values (Table ). Compounds with higher log P value are less hydrophilic and as a consequence less retained in HILIC mode .…”

“…The separation and quantitation of amino acids and amines including ethanolamine was carried out in a single run as their OPA/3‐mercaptopropionic acid or OPA/ N ‐acetyl ‐l‐ cysteine derivatives . One possible approach for separation of aliphatic amines, amino acids, and amino alcohols without precolumn derivatization step is HILIC [–].…”

Recent progress in the fundamental understanding of hydrophilic interaction chromatography (HILIC)

“…For example, Li et al investigated the retention mechanism of tetracyclines on an amino bonded silica phase and found that partitioning was a significant mechanism, especially in the range of 20-50% water, but adsorption and electrostatic interactions were also involved. 24 The elution order of the homologous amino acids correlated with the carbon number of the aliphatic chain, but no significant difference was observed when the retention data of both αand ω-amino acids was fitted to the partitioning and adsorption models. 23 More recently, Douša et al investigated the retention of a homologous series of aliphatic αand ω-amino acids on three polar stationary phases including an amide (TSKgel Amide-80), a diol (Kromasil 60-5DIOL) and an amino (Nucleosil 100-5 N(CH 3 ) 2 ) phase.…”

“…24 Chirita et al conducted an investigation on the retention mechanism by testing a large set of 76 compounds (anionic, cationic, neutral and zwitterionic) on two zwitterionic stationary phases (ZIC-HILIC and Nucleodur HILIC). Douša et al found a linear correlation (r > 0.99) between log k and log D for the α-amino acids at pH 3.5-6.5 and for the ω-amino acids at pH 3.5 on three polar phases (TSKgel Amide-80, Kromasil 60-5DIOL, Nucleosil 100-5 N(CH 3 ) 2 ).…”

Determination of nicotine and its metabolites accumulated in fish tissue using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry

“…A HILIC–MS method has the advantage of enhanced detection sensitivity and ESI efficiency due to its high organic content eluting solvent, which also provides low column backpressure because of low viscosity in mobile phase. HILIC can be a complementary alternative to separate highly polar compounds that are not retained or elute too early in RPLC .…”