Separation of highly charged (+5 to +10) amphipathic α-helical peptide standards by cation-exchange and reversed-phase high-performance liquid chromatography

Column Classification/Characterisation of Strong Cation Exchange Phases for the Liquid Chromatographic Analysis of Small Molecular Weight Bases

“…In contrast to the lack of hydrophobic interaction observed between neutral hydrophobic analytes and the SCX phases, the results confirm that hydrophobic interactions are possible due to the hydrophobic spacers between the silica and sulfonic acid moiety as the protonated base is drawn into the stationary phase. Consequently, low levels of organic modifier are typically required in the mobile phase to diminish any hydrophobic interactions [18][19][20]. The hydrophobic interaction appears to be more pronounced with the hydrophobic bases -diphenhydramine and nortriptyline (logD = 0.6 and 1.66 for, respectively) compared to the polar bases -benzylamine and salbutamol (logD = − 2 and − 2.49 for, respectively).…”

Investigation into reversed-phase chromatography peptide separation systems Part IV: Characterisation of mobile phase selectivity differences

“…There is a wealth of published information regarding the mechanistic effect ion-pairing reagents [1][2][3][4][5][6], pH [7][8][9][10], temperature [6,7,[11][12][13], mobile phase composition [7,8,10] and differing stationary phases [6,7] have on the prediction of peptide retention and selectivity in reversed-phase LC. The groups of Hodges, Hearn, Krokhin and Gilar have devoted extensive research to enhance the current understanding of the retention mechanisms of peptides on RP columns [6,8,9,[14][15][16][17][18][19][20][21][22][23][24][25][26]. Peptide separations are typically performed on C18 columns using a mobile phase pH of between 2 and 7 with or without an ion-pairing reagent which interacts with protonated amino functionalities within the peptide molecule (i.e.…”