Polysodium N-Undecanoyl-l-leucylvalinate:  A Versatile Chiral Selector for Micellar Electrokinetic Chromatography

Abstract

Dipeptide micelle polymers are a new class of polymeric surfactants of which the polysodium undecanoyl-L-leucylvalinate (poly-L-SULV) was found to be a broadly applicable chiral selector for micellar electrokinetic chromatography. This negatively charged dipeptide micelle polymer is a high molecular weight compound with large countercurrent mobility, zero critical micelle concentration, low aggregation number, and high solubility in water or water-organic solvents. In an extensive chiral screening program, enantioseparation of 75 racemic compounds was tested with poly-L-SULV as chiral pseudostationary phase in neutral pH and basic pH background electrolytes. A total of 58 out of 75 racemic compounds could be resolved after choosing an appropriate concentration of poly-L-SULV. Although anionic chiral analytes are difficult to resolve using poly-L-SULV, the percent success rate for chiral resolution of cationic (77%) and neutral (85%) racemates was very high. Aspects regarding electrostatic, steric, hydrophobic, and hydrogen-bonding interactions of this dipeptide micelle polymer with various classes of chiral analytes are discussed.

Glycine-based polymeric surfactants with varied polar head group: I. Synthesis, characterization, and application in micellar electrokinetic chromatography

“…In addition to the surfactant head group, effects of hydrocarbon chain length of both conventional surfactants [11][12][13][14] and polymeric surfactants [15][16][17][18][19][20][21] on chemical selectivity have been investigated. While the effects of the polar head group of amino acid-based polymeric surfactants have received considerable attention, these studies have been limited to chiral separations [22][23][24][25][26][27]. In 1997, Shamsi et al [28] employed a poly(sodium N-undecenoyl-L-dipeptide) surfactant with two chiral centers to achieve improved chiral separations in MEKC.…”

Method Development by Use of Capillary Electrophoresis and Applications in Pharmaceutical, Biological and Natural Samples

“…This usually provides higher efficiencies and rapid analysis. They have, over the years, been extensively used in a BGE [74][75][76][77][78][79][80], in a polyelectrolyte multilayer coating [63,74,[81][82][83], and in a CE-MS system [84][85][86].…”

“…As far as the chiral selector is concerned, different polymeric surfactants were examined, such as poly(sodium N-undecanoyl-L-leucinate) (poly-L-SUL), poly(sodium N-undecanoyl-LL-leucyl-leucinate) (poly-LL-SULL), poly(sodium N-undecanoyl-LL-leucyl-valinate) (poly-LL-SULV), poly(sodium N-undecanoyl-L-valinate) (poly-L-SUV), poly(sodium Nundecanoyl-L-valyl-glycinate) (poly-L-SUVG), poly(sodium N-undecanoyl-LL-alanylvalinate) (poly-LL-SUAV), poly(sodium N-undecanoyl-LL-leucyl-alanate) (poly-LL-SULA), and poly(sodium N-undecanoyl-LL-valyl-valinate) (poly-LL-SUVV). The polymeric surfacant poly-LL-SULV, which has shown the best chiral discrimination ability for a number of pharmaceutical compounds [80], was the first to be examined in different concentrations. The concentration of 0.075% w/v was chosen as the optimum, based on analysis time, efficiency and resolution.…”

Recent progress in the use of soluble ionic polymers as pseudostationary phases for electrokinetic chromatography

“…An extensive study of the performance of LL-leucyl-valinate showed that the chiral polymer was able to provide some level of resolution for 58 of 75 cationic, neutral, and anionic racemic compounds [33]. Anionic compounds were more difficult to resolve, presumably due to ionic repulsion.…”