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Polymeric alkenoxy amino acid surfactants: IV. Effects of hydrophobic chain length and degree of polymerization of molecular micelles on chiral separation of β‐blockers
Author(s) -
Rizvi Syed Asad Ali,
Shamsi Shahab A.
Publication year - 2005
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500199
Subject(s) - pulmonary surfactant , monomer , polymerization , chemistry , degree of polymerization , double bond , polymer chemistry , micelle , polymer , chemical engineering , organic chemistry , aqueous solution , biochemistry , engineering
Four alkenoxy leucine‐based surfactants with C 8 –C 11 chains containing a terminal double bond, and one C 11 chain surfactant with a terminal triple bond are synthesized and characterized in monomeric and polymeric forms. These polymeric pseudophases are then utilized to study the influence of chain length and DP for the enantioseparations of seven β‐blockers in MEKC. Variations in chain length and concentration of polymeric surfactants showed significant effects on the chiral resolution ( R s ) and efficiency ( N ). A relatively large elution range combined with the highest polarity and aggregation number ( A ) but the lowest retention time, partial specific volume, and optical rotation generated with C 8 ‐polymeric surfactant results in simultaneous enantioseparation of all seven β‐blockers with higher N and R s . In particular, highly hydrophobic β‐blockers are better resolved with shorter hydrocarbon chain even at higher surfactant concentration, which is unachievable with longer chain surfactant. On the other hand, polymer derived from C 11 ‐triple bond provided smaller A value compared to C 11 ‐double bond surfactant. However, chiral R s of hydrophobic β‐blockers are still achievable with the C 11 ‐triple bond surfactant with enhanced N and shorter analysis time. In addition, effect of polymerization concentration is evaluated by polymerizing all five surfactants at five times their respective CMCs and 100 m M equivalent monomer concentrations. Polymerization of shorter chain (C 8 and C 9 ) double‐bonded surfactants at five times their respective CMCs results in higher A values with better chiral R s and N compared to the same two surfactants polymerized at 100 m M .