title: Enantiomer resolution of D- and L-alpha-amino acid derivatives by supercritical fluid chromatography on novel chiral diamide phases with carbon dioxide.
abstract: The rapid resolution of racemic N-4-nitrobenzoylamino acid isopropyl esters was accomplished without the loss of enantioselectivity by supercritical fluid chromatography (SFC) on novel chiral valine-diamide phases with carbon dioxide and a polar methanol modifier. In each stationary phase, a chiral moiety was anchored to the silica gel surface by a long decamethylene spacer. The enantioselectivity in SFC was comparable to that in liquid chromatography using 2-propanol-n-hexane. The time required for analysis was less than 5 min, and the range of enantiomer resolution (Rs) was 10.8-1.25. On using 2-propanol in place of methanol the separation was improved, but was accompanied by a decrease in column efficiency. The end-capping effect of the remaining surface silanols on enantiomer resolution is discussed.
authors.affiliation: Tokyo College of Pharmacy, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Dobashi
authors.forename: Y
authors.initials: Y
authors.lastname: Dobashi
authors.forename: T
authors.initials: T
authors.lastname: Ono
authors.forename: S
authors.initials: S
authors.lastname: Hara
authors.forename: M
authors.initials: M
authors.lastname: Saito
authors.forename: S
authors.initials: S
authors.lastname: Higashidate
authors.forename: Y
authors.initials: Y
authors.lastname: Yamauchi
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000378:metabolism; D002845:Chromatography / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D009579:Nitrobenzoates / Q000032:analysis*; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D009579:Nitrobenzoates