Molecular Shape Selectivity through Multiple Carbonyl- Interactions with Noncrystalline Solid Phase for RP-HPLC
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- 作者：M. Mizanur Rahman ; Makoto Takafuji ; Hamid R. Ansarian ; and Hirotaka Ihara
- 刊名：Analytical Chemistry
- 出版年：2005
- 出版时间：October 15, 2005
- 年：2005
- 卷：77
- 期：20
- 页码：6671 - 6681
- 全文大小：239K
- 年卷期：v.77,no.20(October 15, 2005)
- ISSN：1520-6882
文摘
A new approach for the synthesis of double-alkylatedL-glutamide-derived stationary phases to use in RP-HPLCis described. TEM observation of lipid distearylglutamide(DSG) showed the formation of fibrous aggregates inmethanol or in chloroform through intermolecular hydrogen bonding among the amide moieties while dibutylglutamide (DBG) cannot aggregate in aqueous or organicmedia due to its lower order of short alkyl chain. DSGand DBG were covalently bonded to silica via amino-propyl linkages. Lipid membrane analogues (e.g., DSG)attached to the silica surface have been found in noncrystalline and solid states and can form supramolecularassemblies with specific properties based on their highlyordered structures in aqueous and organic media.13C CP/MAS NMR and suspension (in methanol)-state1H NMR, elemental analysis, and DSC measurementswere used to characterize Sil-DSG and were comparedwith the three other octadecyl phases, i.e., monomericC18, polymeric C18, and silica grafted poly(octadecylacrylate) Sil-ODA25. The chromatographic behavior of thenew RP material was investigated using detailed retentionstudies of planar and nonplanar polyaromatic hydrocarbons (PAHs) and nonpolar aromatic positional isomers.Aspects of shape selectivity were also evaluated withStandard Reference Materials 869a, Column SelectivityTest Mixture for Liquid Chromatography. Detailed chromatographic study revealed that Sil-DSG showed extremely enhanced molecular shape selectivity comparedwith the other phases investigated. The higher molecularshape selectivity obtained by Sil-DSG can be explainedby a carbonyl 
(present in lipid-grafted stationary phases)-benzene (present in guest PAHs) interaction mechanism, and these interactions are more effective for orderedcarbonyl groups.
(present in lipid-grafted stationary phases)-benzene (present in guest PAHs) interaction mechanism, and these interactions are more effective for orderedcarbonyl groups.