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Chiral Analysis Using Capillary Electrophoresis Coupled to Mass Spectrometry: Development of Novel Modes and Applications Using Molecular Micelles and Surfactant-Bound Monolithic ColumnsHe, Jun 13 December 2011 (has links)
Micellar electrokinetic chromatography (MEKC) and capillary electrochromatography (CEC) are two of the major capillary electrophoresis (CE) modes that have been interfaced to mass spectrometry (MS) for sensitive and selective analysis of chiral compounds. This research combines these two modes and expands their applications in chiral CE analysis. Chapter 1 is a review of amino acid based molecular micelles used in MEKC-MS for enantioselective analysis over the past five years. In this chapter, a typical MEKC-MS experiment setup as well as detailed standard operating procedure in synthesis of molecular micelles and running a typical MEKC-MS experiment using the molecular micelles is discussed. Chapter 2 described a multivariate MEKC-MS optimization for the simultaneous analysis of two negatively charged model chiral compounds in negative ion mode with molecular micelles. In this chapter, a central composite design (CCD) is used to first construct a series of experiments to optimize all the important MEKC-MS parameters. Next, response surface methodology (RSM) was used to analyze the interactions between the factors, picking up the best separation and detection conditions, predicting the result of the chiral separation/MS detection, and finally running the actual experiment and comparing the chromatographic results with the predicted parameters. Chapter 3 demonstrates a similar multivariate MEKC-MS optimization for analysis of a positively charged model chiral compound in a positive ion mode. The same CCD and RSM methods were used to optimize the separations and MS sensitivity. Chapter 4 describes a chiral analysis of four neutral benzoin derivatives (hydrobenzoin, benzoin, benzoin methyl ether, and benzoin ethyl ether) using MEKC coupled to atmospheric pressure photo-ionization mass spectrometry (APPI-MS). The same multivariate experimental design strategy was used to optimize the MEKC as well as APPI-MS parameters. Simultaneous chiral separation of all four benzoin derivatives was achieved with high detection sensitivity compared to UV-detection. Chapter 5 introduces a novel one-pot synthesis scheme for an acryloyl-terminated, carbamate-linked surfactant-bound monolith with leucine head group and different chain lengths. The method promises to open up the discovery of new amino acid based polymeric monoliths for chiral separations and enhanced chemoselectivity for simultaneous chiral separations and enhanced detection in CEC and CEC-MS. In Chapter 6, five amide-linked surfactant-bound monoliths with different chain lengths and head groups (leucine, valine, and phenylalanine) were synthesized and characterized. Enantioseparation of several test compounds was achieved by CEC using the monolithic columns. One of the chiral surfactant, sodium 11-acrylamidoundecanoyl-L-leucinate (SAAUL), was polymerized in aqueous solution under 60Co radiation to form molecular micelle poly-SAAUL. MEKC experiments were carried out with the poly-SAAUL molecular micelle to separate ten cationic chiral compounds. The result was compared with the CEC separation using the AAUL monolithic column. This study is the first comparison of chiral CEC and MEKC with the same surfactant monomer, which has the capability of forming both chiral stationary phase for CEC and chiral pseudophase for MEKC.
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Chiral capillary electrophoresis-mass spectrometry: developments and applications of novel glucopyranosdie molecular micellesliu, yijin 09 May 2016 (has links)
Micellar electrokinetic chromatography (MEKC), one of the major capillary electrophoresis (CE) modes, has been interfaced to mass spectrometry (MS) to provide high sensitivity and selectivity for analysis of chiral compounds. The research in this dissertation presents the development of novel polymeric glucopyranoside based molecular micelles (MoMs) (aka. polymeric surfactants) and their application in chiral MEKC-MS.
Chapter 1 is a review of chiral CE-MS - in the period 2010-2015. In this chapter, the fundamental of chiral CE and CE-MS is illustrated and the recent developments of chiral selectors and their applications in chiral EKC-MS, CEC-MS and MEKC-MS are discussed in details.
Chapter 2 introduces the development of a novel polymeric α-D-glucopyranoside based surfactants, n-alkyl-α-D-glucopyranoside 4,6-hydrogen phosphate, sodium salt. In this chapter, polymeric α-D-glucopyranoside-based surfactants with different chain length and head groups have been successfully synthesized, characterized and applied as compatible chiral selector in MEKC-ESI-MS/MS. or the enantioseparation of ephedrines and β-blockers.
Chapter 3 continues to describe the employment of polymeric glucopyranoside based surfactants as chiral selector in MEKC-MS/MS. The polymeric β-D-glucopyranoside based surfactants, containing charged head groups such as n-alkyl β-D-glucopyranoside 4,6-hydrogen phosphate, sodium salt and n-alkyl β-D-glucopyranoside 6-hydrogen sulfate, monosodium salt were able to enantioseparate 21 cationic drugs and 8 binaphthyl atropisomers (BAIs) in MEKC-MS/MS, which promises to open up the possibility of turning an analytical technique into high throughput screening of chiral compounds. Physicochemical properties and enantioseparation capability of polymeric β-D-glucopyranoside based surfactants with different head groups and chain lengths were compared. Moreover, the comparison of polymeric α- and β-D-glucopyranoside 4,6-hydrogen phosphate, sodium salt were further explored with regard to enantioseparations of ephedrine alkaloids and b-blockers. The concept of multiplex chiral MEKC-MS for high throughput quantitation is demonstrated for the first time in scientific literature.
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