| Ultra performance liquid chromatography and mass spectrometry (UPLC-MS) has grown to become a mature and routinely used technique in analytical chemistry since 2004. UPLC-MS is an online coupling system of UPLC, a separation technique that can be applied to the extremely complex mixtures, and MS, the most sensitive method of molecular analysis that has the potential to yield information of the molecular weight as well as the structure of the analyte. It provides a low limit of detection and as an identifier for structural information.UPLC-MS has become a powerful and important technique and method in analysis of medicines in the complex mixtures.In this thesis, we comparative study on the separation of cephalosporins by the new rapid liquid chromatography column. We successfully developed electrospray ionization tandem mass spectrometry coupled with ultra performance liquid chromatography to screen for agrimols with potent activity against Staphylococcus aureus from Rhinacanthus nasutus ( L.) Kurz and C21 steroidal glycosides with immunological activities from Stephanotis mucronata. In order to differentiate isomers in extracts, we also investigated C21 steroidal glycosides by ultra performance liquid chromatography tandem mass spectrometry using ferrous chloride as a postcolumn reagent based on previous investigations of offline regioisomer characterization of C21 steroidal glycosides. In addition, the principle of LC-MS technique and its extensive application in pharmaceutical analysis were reviewed in detail.First, the characteristics and performance of five different C18-bonded silica columns including Halo-C18 column, Zorbax Eclipse XDB-C18 column, Zorbax SB-C18 column, ACQUIT UPLC BEH-C18 column and the coupled column of Halo-C18 column and Zorbax SB-C18 column to separate the cephalosporins in the gradient elution mode were investigated. The results indicate that the Halo-C18 column provides a higher performance than that of Zorbax Eclipse XDB-C18 column and Zorbax SB-C18 column. Furthermore, the efficiency and resolution of the coupled column were nearly same as that of UPLC column. However, the back pressure of the coupled column was 50 % lower than that of the UPLC column. It is obvious that the coupled column can offer rapid, high performance separation of compounds instead of UPLC column with a conventional chromatography instrument.Second, Ultra performance liquid chromatography tandem mass spectrometry was developed for screening of grimols which were homologous series in the roots of R.nasutus by means of online high–resolution HPLC/TOF-MS. Fragmentation pathways and major fragment ions were determined. As a result, nineteen phloroglucinol derivatives including five groups of isomeric compounds are rapidly analyzed and identified, and twelve of these are observed here for the first time in this plant.At last, The fragmentation patterns of compound induced by metal ion can be significantly altered, allowing new opportunities for structural determination. We have systemically investigated fragmentation patterns of C21 steroidal glycosides induced using the ferrous chloride as a postcolumn reagent, the non-reducing end glycoside stereoisomers were differentiated. |
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