Development of Venturi Electrospray Ionization Mass Spectrometry
碩士 === 國立高雄大學 === 應用化學系碩士班 === 101 === A handy ionization method on the basis of Venturi effect was developed. The method was named as Venturi electrospray ionization mass spectrometry (VESI-MS). VESI-MS can self-pumping sample solution into the ion source of Q-TOF mass spectrometry. Sample inlet de...
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| Format: | Others |
| Language: | zh-TW |
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2013
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| Online Access: | http://ndltd.ncl.edu.tw/handle/53150086300932469496 |
| Summary: | 碩士 === 國立高雄大學 === 應用化學系碩士班 === 101 === A handy ionization method on the basis of Venturi effect was developed. The method was named as Venturi electrospray ionization mass spectrometry (VESI-MS). VESI-MS can self-pumping sample solution into the ion source of Q-TOF mass spectrometry. Sample inlet device of VESI-MS can be either single or dual inlets. VESI-MS can perform online study on organic reactions in real-time and investigated effects of experimental conditions on variation of products. Result will assist researchers to understand reaction mechanisms that interested. VESI-MS with dual inlets was applied for modification of matrix in sample solution to enhance analyte ionization efficiency or to perform kinetic method.
Studies showed that nitrogen used as nebulization gas for ESI is the major driving force for self-pumping and formation of Taylor cone has only minor effect. Self-pumping flow rates of glucosamine solution are 19.9 ± 1.9 μL / min and 18.7 ± 1.1 μL / min for turning on or off capillary voltage, respectively. The self-pumping flow rate is affected by solvent used and diameter of tubing for transporting solution. Suitable diameter of transporting tubing is ranged from 75 μm to 250 μm and lengths of transporting tubing should be less than 20 cm and 15 cm for PEEK and capillary tubes, respectively.
VESI-MS was demonstrated to investigate tryptic digestion of cytochrome c in real-time. Result showed that formation KIFVQK is more facile than that of IFVQK. The hydrolysis rate of lysine (K) is affected by its location on cytochrome c. VESI with dual inlets (T-VESI) was applied to improve signal intensity. Intensity of protonated caffeine is enhanced approximately 55 times after online adding acetic acid aqueous solution into sample solution via T-shape connector. Formation of sodiated caffeine cation is also suppressed. Moreover, T-VESI was combined with kinetic method to distinguish acetanilide (AA) and N-methylbenzamide (NMB). AA and NMB are isomeric products that generated from acetophenone via Beckmann rearrangement. T-VESI can be used for post-reactor mixing reference compound acetaminophen (APAP) and AA or NMB standard to perform kinetic method. Collision-Induced dissociation of proton-bound dimers generated showed that the relative intensities of fragments are IAA/IAPAP = 0.15 and INMB/IAPAP = 4.17. These data were applied to solve relative amount of AA and NMB in artificial sample and the result is inconsistent with expectation. The strategy can be used to investigate effect of reaction conditions on isomeric selectivity in the future.
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