New Technology Of Small Mass Spectrometry And Soft Ionization Ionization Source And Its Application

This doctoral dissertation involves studies of analytical chemistry of chemistry discipline and the corresponding analytical instrumentation. Aims of the study are to develop the new pragmatic techniques of mass spectrometry (MS). The dissertation starts a series of useful research work including the ion source technique and sample pretreatment in mass spectrometry based on the present bases. The main contributions are:(1) a miniature Electron Ionization Time-Of-Flight Mass Spectrometer was equipped for realtime gas analysis in industry, which innovatively uses an additional pulse device in TOFMS for the first time to fully remove the harmful ions of helium carrier gas;(2) three kinds of new ion source including a focusing cone-electrospray ionization source were produced, these sources improve ionization methodology in MS;(3) an efficient enrichment of low-concentration proteins in urinary system was established, providing a useful enrichment tool for urinary proteomics and of great potential clinical applications.Nowadays, hyphenation techniques of MS with other analytical methods have achieved breakthrough progress in various areas, which promote the expanded applications. MS development appears two directions. One is the advanced mass spectrometer mainly pursue high performance so as to compact the performances of high-sensitivity, high-precision, high-accuracy, high throughput and high-intelligence, for a wide universality of usage, for example the Biological Mass Spectrometer. The other is to design the special-used instrument for specific users, turning out to be more exclusive by reasonably strengthen or simplification of some parameters. According to the development trends, the dissertation takes the practicability in industry and science as point of penetration. A new type of process mass spectrometer is centrally built for industrial use, while new ion sources and modified sample pretreatment method are also developed for advanced mass spectrometry.The dissertation is composed of5chapters. Brief introduction for each chapter is given as follows:Chapter one summarizes the MS history, the trend and the update innovation requirements of instrumentation. Along with the improvement of performance of MS instrument, the MS applications come to be more and more prevalence. Development of ion source, analyzer and accessory system would directly lead to MS applications in isotope, inorganic, organic and biological field, and also these are various develop trends of MS. High resolution MS and miniature mass spectrometer represent two separate directions for the new generation of mass spectrometer from an overall point of view. The applications of MS instruments are generally divided into two categories, namely, universal tandem mass spectrometer and specialized mass spectrometer. In the mean time, the combination of MS instruments with other type instruments turns to be more common and flexible, making ion source and interface to be hot research topics. This chapter reviews advances of three of the frontier fields:process mass spectrometers; miniature mass spectrometry and field analysis technology; bioMS sample pretreatment protocols and the corresponding ionization methods. Based on the review, the subjects of this study, including design of new ion source, optimization of sample pretreatment method, were presented.Chapter two describes the development and research of a miniature EI-TOFMS, including its integrated design, manufacturing, assembly, signal adjusting, and the matching accessories. Designed for online gas monitoring, the miniature MS instrument is composed of Electron Ionization (EI) source, TOF analyzer and pulse device of removal of helium ion. The main creative points of the mass spectrometer are described as follows:(1) For the first time, we successfully use a high voltage pulse device in TOFMS for helium ions removal, so that not only to achieve lower limit of detection and higher sensitivity, but also to prolong the life of the MicroChannel plate;(2) The modularized design, assembly and maintenance mode are employed in the whole MS instrument, which can ensure the instrumental precision and maintenance convenience;(3) A dual-filament El source is applied to prevent the instrument running from interruption. Vacuum cavity is integrally machined to achieve ultimate vacuum and improved manufacturing precision, which is also good for anti-vibration. A home-made Tablet-type Non Evaporable Getter pump is developed to match with miniature MS, providing effective vacuum for field analysis. Predesign of the miniature EI-TOFMS is completed by SIMION and SolidWorks. The manufacturing process strictly follows quality assurance policies. The resolution of the first instrument is1000FWHM after modulation, the mass range is1-300amu, and the sensitivity achieved PPM level, meaning its whole performance is better than the similar domestic mass spectrometers.Chapter3mainly describes two new types of spray ionization source. For the first one, the interface of the Electrospray Ionization source has been modified and its performances were optimized. Theoretical simulations are conducted based on the conception of the ESI ion plume focusing in a cone style-high voltage electrostatic field just in contrast to the low ion transfer efficiency and instability of traditional ESI. SIMION simulation indicates that the end tip of the ion beam between spray needle and injection port which located in conical dispersion is suppressed and is contracted under the effect of the additional funnel-shaped electric field, and also the ion density is thus increased which can directly increase the sensitivity of ESI-MS. The test results prove that this kind of ion source is stable with low spectral noise and greatly improves signal-to-noise ratio due to the greatly reduced external interference. Another ion source is a brand new low-pressure ion source which can be applied as supplement of existing ionization methods or used in the in-situ monitoring. Add a drop of sample solution onto the atomizer plate, and the solution surface can be atomized by the ultrasonic cavitation, while the capillary wave will aggravate the friction between the micro droplets and finally produce sample ions. Ultrasonic spray ionization (USI) is a novel and convenient ionization method, and the results of ESI-MS experiments have shown its good performance and unique ionization mode.In chapter4some new ideas on Atmosphere Pressure Matrix-Assisted Laser Desorption Ionization (AP-MALDI) is proposed and studied. AP-MALDI is similar to MALDI, but it is a more soft ion source which only needs very low power for ion generation and can combine with various mass spectrometers as a relatively independent ion source. Its main disadvantage is the losses of ions at the vacuum interface that significantly reduced MS sensitivity. An attempt study of whether the combination of UV light source with inorganic compounds, or the combination of Visible light source with organic matrix would furthermore improve the ionization performance of AP-MALDI, was carried out in the dissertation. Firstly, we designed a movable optical platform which can assemble optical equipments; then, we built up a complete laser system and each the component can be adjusted at ease; The heated tube between the ion source and mass spectrometer is designed adjustable, to match the different mass spectrometers. The experimental platform can be flexibly suitable for use in various MS instruments just by only changing the laser device and matrix.Chapter5describes the use of nano-particle material to enrich urine proteins in the pretreatment process, and that is a noble innovation in the urinary proteomics field. Traditional urinary proteomics normally utilize techniques of2DE-MS, LC-MS/MS、 PC-MS and CE-MS while their pretreatment methods are all complicated with low efficiency. The experiment used silica nano-particle material for urinary protein enrichment and successfully identified about2000proteins via ID SDS/PAGE-LC-MS/MS technical route, which was a great improvement to the existing urinary proteomics methods. Further work develops bioinformatics analysis on the identified urinary proteins and the analysis results prove the advances of the enrichment method. The physicochemical properties for all these protiens in urine are stable and without discrimination of hydrophilic-hydrophobic property as well as iso-electric point; large amount of valuable extracellular proteins are enriched and identified, especially including quite a lot of invaluable exosome proteins which are insoluble and hard to extract. The enrichment experiment results also suggest that the high expressed proteins are suppressed while the low abundance proteins are enhanced, and proteins are immobilized in some degree during the enrichment course. The samples used in, the whole experiment were obtained from patients with Transitional Cell Carcinoma of the bladder. The data process results indicate that this enrichment approach can be widely used for searching biomarkers in the early diagnosis.In summary, the dissertation provides new techniques and methods to improve the practicability of mass spectrometry, and they are described as follows:(1) Maintaining the resolution of1000, a miniaturized the Electron Ionization Time-Of-Flight Mass Spectrometer is made, and a helium ion removal pulse device is invented, performances of the instruments aims at long continuous working time, good stability, high automation and strong practicality;(2) As new spray ionization sources, devices of focusing cone-electrospray ionization and ultrasonic spray ionization are developed, and the former raises the sensitivity and stability than the existing ESI, while the latter is a novel soft ionization method without need of high voltage or high pressure;(3) On the basis of research of Atmosphere Pressure Matrix-assisted laser desorption ionization, an open optical platform which is convenient for ionization research and integral transportation have been built up.(4) Nano-particles silica is creatively used to enrich urinary proteins, and it provides more high efficient methods for protein enrichment in urinary proteomics studies and a simple and practical approach to the early stage of diagnosis.