The Development Of An Atmospheric Pressure Plasmaspray Ionization And With The Combination Of Time Of Flight Mass Spectrometer

Mass Spectrometry as an important analytical technique, is widely used in the fields of chemistry, physics, biology, medicine and so on. As the core component of the mass spectrometer, ionization technique has been developed widely in the recent years. With the introduction of a new group ambient desorption/ionization sources known collectively as direct ionization techniques, Mass spectrometry has undergone a contemporary revolution. To date, more than 50 ionization techniques have been developed. In this study, an atmospheric pressure plasmaspray ionization(PSI) technique with the independent intellectual property rights was developed. It is composed of a low temperature plasma jet device and a sample spray part, and the homemade time-of-flight mass spectrometer application of this technique was done. Compared with ESI source, the technology has the characteristics of high sensitivity and good linearity. The main detail jobs which did by the actor were as follows: 1) Participated in the completion of installation of the atmospheric flight mass spectrometer, and completed the commissioning of the instrument independently. To predict the performance of the instrument: 100 ppb Reserpine, the signal strength more than 800, the resolution is better than 4300. 2) Independently completed the design of the low temperature plasma assisted ionization source. The new atmospheric pressure plasmaspray ionization comprises a dielectric barrier discharge plasma jet device and a sample spray part. In this study, these factors which content the discharge gas species、the relative position of the electrodes、the flow of the discharge gas、the voltage and frequency of the discharge power have been studied。The optimal conditions of these factors are as follows: the He discharge gas flow rate was 450ml/min、 the frequency of the discharge power was 6.25KHz、the voltage of the discharge power was 3000 V. 3) The comparison of the PSI and the ESI was completed. Under the same conditions of the mass spectrometer parameters, when the PSI was combined with the time-of-flight mass spectrometer the linearity of the instrument was good than the ESI. The mass spectra for both PSI and ESI sources of caffeine, reserpine, PPG, PEG and phospholipids response the results that PSI shows the characteristic of ESI to produce only the protonated ion [M+H]+,and with the signal intensity being comparable with or even higher than that of ESI. The main job in the future is to explore the ionization mechanism and develop the application 4) To explore the ionization mechanism. In the helium plasma jet, there exists many kinds of particles, like He+, He*, product ions of He+, He* reacting with air molecules and also electrons and photos with relative high energy. when the particles strike the surface of the stainless steel tube, an ungrounded conductor, the free electrons which move randomly in the conductor will escape through photoelectric effect, charge transfer, etc. Duo to the end of capillary is much sharper, and most of the charges in the sample solution will gather to the end of capillary. When the solution flow passes through the end of capillary, the charge liquid drops will be formed with the assist of the spraying gas, and then they will go the same road as the ESI does. About the specific mechanism with studied in the future work.