Development Of Ambient Metastable Desorption Ionization(AMDI) And Study On Its Application

Ion mobility spectrometry (IMS) is an important tool in modern scientific research on molecular properties. As a prerequisite part in the IMS, ion source determines the selectivity and sensitivity of target ions. The development of ion source can be divided into three stages such as vacuum ionization, under atmospheric pressure and atmospheric pressure ionization. Atmospheric pressure ion sources have characteristics as follows:analysis in real time, desorption by itself, soft ionization, simple and portable structure, etc.This paper provides a new atmospheric metastable desorption ion source (AMDI), and investigates in the development and application of this technology. Combined with high field asymmetric waveform ion mobility spectrometry (FAIMS), this thesis investigates the ionization efficiency affected by several parameters. Specific in details include the following three parts of contents.1 A development of a new type of atmospheric FAIMS ion source for atmospheric metastable desorption ion source (AMDI) technology. AMDI provides a clean, stable, high energy (19.8eV) of helium metastable atoms with which the He (23S) is directly or indirectly transfer energy to the target compounds. We explore the voltage, power, frequency, flow rate, desorption temperature and other key parameters affecting the AMDI ionization efficiency from physical properties, and obtain a rich conclusion of the combining with FAIMS.2 For the volatile organic compounds, we detect the trace water ammonia solution with AMDI by simulating the 2014 Wuhan Ammonia Leak. The measurement in the experiment is at least one order lower than the national standard of ammonia content in water samples. The high sensitivity of AMDI shows that this ion source with FAIMS completes the rapid real-time analysis of repeated measurements in just few minutes. Examples are given in the difference of xylene isomer, the different illustrates the isomers in FAIMS spectra, in which is able to carry on the separation and identification of isomers.3 Using high field asymmetric ion with atmospheric metastable desorption ion source mobility spectrum AMDI-FAIMS, we build a kind of adjustable closed under atmospheric pressure helium atmosphere temperature sample ionization device, the flow rate of carrier gas 6.2L/min, temperature 692K, AMDI power 1.2W discharge are carried out under the condition of quantitative detection of trace selenium. The experimentally measured 20 μg selenium sample with a signal peak of 5pA. The results show that, to detect selenium with AMDI-FAIMS on low melting point samples and the related conclusion is worthy of further researches and development of ion mobility spectrometry in Inorganic Elements Detection potential. In addition, the L-Glutamic acid, lysine,β-alanine and 1,3-resorcinol were detected, and the results demonstrate the well-development of AMDI in the detecting of solid sample.