Development And Applications Of Several Ambient Mass Spectrometry Technology

Mass spectrometry has become increasingly interested in analytical science due to its high selectivity, sensitivity and throughput. Compared with traditial mass spectrometry, ambient mass spectrometry is featured by direct ionization of trace analytes in complex matrix samples with minimal/no sample preparation and separation. Ambient mass spectrometry has greatly increased the efficiency of mass spectrometry technique. In recent years, ambient mass spectrometry enables rapid analysis of analytes in-situ, real-time, on-line, non-destructive and low sample consumption, has become an important trend in the development of mass spectrometry techniques. The principle and application of several new ambient mass spectrometry methods in the environmental analysis, chemical industry, food safety, etc. have been mainly studied in this thesis.The main contents of this thesis are as follows:1. The EESI-MS analysis of gaseous radioactive iodine-129. For actual air samples, gaseous 129I2 were completely converted into triiodide ion complexes(i.e. 129+127*2I3-), and the quantification of iodine-129 was achieved by quantitative measuring the characteristic fragment(i.e., 129I-) of the triiodide ion complexes, which were subjected to extractive electrospray ionization tandem mass spectrometry(EESI-MS/MS). The limit of detection(LOD) was 4.5 ppt, a relative standard deviation(RSD) was 4.0–13.1%(n=5), and the spiking recovery of the method was found to be 82.6–110.5%. The results demonstrated that EESI-MS can be employed for the quantitative analysis of inorganic radioactive compounds, providing potential applications in many fields including nuclear leakage, nuclear explosions and related scenarios.2. The analysis of ionic liquids(ILs) by EESI-MS. With only minor alterations to EESI experimental setup, the analysis of various room temperature ionic liquids(RTILs) could be performed without dilution, which allowed direct observation of IL aggregates in the gas phase at the speed of > 2 samples per min. Compared to ESI-MS, EESI-MS allows higher rapidity and throughput of analysis with higher sensitivity and minimal matrix effects. Particularly, a softer EESI source can be used as a direct measure to quantify the energy of the cation-anion interaction. Our result for eight different 1-butyl-3-methylimidazolium(Bmim) ILs suggests that Bmim signal intensity is inversely correlated with the hydrogen bonding strength between the anion and cation. The all experimental data demonstrated that the potential of EESI-MS to interrogate large IL assays necessary in both fundamental physical chemistry studies and industrial applications.3. The direct oil analysis by ND-DBDI-MD. Neutral desorption sampling in conjunction with dielectric barrier discharge ionization mass spectrometry(ND-DBDI-MS) has been established for fast and accurate identification of various hogwash oil and edible oil samples. The volatile and nonvolatile fatty acids, representative for oil quality, in oil samples were analyzed directly. Principal component analysis(PCA) and cluster analysis(CA) were applied to probe the differentiation and reproducibility of the analytical method. The experimental results show that ND-DBDI-MS is an important tool for rapid analysis of highly complex viscous samples such as oil samples, providing potential applications in food safety analysis.4. Sensitive ionization of non-volatile analytes by DESI-MS. A sensitive DESI method using dilute solutions of proteins as the ESI spray liquids was developed for the detection of trace chemicals on virtually any solid surface. Compared with the traditional mass spectrometry DESI, protein solutions significantly increased the signal levels of non-volatile compounds, and the LODs of this novel DESI-MS approach for detecting representative compounds were reduced to about half of those obtained by the traditional DESI-MS method using the methanol/water/HAc mixture as the ESI spraying solvent. The proposed DESI method is a universal strategy for rapid and sensitive detection of trace amounts of strongly-bound and/or nonvolatile analytes, including explosives, peptides, and proteins. The results indicate that the sensitivity of DESI can be further improved by selecting larger protein and appropriate solid surfaces.