Ambient ionization mass spectrometry, which has witnessed a flurry of recent developments, is a set of useful techniques for the analysis of samples under open-air conditions. It allows direct, rapid, real-time, high-throughput analysis with little or no sample pretreatment for the chemicals in solids or liquids. In this study, thermal desorption electrospray ionization mass spectrometry ( TD-ESI/MS ) involving direct insertion probe ( DIP ), thermal desorption ( TD ) and electrospray ionization ( ESI ) was used for the rapid screening of various types of samples. The source mainly consists of the sampling probe device, thermal desorption heating device, electrospray ionization device, ion source and temperature controller. A novel strategy involved in TD-ESI/MS processes where sampling, desorption, and ionization are separated as three independent events. The sampling probe is first used for the sampling of analytes and then inserted into a heat unit for thermal desorption. The desorbed analytes are finally carried into a reaction region with a stream of nitrogen gas, where charged methanol droplets were generated continuously by electrospray for post-ionization. Total analysis time is less than 10 seconds. Traditionally, three standard methods are used for the analysis for pesticide residues, biochemical, immunoassay and instrument. And, the instrument analysis is the most widely used because it provides lots of advantages in particularly accurate quantitative approach. However, its complicated steps take a long period of time for preparation. Here, we used TD-ESI/MS to rapidly screen the pesticide residues on the surface of fruits and vegetables. The MS/MS analysis was also performed to confirm those detected compounds. The experimental results of the standard deviation for reproducibility is 13.2% (n = 10), and the detection limit is approximately 10 ppb. Furthermore, several fruits and vegetables purchased from local market were used as test samples and pesticide residues on the surface of samples can be successfully detected via TD-ESI/MS. In addition, the TD-ESI/MS technique was also applied to the analysis of illegal additives or phthalates in food. In this study, the TD-ESI/MS technique emerges lots of advantages such as direct, rapid, real-time analysis of sample surface and sample pretreatment is not necessary, and shows highly potential for rapid screening of chemicals in food safety.

Ambient mass spectrometry is one of the mainstream techniques in modem mass spectrometry development. The developing purpose of ambient mass spectrometry is improving the analysis efficiency and simplifying operation process. So that, there are many techniques about ambient mass spectrometry had been published and commercialized. And direct electrospray probe mass spectrometry (DEP/MS) is one of ambient mass spectrometry techniques which is emphasized its rapid analysis and high sampling space resolution. In this research we improved the DEP system for more suitable in rapid analysis. We rule of the use of Syringe pump and its tube. Replace it by using solution tank so that we can save the time cost by disassemble syringe pump and tube when sampling. We also change the electric field by different high voltage applied mode for safety concern. In this study DEP/MS were used in plants analysis applications: capsaicin in peppers, systematic pesticide absorption in tomato and toxic compounds distribution in potato surface.

Stirring tanks are very important equipments used for mixing, separating, chemical reaction, etc. A typical stirring tank is a cylindrical vessel with an agitator driving the fluid and generating turbulence to promote mixing. Flotation cells are widely used stirring tanks in phase separation where multiphase flow is involved. Flotation refers to the process in which air bubbles selectively pick up hydrophobic particles and separate them from hydrophilic solids. This technology is used throughout the mining industry as well as the chemical and petroleum industries. In this research, efforts were made to investigate the multi-phase flow hydrodynamic problems of some flotation cells at different geometrical scales. Pitot-static and five-hope probes were employed to lab- pilot- and commercial-scale tanks for velocity measurements. It was found that the tanks with different scales have similar flow patterns over a range of Reynolds numbers. Based on the velocity measurement results, flotation tanks' performance was evaluated by checking the active volume in the bulk. A fast-response five-hole probe was designed and fabricated to study the turbulence characteristics in flotation cells under single- and multi-phase flow conditions. The jet stream in the rotor-stator domain has much higher turbulence intensity compared with other locations. The turbulent dissipation rate (TDR) in the rotor-stator domain is around 20 times higher than that near tank's wall. The TDR could be used to calculate the bubble and particle slip velocities. An isokinetic sampling probe system was developed to obtain true samples inthe multi-phase flow and then measure the local void fraction. It was found that the air bubbles are carried out by the stream and dispersed to the whole bulk. However, some of the bubbles accumulate in the inactive regions, where higher void fractions were detected. The isokinetic sampling probe was then extended to be an isokinetic borescope system, which was used to detect the bubble-particle aggregates in the tank. Aggregates were found in the high-turbulence level zones. The isokinetic sampling probe and the isokinetic borescope provide new methods for flotation tank tests. An experiment was also set up to study the dynamics of bubble particle impact. Four different modes were found for the collision. The criterion is that if the fluid drainage time is less than the residence time, the attachment will occur, otherwise, the particle will bounce back. / Ph. D.

The direct sampling of analytes from surfaces under atmospheric conditions followed by mass spectrometric analysis is an ever expanding area of scientific research. Atmospheric pressure surface sampling and ionization techniques for mass spectrometry (MS) offer the ability to interrogate samples that could not be studied under vacuum conditions required of more traditional MS surface analysis techniques. The geometry and nature of materials or surfaces that can be analyzed has been greatly expanded as a result. This dissertation characterizes and shows applications of liquid microjunction surface sampling probe (LMJ-SSP) electrospray ionization systems. The presented work compares traditional analytical work flows with novel analytical workflows utilizing LMJ-SSP-MS technology. The increase of throughput and/or chemical information without the sacrifice of analytical figures of merit is shown and discussed. The readout of analytical surfaces; surfaces where analyte has ended up on a surface in a traditional work flow and not just placed there, constitutes the focus of what is presented in the preceding work. Finally the prospects for spatial liquid chromatography-mass spectrometry (LC-MS) as a powerful analytical technology „in wait‟ is discussed and supported by the presented data.

Particle ingestion is a prevalent issue for jet engines. During operation, sand and ash particles enter the engine and can cause serious problems, including erosion and buildup of Calcia-Magnesia-Alumina-Silicate (CMAS) deposits. Analyzing the particle mass concentration of the airflow can help better understand this issue. This can best be accomplished by sampling particles with a sampling probe at various locations within an engine. The present study is a continuation of a previous study that developed and evaluated a novel sampling probe. The present study seeks to modify the probe to optimize its sampling capability, to evaluate the aerodynamics of the modified probe through Particle Imaging Velocimetry (PIV), to gain insight on its ability to sample smaller particles, to characterize the movement of larger particles as they are sampled using Particle Tracking Velocimetry (PTV), and to develop a method to physically measure particle mass concentration. To accomplish this, a free jet rig was used to create a particle-laden flow, and the probe was placed at the jet exit to sample particles. A laser and camera system were used to capture images of the probe for PIV and PTV. A particle collection apparatus was designed to collect and weigh particles captured by the probe to measure mass concentration. The PIV results indicate that the probe exhibits sub-isokinetic sampling behavior. However, the PTV results show that large particles are not affected by non-isokinetic conditions. The mass concentration measured by the probe decreases when the flow Mach number increases due to the higher flow velocity causing particles to be spaced further apart. The mass concentration measured by the probe decreases when the probe yaw angle increases due to lower projected probe inlet area. / Master of Science / Sand and ash particles are harmful to jet engines. Particle ingestion can greatly affect the useful life of the engine. Particles erode the machinery within the engine, and they also melt to form mineral deposits, all of which degrades performance. One method that is being developed to better understand this problem is to sample particles at various locations in the engine using a sampling probe. The concept of a sampling probe is simple: particles are captured by the probe inside the engine, and the particles are collected outside the engine for analysis. This would give insight on particle behavior in the engine. The present study is a continuation of a previous study that developed and evaluated a novel sampling probe. The present study seeks to modify the probe to optimize its sampling capability, to use advanced imaging techniques to characterize the movement of air and particles entering the probe, and to safely collect and weigh particles captured by the probe. A compressed air jet was used to accelerate particles and create a particle-laden environment akin to the inside of an engine. The probe was placed at the exit of the jet to sample particles. A laser and camera system were used to capture images of the probe during the particle-sampling process. A particle collection apparatus was designed to safely collect and store particles captured by the probe for weighing. The image and weight data were then used to make conclusions about the probe's sampling capability.

Particle ingestion remains an important concern for turbine engines, specifically those in aircraft. Sand and related particles tend to become suspended in air, posing an omnipresent health threat to engine components. This issue is most prevalent during operation in sandy environments at low altitudes. Takeoffs and landings can blow a significant quantity of particulates into the air; these particulates may then be ingested by the engine. Helicopters and other Vertical Takeoff and Landing (VTOL) aircraft are at high risk of engine damage in these conditions. Compressor blades are especially vulnerable, as they may encounter the largest of particles. Robust and thorough experimental and computational studies have been conducted to understand the relationships between particle type, shape, and size and their effects on compressor and turbine blade wear. However, there is a lack of literature that focuses on sampling particles directly from the flow inside an engine. Instead, experimental studies that estimate the trajectories and behavior of particles are based upon the resulting erosion of blades and the expected aerodynamics and physics of the region. It is important to close this gap to fully understand the role of particulates in eroding engine components. This study investigated the performance of a particle-sampling probe designed to collect particles after the first compressor stage of a Rolls-Royce Allison Model 250 turboshaft engine. The engine was not used in this investigation; rather, a rig that creates a particle-laden jet was developed in order to determine probe sampling sensitivity with respect to varying angles of attack and flow Mach number. Particle image velocimetry (PIV) was utilized to understand the aerodynamic effects of the probe on smaller particles. / Master of Science / Aircraft jet engines are constantly exposed to particles suspended in the atmosphere. Most jet engines contain several stages of spinning blades. The first series of stages near the front of the engine comprise the compressor, while the series towards the end of the engine comprise the turbine. Engines depend on compressor blades to add energy to the flow via compression and turbine blades to extract energy from the flow after combustion. Thus, they are critical for the successful operation of the engine. The constant impact of airborne particulates against these blades causes erosion, which alters blade geometry and thereby engine performance. Depending on the turbine inlet temperature, particles may melt and clog the cooling passages in turbine blades, causing serious damage as the blades reach temperatures above their intended operating regime. These damages inhibit the ability of the engine to operate properly and pose a serious safety risk if left unchecked. In literature, experimental engine erosion correlations and numerical models of particle trajectories through the engine have been developed; however, none of these studies collected particles directly from the compressor region of the engine. In this study, a probe was developed and evaluated for the purpose of sampling particulates between the first and second compressor stages of a Rolls-Royce Allison Model 250 turboshaft engine. The probe's efficacy and aerodynamic properties were analyzed such that the probe will provide processable data when inserted into the engine. The methods to obtain this data include particle-sampling and particle image velocimetry (PIV).