A new era of high-throughput mass spectrometry emerged with the nearly simultaneous introduction of two ambient ionization techniques: desorption electrospray ionization (DESI) and direct analysis in real time (DART). The ability to integrate near instantaneous sample analysis with the specificity of mass spectrometry opened up a broad range of applications. While some of these involve the direct analysis of bulk materials, many others require the collection and deposition of samples onto suitable substrates. This dissertation details the development of a new mode of operation for DESI. Instead of depositing a sample onto a continuous surface, the sample is either collected by or deposited onto a mesh substrate. Analytes either adsorb to the mesh strands or become suspended within the confines of the mesh in macroscale droplets. The samples are then analyzed by scrolling the mesh orthogonally into the path of an electrospray plume positioned coaxial to the inlet capillary of the mass spectrometer, thereby resulting in the transmission of the ionizing plume directly through the material. The transmission mode results in desorption and ionization typical of DESI, but with the added benefits of a simpler experimental geometry and the convenient analysis of both dry (i.e., following evaporation of the deposition solvent) and wet (i.e., solvated) samples. The simplification of the experimental arrangement increases method robustness and reproducibility, while the inclusion of a mesh substrate introduces new possibilities for sample collection and introduction, due to the intricate chemistry between the mesh material, analytes, and deposition/electrospray solvent system. However, the most important benefit lies in the development of surface-enhanced TM-DESI, whereby mesh substrates are derivatized to specifically capture and concentrate targeted analytes directly from solution. Following removal of matrix interferences by sample rinsing and subsequent cleavage of a photolabile linker, the mesh is analyzed directly by TM-DESI-MS. The technique has the potential to overcome interferences that have typically required chromatographic separations using LC-MS or have been insurmountable using ambient ionization methods. The impact of the surface-enhanced method could be tremendous as it may ultimately unite the competing metrics of analytical speed and specificity for ambient ionization mass spectrometry. / text

The introduction of ionization under ambient conditions has greatly simplified mass spectrometric analysis. Over past decade, ambient ionization mass spectrometry (MS) methods have revolutionized the way complex samples are analyzed under environmental conditions without requiring, in most cases, any sample pretreatment. Ambient ionization MS gained popularity among other analytical techniques due to its simplicity and its suitability for analysis of small and large molecules. However, ambient ionization methods can suffer from low accuracy and sensitivity due to matrix effects and interferences within complex samples, as well as from poor ionization efficiency. Matrix effects in ambient ionization are usually caused by ion suppression and may depend on different factors, e.g. matrix-to-analyte concentration ratios, proton affinities of analyte and matrix species. To overcome these challenges, in this thesis we present a new approach where a probe is used both as a direct sampling device and as an efficient ambient ionization source. This approach leverages high surface area gold electrodes, fabricated through low-cost bench-top fabrication methods and functionalized using self-assembled alkyl thiol monolayers, as functional conductive sampling probes (FCSPs) for the extraction and concentration of analytes from a sample solution. FCSPs loaded with the targeted analytes were then used to demonstrate a new and highly efficient ionization approach, called Primary Ion Mass Spectrometry Source (PIMSS). In this approach, following capture, the bound analytes are directly desorbed into the mass spectrometer, where ionization is achieved solely through the extraction voltage applied to the probe. 3D-printing was used to design an interface to couple FCSPs to the mass spectrometer. In this work, we discuss a detailed method development and optimization stage and present capabilities of the proposed assay. / Thesis / Master of Science (MSc)

<p>  </p> <p>Miniature mass spectrometers are in a phase of rapid development due to their potential in offering simple yet powerful solutions for a wide variety of unmet biomedical needs. In particular, the combination of ambient ionization methods with miniature mass spectrometers offers an attractive solution for improving patient outcomes and reducing the healthcare burden on patients as well as clinicians opposed to current methods for disease prognosis and diagnosis. </p> <p>There has been a rapid expansion in the commercial offerings of miniature mass spectrometers from commercial vendors, both large and small, including Purspec, Bayspec, MassTech, Waters, and Advion. Despite the large number of instruments that have been made available and the success of many of these systems with analysis of a broad range of biological matrices, much work remains to perform bioanalysis of complex molecules with concentrations that often lie in the ng/mL-µg/mL range. Miniaturization of mass spectrometers is accompanied by design simplifications in comparison to benchtop instruments, so that sacrifices are often made in terms of performance. The figure of merit that is compromised, of course, depends on the design of the instrument itself. Thus, in addition to a good understanding of the operation of the mass spectrometer, it is crucial that the ionization method for the analyte be chosen judiciously, and that the method is suitably optimized to be able to perform the measurements to obtain high quality data for trace analysis. </p> <p>The custom built Mini-12 miniature MS systems at Purdue University is one such miniature mass spectrometer that can be used for making on-site measurements. In this work, I have described my efforts to perform trace analysis of a range of molecules (tenofovir diphosphate, cabotegravir, rilpivirine, and phosphatidylethanol) relevant to HIV treatment and prevention with the Mini-12 system. Based on the most favorable set of conditions for developing a particular assay, method performance parameters are listed for each of the applications described. In all the above applications, the desired detection limits are met by adopting a broad range of strategies with the focus of keeping the method amenable to use at the point-of-care, i.e., ensuring that sample preparation is completed in <4 minutes. The proof-of-concept results obtained with the custom built Mini-12 mass spectrometer at Purdue University lays the groundwork to (i) encourage the introduction of miniature mass spectrometer-based assays for the molecules listed in a clinical setting and (ii) extend the use of miniature mass spectrometer-based assays for other therapeutic regimens that require longitudinal monitoring.</p>

The increased use of mass spectrometry in the clinical setting has led to a demand for high sample throughput. Developments such as ultra high performance liquid chromatography and the ambient ionization techniques enable high sample throughput by reducing chromatographic run times or by removing the requirement for sample preparation and fractionation prior to analysis. This thesis assesses the reproducibility and robustness of these high throughput techniques for the analysis of clinical and pharmaceutical samples by ion mobility-mass spectrometry. The rapid quantitative analysis of the urinary biomarkers of chronic obstructive pulmonary disease, desmosine and isodesmosine has been performed by ultra high performance liquid chromatography combined with ion mobility-mass spectrometry. The determination of health status based on the free unbound fraction rather than the total bound and unbound desmosine and isodesmosine, significantly reduces the time taken in sample preparation. The potential for direct analysis of the urinary metabolites from undeveloped TLC plates using a solvent extraction surface sample probe is demonstrated. The use of a solvent gradient for the extraction separates urinary metabolites from salts and other matrix components and allows fractionation of the sample as a result of differential retention on the undeveloped RP-TLC plate. This separation, combined with ion mobility-mass spectrometry provides a rapid ambient ionization method for urinary profiling. The combination of a thermal desorption probe with extractive electrospray ionization has been applied to the direct detection of a known genotoxic impurity from a surrogate active pharmaceutical ingredient. The volatility of the impurity compared to the matrix, allowed selective thermal desorption of the analyte, which was ionized by extractive electrospray and detected by mass spectrometry. The use of a rapid on-probe derivatisation reaction, combined with thermal desorption is demonstrated for the direct determination of urinary creatinine. The aqueous acylation of creatinine significantly increases the volatility of the analyte enabling separation from the urine matrix and analysis by thermal desorption extractive electrospray combined with ion mobility-mass spectrometry.

<p>The superior sensitivity and selectivity obtained with mass spectrometry (MS) is hardly matched by other analytical technologies, therefore it is an indispensable tool for modern society. Traditionally, MS is coupled with chromatography separation and performed in centralized analytical laboratories, which often requires extensive sample preparation and expensive instrumentation. With the advancements in the field of ambient MS and miniature MS, MS analysis at point-of-care (POC) has become a reality. Ambient MS includes a variety of methods for sampling and ionization, but they all share a common feature: they require little to no sample preparation. This has made rapid analysis of untreated sample possible and speed of MS analysis is significantly improved. Miniature MS, on the other hand, shrinks down the sizes of conventional benchtop instruments so they become portable or fieldable. In this dissertation, I documented the developments of ambient MS methods and applications of miniature MS for a variety of health-related topics, which include preclinical pharmacokinetics, intraoperative diagnosis, drug adherence monitoring and food safety. </p>

The ionization of chemicals in solids or liquids under ambient conditions, known as ambient ionization mass spectrometry, is currently a fruitful research area in mass spectrometry. To classify those ambient ionization techniques from preexisting atmospheric pressure ionization methods, the former are commonly defined as those mass spectrometric ionization methods that operate under ambient conditions and require minimal or no sample pretreatment. A characteristic of this technology is that sample introduction and ionization are usually separate events, thereby allowing independent control of each set of conditions. A two-step ESI-based technique, named electrospray laser desorption ionization (ELDI), has been developed to characterize nonvolatile analyte molecules directly from the surfaces of solid samples in 2005 by J. Shiea and his co-workers. The analyte molecules are produced by laser irradiating of the sample surfaces, and then post-ionized in an ESI plume. However, the pulsed laser used in ELDI-MS system is quite expensive. Our aim in this research is to develop simple, convenient, and cheap desorption methods and coupled them to post-ionization techniques for direct analysis of liquid and solid sample analysis. They includes: (a) the use of continuous wave (CW) laser instead of pulsed laser to desorb analytes in liquid samples and ointments, and (b) the use of thermal probe to desorb analytes in solid and liquid samples. All of the desorbed neutral species like molecules or droplets are then post-ionized via ESI or APCI processes. The first topic of the research is to develop a cheaper laser system to introduce analytes in solids or liquids into reaction region for post-ionization. In this section, we use a CW laser instead of a pulsed laser for the sampling of analytes. The titanium foil and stainless steel foil sample plate is quite useful and shows a great of desorption efficiency for liquid samples while irradiating by a CW laser. The detection limit by using a CW laser for sampling and ESI for post-ionization is 0.1 £gM for Benzethonium chloride and 1 £gM for cytochrome c, respectively. The combination of CW laser desorption and ESI post-ionization mass spectrometry can be applied in drug components, food safety and biomedical sample analysis. As a result of small size, lightness and lower prices of CW laser system, it not only shows large potential to use as a high efficiency desorption device for novel ionization source of mass spectrometer but also available for a wide range of useful application in many fields. The second topic of the research is to develop a new thermal probe for the direct desorption of sample surface. The home-made thermal probe is used to touch surface of solid sample or liquid sample to generate gas phase molecules or micro analyte droplets. Those neutral analytes are then post-ionized via ESI or APCI processes. In this study, the setting temperature of thermal probe is 250¢J. When the thermal probe touches liquid sample, it makes droplets boiling away explosively and then fused with ESI plume to generate ions. The detection limit by using a thermal probe for sampling and ESI or APCI for post-ionization is 1 £gM for both melamine and cytochrome c. This technique is also applied to analyze controversial additives in drinks. It also shows large potential to use as a high efficiency desorption device for novel ionization source of mass spectrometer and useful for a wide range of useful application in many fields.

A novel ambient ionization method which is so-called direct electrospray probe (DEP) has been developed in this study. This method provides rapid and high throughput analysis due to its advantages such as no sample pretreatment, low sample consumption, easily to change sample. In the study, we improved the interface of direct electrospray probe, and extend spray time to 1 minute for chemical analysis. Because of extending spray time, the method could be combined with principal component analysis (PCA), which is one kind of statistical method. Therefore, we applied the method for determination of alcoholic beverage which contains a lot of ions and alcohol. First, the conditions such as applying voltage, sample volume and shape of probe have been modified. The probes we used in the study were made by used metal pieces. These metal pieces with different thickness and tip angle to be test. Then, we found the optimize conditions as: voltage 7.0 kV, sample volume 3 £gL, thicknss of metal piece 0.1 mm, angle of metal piece 25 degree. Classification of 14 brands of wines which were purchased from supermarket was determined and analyzed by the method. Otherwise, we used the method to distinguish real wines from hedge wines we simulated. The hedge wines were prepared by adding flavor in alcohol solutions. Furthermore, we also used this method to observe fermentation process of wine production. Finally, deterioration of wine under exposure in air was also determined by the method. The results of the study demonstrated that the method we developed can be applied to distinguish hedge wines from real wines. And, it can used to monitor the fermentation process of wine production for quality control.

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.

Improvised explosive devices (IEDs) continue to be a national threat to the safety and security of the public. Research in explosives analysis for intact and post-blast samples continue to be a topic in which practitioners are constantly improving and searching for faster methods and techniques to analyze these sample types. The key role crime laboratories play in analyzing these sample types can have limitations, such as increasing turnaround times and backlogs. This concern additionally plays a role in the safety of the public if an unknown individual has not been discovered. Current analytical instrumentation in which explosives are analyzed includes Gas Chromatography – Mass Spectrometry (GC-MS), Liquid Chromatography – Mass Spectrometry (LC-MS), and Ion Mobility Spectrometry (IMS). Each instrument has benefits in the analytical results obtained. Direct Analysis in Real Time - Mass Spectrometry (DART-MS) has shown a significant promise as an analytical approach that can help remedy the time an explosive sample is analyzed, while additionally providing discriminating analytical results. Previous research has shown that DART-MS is capable of analyzing explosives, including smokeless powder. A limitation currently in the area of smokeless powder analysis with DART-MS is the application of utilizing this method and technology to realistic casework that may be encountered in forensic laboratories. Intact and post-blast explosive samples encountered in forensic laboratories arrive in various states and conditions. For example, the severity of the blast and environmental factors may play a role in the detection of smokeless powder on these sample types. To provide objective information and additional research, studies were conducted with mixture samples of smokeless powder and potential matrices that may be encountered in real world case samples. Faster processing time, in addition to the discrimination of smokeless powder, was the ultimate goal of this research. Due to the complexity of the mass spectra that may be generated from sample mixtures, an extraction technique coupled with DART-MS was investigated. A liquid-liquid extraction (LLE) method and dynamic headspace concentration using Carbopack™ X coated wire mesh were tested for the effectiveness of separating the analytes of interest of smokeless powder from various matrix interferences. Hodgdon Hornady LEVERevolution (HHL) smokeless powder, Pennzoil 10W-40 (P10W40) motor oil, and residue from metal end caps (China SLK brand) and black steel pipe nipples (Schedule 40) were used during the course of the matrix interference study. The method of applying dynamic headspace concentration using Carbopack™ X coated wire mesh and analysis by DART-MS provides an effective alternative to obtaining mass spectral data in a shorter amount of time, compared to techniques currently used in forensic laboratories. Effective separation was not achieved using the various LLE methods tested. Further testing would be required in order to evaluate the feasibility of implementing the technique as a sample preparation approach prior to analysis by DART-MS.

Orientador: Marcos Nogueira Eberlin / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-17T04:42:07Z (GMT). No. of bitstreams: 1 Simas_RosineideCosta_D.pdf: 5859215 bytes, checksum: bfba079c3f7e2a4ec510da69e7858d40 (MD5) Previous issue date: 2010 / Resumo: A caracterização química de óleos de forma rápida, eficiente e com mínimo preparo de amostras é um desafio para a química analítica moderna. Este estudo abrangeu a caracterização química de 15 amostras de óleos vegetais e 6 amostras de petróleo, e demonstrou a versatilidade da técnica de espectrometria de massas (MS) nesta área. A caracterização de óleos vegetais foi feita por uma técnica de ionização ambiente desenvolvida no Brasil, denominada Easy Ambient Sonic-Spray Ionization (EASI) e utilizando como analisador de massas um equipamento monoquadrupolar, que possui resolução unitária. Foi obtido, para os óleos vegetais, a sua composição de triacilglicerídeos (TAG), ácidos graxos livres e hidroperóxidos utilizando apenas uma gota de óleo e nenhum preparo de amostra. A análise direta de óleos vegetais possibilitou ainda propor um método quantitativo por EASI-MS para determinação do teor de triacilglicerídeos, que demonstrou concordância com os métodos de referência. Já a caracterização do petróleo empregou a altíssima exatidão e resolução da espectrometria de massas por ressonância ciclotrônica de íons com transformada de Fourier, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) com as técnicas de ionização EASI e Electrospray (ESI). O presente trabalho representou ainda a primeira tese de doutorado no Brasil em petroleômica, descrevendo um método de análise que dispensa uma série de procedimentos analíticos dispendiosos e demorados, de maneira a conferir um alto grau de refinamento e desempenho à análise de petróleo. Foram estudados os compostos polares do petróleo que contêm os heteroátomos nitrogênio (N), enxofre (S) e oxigênio (O) na sua composição, sendo possível caracterizá-los por distribuição em porcentagem de classes de heteroátomos, número de carbonos e insaturações por double bond equivalents (DBE). Foi apresentada uma proposta de estudo de precisão para a metodologia de petroleômica-MS por meio da estimativa de repetitividade e reprodutibilidade, além do estudo comparativo de eficiência das técnicas de ionização ESI e EASI / Abstract: The chemical characterization of oils in a fast way and with minimal sample preparation is a challenge for modern analytical chemistry. The present study comprised the chemistry characterization of 15 vegetal oil samples and 6 samples of petroleum, demonstrating the versatility of the mass spectrometry (MS) technique in this area. Vegetal oils characterization was performed by an ambient ionization technique developed in Brazil, named Easy Ambient Sonic-Spray Ionization (EASI), and using a monoquadrupole mass analyzer with unitary resolution. EASI-MS detected for vegetable oils the composition of triacylglycerols (TAG), free fat acids and hydroperoxides using only one drop of oil and without sample preparation. The direct analysis provided by EASI-MS allowed us to propose also a quantitative method based on EASI MS data to determine the level of triacylglycerols of the vegetal oils. This method was in agreement with reference methods. For petroleum characterization, we used ultra-high accuracy and resolution of the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with EASI and electrospray (ESI) ionization. The present work describes results from the first doctorate thesis in Brazil dealing with petroleomic MS, a method of analysis that precludes a series of expensive and time-consuming analytical procedures and that can confer a high degree of refinement and performance to petroleum analysis. We have studied polar components of the petroleum containing nitrogen (N), sulphur (S) and oxygen (O) as heteroatoms in their composition. These components were classified according to the percentage distribution of heteroatoms, carbon number and unsaturations, as well as double bond equivalent (DBE). The study also evaluated precision for petroleomic MS via estimations of repeatability and reproducibility. The efficiencies of ESI and EASI for the petroleum analysis were also compared / Doutorado / Quimica Analitica / Doutor em Ciências