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Major Research Areas @ ThoMSon Lab

1.Ion/molecule reactions

Reactions are the soul and heart of Chemistry. Gas phase ion/molecule reactions have a prominent capacity for structural characterization and for the study of reaction mechanisms. Ionic species in the gas phase or, alternately, neutral molecules may react, depending on their chemical reactivity, with ions of known structure. We at the ThoMSon lab have been using mainly pentaquadrupole mass spectrometry to perform gas phase ion/molecule reactions. Pentaquadrupoles display a variety of features that make such multiple satge mass spectrometers most suitable laboratories for studies of ion/molecule reactions, with exceptional gains in chemical information and selectivity.To learn more, read some of our key papers on this subject such as # 23, 26, 30, 124, 146 and books chapters.


2.Reaction Mechanisms in Solution

The study of reaction mechanisms in solution by mass spectrometry at the ThoMSon lab has involved mainly the use of electrospray ionization mass spectrometry (ESI-MS). These studies have provided a variety of detailed mechanistic information for different types of organic reactions performed in solution under their most common conditions. The speed, selectivity and sensitivity of ESI-MS(/MS) monitoring has turned this technique into an indispensable tool to investigate mechanisms of organic reactions. Snapshots of the ion composition obtained via rapid and continuous ion fishing’ during the course of the reaction provided by ESI-MS in the positive or negative ion modes, or both, and the characterization of the gaseous ionic species via on-line ESI-MS(/MS), have been shown to offer key information on the intermediates involved in major reaction steps. This information has probed established views or provided new or complementing mechanistic data that, in conjunction with data from other techniques, enable chemists to scrutinize such key processes in a fashion more deeply than ever before which allow us to “fish” intermediate species directly from the reaction solution to the gas phase. This fishing provides continuous snapshots of the ion composition of the solution and permits the characterization of even transient species. For a representative paper see # 129 and book chapters.


Figure 1. A cartoon of the ESI-MS “ion fishing” process for monitoring organic reactions in solution. Ions functioning as reactants, intermediates and products or neutral species in ionic forms are fished continuously from the reaction solution into the gas phase environment of mass spectrometers. In a view of its mechanisms, cations or anions are ejected (“explode out”) from the tinny charged droplets during ESI thus flying directly to the gas phase. Adapted from a carton available at http://www.thefishingline.com/ and signed by R. Stubler.


3. Coordination chemistry by ESI-MS

The technique of electrospray ionization-mass spectrometry (ESI-MS) is a relatively new and one of the most important tools for the characterization of metal complexes. These complexes are easily ionized and transferred to the gas phase, permitting their characterization by ESI- MS and ESI-MS/MS experiments. For a representative papers see # 110


4. Ionic liquids

ESI-MS(/MS) and its outstanding ability to transfer ions from the solution to the gas phase has enable us, mainly in collaboration with the research group of Prof. Jairton Dupont, to investigate the intrinsic properties of ionic liquids (IL) such as: formation and characterization of IL supra-molecular aggregates; formation, characterization and reactivity of multiply charged carbenes; distonic ions, charged bezynes and of the intrinsic strength of IL H bondings. For a representative paper see # 89.

5. Chemotaxonomic markers (lipids, sugars)

ESI-MS and also MALDI-MS, due to their simplicity and high selectivity, are powerful techniques for the identification of species markers for typification and quality control. We have applied ESI-MS and MALDI-MS to monitor chemotaxonomic markers in different matrices such as soybeans, toxins, and embryos. For a representative paper see # 356 and book chapters.

6. ESI-MS Fingerprinting

Direct infusion ESI-MS(/MS) has been shown to provide a powerful method to typify, control the quality, screen for adulteration and forgery, and to characterize and determine pureness of many products, without pre-separation or extensive sample preparation such as natural products (plant extracts, food), fuel, perfumes, and cleaning products. For a representative paper see # 108.


7. Proteomics & Peptidomics

MS has become an essential technique to characterize peptides, proteins and other biological relvant biomolecules and their complexes mainly via ESI-MS(/MS) and MALDI-MS(/MS) including peptide sequencing and the identification of the sites of post-translation modifications via CID, ETD and ECD. We have applied such techniques at the ThoMSon lab in peptidomics & proteomics MS studies, for a representative paper see # 93.


8. MS/MS Quantitation.

MS and particularly MS/MS in combination with GC and LC provide the most accurate and selective methods to quantitate active principles and markers in natural products, clinical and medicinal samples and other matrixes. The thoMSon lab has worked in this field suing by LC-MS/MS and high resolution GC-MS in different areas such as forensic, medical, drugs, phytotherapy and natural products. For a representative paper see # 337.

9. Forensic MS

Mass spectrometry, due to its outstanding speed, selectivity and sensitivity, has been a powerful technique for forensic investigations. In our laboratory, particularly via EASI-MS, we have been developing MS methods applicable to many forensic cases such as falsification of bank notes, fuels, ink and documents, food and drugs. For a representative paper see # 339.

Figure 1. Schematic of ambient MS fingerprinting of banknotes.  

10. TWIMS – Traveling Wave Ion Mobility Spectrometry

Ion mobility coupled to mass spectrometry has solved the greatest challenge in MS analysis: the resolution, quantitation and characterization of isomers including positional isomers and even enantiomers. The ThoMSon lab has been applying TWIMS using a SYNAPT instrument in a series of innovative procedures to separate isomers of many types as a function of their size, shape and charge. For the first paper on what seems to point for a long series see # 290.


11. Petroleomics

Petroleum is the most complex natural mixture known to date, and its myriad of chemicals offers one of the most challenging samples for chemical analysis. With the development of the revolutionary atmospheric pressure ionization (API) techniques, most particularly ESI, and its use in ultrahigh-resolution and ultrahigh-accuracy Fourier transform mass spectrometry (FTMS), MS has returned to its roots permitting direct characterization of crude oil samples without prior or on-line separation methods (known as petroleomic MS) having being able to detected heteroatom-containing (N,O,S) organic components of crude oils having more than 20K distinct elemental compositions. The ThoMSon lab, in collaboration with Petrobras and ANP, is performing Petroleomic FTMS studies to evaluate its application for crude oil production and processing using the most advanced Ultra LTQ FTMS instrument. For the first paper on what seems also to point for a long series see # 364.

Figure 1. Schematics for petroleomic by EASI-FTMS using the LTQ FTMS (ThermoScientific). A tiny droplet of the raw crude oil iks placed on a polyethylene film surface. A myriad of polar components (many thousands) are desorbed by the supersonic stream of minute charged methanol droplets, ionized and transferred to the ambient gas phase. A total of ca. 38 K oil components are detected and characterized mainly as either [M + H]+ or [M - H]- ions (blue dots) by ultrahigh resolution and ultrahigh accuracy FTMS.

12. Mew MS Techniques

The ThoMSon lab has also been very active in developing new MS techniques for chemical analysis, such as HS-MIMS, CT-MIMS, T&R-MIMS and, most recently, one of the most promising ambient mass spectrometric techniques: EASI-MS. For representative papers on this series see # 22, 54 and 284 and review articles.

Figure 1. On-spot EASI-MS characterization of HPTLC runs of biodiesel and biodiesel blends.