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Development and application of NMR techniques to analyse complex mixtures

Grant number: 14/12776-6
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): September 01, 2014
Effective date (End): January 31, 2019
Field of knowledge:Physical Sciences and Mathematics - Chemistry - Organic Chemistry
Cooperation agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
Principal researcher:Roberto Rittner Neto
Grantee:Thaís Mendonça Barbosa
Home Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
Associated scholarship(s):15/19229-3 - Multi-way diffusion NMR data analysis applied to chemical reaction monitoring, BE.EP.DR


NMR is a powerful tool for chemical structure elucidation; however it is less used when dealing with complex mixtures, since it becomes hard to distinguish overlapping signals and to correlate signals to each chemical species under analysis. In NMR spectroscopy one of the most employed methods for intact mixture analysis is diffusion-ordered spectroscopy (DOSY). This method relays on differences in the diffusion coefficient of individual molecular species and typically a two-dimensional spectrum is used to disperse the signals in a diffusion dimension. In the most difficult scenery, when compounds show the same diffusion coefficient, which is often the case for mixtures of isomers or other cognate species, the use of a co-solute (a matrix), such as micelle forming surfactants, can allow these species to be distinguished by virtue of their different degrees of interaction with the matrix, altering the apparent diffusion coefficient, in a MAD (matrix-assisted DOSY) experiment. The very best resolution in the diffusion dimension is dependent on signals being well-resolved in the spectral dimension. Spectral resolution is directly related to the magnetic field strength. A large field spectrometer is very expensive, and even if you can afford the price there is a limit to what money can buy, even at the strongest commercially available field (1 GHz for 1H frequency) there is typically considerable overlap in spectra of mixtures and complex molecules. A central problem to signal overlap is the multiplicity caused by the homonuclear scalar coupling (J); 1H-homodecoupled or ''pure shift" NMR is an emerging class of experiments, suitable for DOSY and mixture analysis, that allow the suppression of the multiplicity and typically give a gain of almost an order of magnitude in spectral resolution. The standard DOSY processing (HR DOSY) is the most powerful when signals are well resolve, but breaks down when signals overlap. Here more advanced multivariate processing methods can be very valuable The major advantage of multivariate processing is that the whole dataset is used, which allows information from non-overlapped peaks to guide the separation of peaks that are overlapped. Recent developments using the OUTSCORE and ICA algorithms has improved the diffusion resolution by an order of magnitude, approaching that for well resolved signals. The big advantage of DOSY compared to the alternative of physical separation (e.g. LC-NMR) is that it allows non-invasive "chromatography" to obtain the clean spectrum for each component from the whole unperturbed mixture. This project will utilize, evaluate and further develop pure shift and diffusion NMR for several nuclei (i.e. 1H, 13C, 15N and 19F) in homo- and hetero-nuclear experiments to elucidate the structures of degradation products of commercial drugs obtained during acid/base stress testing, without previous sample separating. (AU)

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Scientific publications (6)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
BARBOSA, THAIS M.; CASTANAR, LAURA; MOUTZOURI, PINELOPI; NILSSON, MATHIAS; MORRIS, GARETH A.; RITTNER, ROBERTO; TORMENA, CLAUDIO F. Improving the Sensitivity of FESTA Methods for the Analysis of Fluorinated Mixtures. Analytical Chemistry, v. 92, n. 2, p. 2224-2228, JAN 21 2020. Web of Science Citations: 0.
BARBOSA, THAIS M.; VIESSER, RENAN V.; MARTINS, LUCAS G.; RITTNER, ROBERTO; TORMENA, CLAUDIO F. The Antagonist Effect of Nitrogen Lone Pair: (3)J(HF) versus (5)J(HF). ChemPhysChem, v. 19, n. 11, p. 1358-1362, JUN 5 2018. Web of Science Citations: 1.
CASTANAR, LAURA; MOUTZOURI, PINELOPI; BARBOSA, THAIS M.; TORMENA, CLAUDIO F.; RITTNER, ROBERTO; PHILLIPS, ANDREW R.; COOMBES, STEVEN R.; NILSSON, MATHIAS; MORRIS, GARETH A. FESTA: An Efficient Nuclear Magnetic Resonance Approach for the Structural Analysis of Mixtures Containing Fluorinated Species. Analytical Chemistry, v. 90, n. 8, p. 5445-5450, APR 17 2018. Web of Science Citations: 2.
BARBOSA, T. M.; MORRIS, G. A.; NILSSON, M.; RITTNER, R.; TORMENA, C. F. H-1 and F-19 NMR in drug stress testing: the case of voriconazole. RSC ADVANCES, v. 7, n. 54, p. 34000-34004, 2017. Web of Science Citations: 2.
BARBOSA, T. M.; RITTNER, R.; TORMENA, C. F.; MORRIS, G. A.; NILSSON, M. Convection in liquid-state NMR: expect the unexpected. RSC ADVANCES, v. 6, n. 97, p. 95173-95176, 2016. Web of Science Citations: 16.
BARBOSA, THAIS M.; VIESSER, RENAN V.; ABRAHAM, RAYMOND J.; RITTNER, ROBERTO; TORMENA, CLAUDIO F. Experimental and theoretical evaluation of trans-3-halo-2-hydroxy-tetrahydropyran conformational preferences. Beyond anomeric interaction. RSC ADVANCES, v. 5, n. 45, p. 35412-35420, 2015. Web of Science Citations: 6.
Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
BARBOSA, Thaís Mendonça. Nuclear Magnetic Resonance applied to fluorine-containing mixtures. 2019. 134 f. Doctoral Thesis - Universidade Estadual de Campinas (UNICAMP). Instituto de Química Campinas, SP.

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