Analytical Techniques Development And Application
The thematic strand, Analytical techniques development and applications, is devoted to the implementation and development of new X ray spectrometry sources, and combining them with imaging techniques and molecular techniques bridging physics and chemistry to Biomedical Sciences, Art and Cultural Heritage research and toxicology fields in human being, in food and in forensic sciences.
The main challenges of this thematic strand are the advances in X-Ray Fluorescence spectrometry, with new sources and new applications and strengthen this elemental technique with molecular techniques for structural characterization.
The development of a compact portable spectrometer with doubly curved crystals (DCC), allowing monochromatic radiation permits the study in situ and in vivo of toxic elements like Pb, As, Cd and Hg.
These elements are toxic in concentrations of the order of ppb and are detected only in very special conditions. We also intend to use it for in vivo analysis, taking the advantage of the low dose delivered with such a system. The application in forensic sciences is demanding, considering the portability of the equipment and no sample preparation requirement.
X-ray fluorescence analysis is an important feature to predict concentrations from experimentally measured spectral intensities. These methods rely on the knowledge of physical parameters and calibrated standards for the type of samples to be analysed. We propose to develop a standardless method by the implementation of a Monte Carlo simulation to simulate calibrated standards instead of measuring them. This method will be extended to be applicable to inhomogeneous samples by the implementation of simulation routines aiming at 3D inhomogeneous samples spectra handling. This work will be carried out in collaboration with Technical University of Berlin and Sassari University in Italy.
As second point we intend to develop a bench top X ray system with a double monochromatic wavelength dispersive X-ray system. The basis for this instrumental advance is the use of two DCC systems, one for monochromatic excitation and another for monochromatic detection. Taking advantage of the bremsstrahlung radiation of high power X ray tubes it is possible to select the energy for the incident beam. The second DCC selects the energy of the emitted beam. For detector we intend to use a gas detector, specially developed by the instrumentation group, for this purpose.
This system is mainly devoted to study fundamental parameters, like intensity lines, satellite lines, line widths and the effect of chemical compounds in energy levels shift. We can easily select the element to study and choose the energy for the best excitation conditions. Due to the high resolution of the emission system we can assemble the high efficiency of the gas detectors on the detection system. At present, these studies are only possible by synchrotron radiation, and implementing its effectiveness in laboratory is noteworthy. This work is made in collaboration with Atomic Institute of Technical University of Vienna and Department of Chemistry, Atmospheric Science, University of Gothenburg in Sweden.
Dental Biomaterials study of photo-polymerization’s kinetics of several resins used for dental restorative work in order to compare the influence of the illumination time on the degree of conversion and its evolution in the time is another subject of work.
In biochemistry field we aim to explain the molecular changes that occur during the period of time following dental bleaching, in order to modify the treatment, to reduce the rate of treatment failures and also the inherent costs.
This is an ambitious research project to develop protocols and treatments in order to improve the resistance of the dental restorative work after whitening treatments.
Micro Particle Induced X-ray Emission and Micro Elastic Backscattering Spectroscopy are also used to study ancient coins since they are non-destructive and can determine the coin chemical fingerprint down to the ppm range. Collaboration with the Portuguese Mint House, will focuses the tribological improvement of coining dies for the Portuguese Mint by nitrogen implantation. Surface characterization will be carried out by ultramicrohardness indentation and Atomic Force Microscopy (AFM) and surface composition by Rutherford Backscattering Spectrometry (RBS). This work will provide analysis, certification, grading and encapsulation of coins. This set of procedures gives a technological boost in the field of numismatics with obvious synergies between science and society.
Environmental monitoring for some mining areas, food analysis, tissues of several organs of contaminated biological systems will be extended to new elements for increasing the knowledge of biological role of trace elements in the organism as a possibility for toxicocinetic modeling through the study of elemental concentrations. The involvement of some elements in the development of cancer, leading to the formation of free radicals or other reactive oxygen containing species, affecting adversely DNA and thereby causing cancer is a target of our study.
Links between X ray fluorescence spectrometry and Nutrition Sciences, Toxicology and Metrology in order to allow the spread of metrological principles and concepts into the chemistry food and nutrition will be strengthened. Its purpose is to provide an application of the latest advances on analytical techniques and bring together scientists and industry. Assembling specialists with different backgrounds and experiences will promote discussions and ideas exchange, through topics on traceability and dissemination, which is crucial to the work of researchers, students, regulators, policy makers, industry and public alike. Collaborations with Department of Materials Science and Engineering, Kyoto University and Laboratory of X-ray Analytical Applications Institute of Earth Sciences Jaume Almera, Barcelona, will be included in this research. The existing collaboration with São Paulo University in Brasil and Instituto Geológico e Mineiro in Portugal are also important partners in these studies.
One of the major activities of this thematic strand is devoted to Cultural Heritage. The portable and nondestructive developed X ray fluorescence systems will be used in situ, for preventive conservation studies, identification and characterization of Art Works from 16th to 18th mural paintings in degradation and contemporary master pieces and documents conservation-restoration processes. In this context multianalytical techniques are used in combination for complete diagnostic: SEM-EDS, Raman, FTIR and optical microscope. The existing strong collaborations with Museums, National Archives, Instituto Português de Conservação e Restauro and other private and public institutions devoted to conservation-restoration processes are the important point to note.
1. For the implementation of new X- Ray Spectrometry sources we intend to assemble a monochromatic wavelength dispersive X-ray fluorescence, which is a sensitive and selective method for elemental compositional analyses and fundamental applications. The basis is the doubly curved crystal optic, which offers an enabling technology for emerging portable, remote, and in-situ applications of monochromatic X-ray analysis for improved sensitivity.
This project will work in strong collaboration to Fundamental parameters development for quantitative calculations. Spectroscopic studies combining Raman, infrared and NMR techniques with modeling by quantum chemistry methods on neat ionic liquids and their mixtures with organic solvents are currently under progress in order to understand the solvation phenomena in complex media.
2. Cultural Heritage Research project intends to pursue the research with innovative instrumentation and approaches:
a) to study the mechanisms of corrosion in gold alloys objects for the development of conservation strategies in jewellery of cultural interest.
b) Characterization and study the plaster sculpture artistic heritage of 19th and 20th centuries of Faculdade de Belas Artes da Universidade de Lisboa. Some of this contemporary Art Works are in accelerated degradation and it is urgent to understand the behaviour of the new materials almost unknown to conservators.
c) Contribute for conservation-restoration of Mural paintings from 16th-18th centuries.
The optimisation of microanalytical non-invasive and non-destructive techniques will allow complementary research allowing a better interpretation of the technological and methodological evolution of pigments use.
d) Radiometric dating of metals validation by alpha spectrometry. It will allow determining the ore smelting date, and providing a secure basis for the application and development of the unique metal dating method proposed to date.
3. Oral Biology
In this project we intend to develop new treatment methodologies in combination to new materials, conducting to better explain the elemental and molecular changes in dental enamel following tooth bleaching procedures, in order to modify the treatment, to reduce the side effects in tooth structures and dental restorative procedures and also the inherent costs. The effects of reactive oxygen species (ROS) in the oral cavity are under study. Confocal micro-Raman will be used to detect the presence of ROS and the way it evolve in the crystals of hydroxyapatite of enamel, in particular the consequences for the organic matter present. X-ray Fluorescence will be used to obtain the elemental distribution at the enamel surface before and after tooth bleaching procedures. Both techniques are non destructive allowing to study the before/after effects.
4. Trace Elements in Biology, Forensic Sciences and Environmental Contamination monitoring will proceed. We intend to analyze soils and plants of abandoned mining areas of uranium, tungsten and copper to determine the trace element content. Edible and non-edible plants will be analyzed keeping in mind remediation purposes as well. Elemental mapping of the plants will be carried out in order to know the most affected areas of the plant.
With the new developed equipment, effort will be done to detect with high selectivity, sensitivity and accuracy some fraudulent practices. We intend to define some markers of identification in many high valuable products.
Healthy and disease human tissues will be studied for elemental concentration and mapping distribution for diagnostic and treatment purposes.
- The available techniques – X Ray Fluorescence spectrometry (XRFS), Raman microscopy, Particle Induced X Ray Emission (PIXE), Particle Induced Gama Ray Emission (PIGE) and Elastic Backscattering spectrometry (EBS) – will be applied in different fields of research. For this purpose, interdisciplinary collaborations have been settled and promoted. These collaborations include Biblioteca Nacional de Portugal, Arquivo Municipal de Lisboa, Instituto de Investigação das Pescas e do Mar, Instituto Português de Conservação e Restauro, Fundação Calouste Gulbenkian, Faculdade de Belas Artes da Universidade de Lisboa, Universidade de Évora, Câmara Municipal do Seixal and Câmara Municipal de Almada.
- Environmental monitoring for some mining areas, food analysis, tissues of several organs of contaminated biological systems will be extended to new elements for increasing the knowledge of biological role of trace elements in the organism as a possibility for toxicokinetic modelling.
- The analytical techniques will be also applied to the characterization of human tissues, both healthy and with pathologies with the purpose of contributing for diagnostic and treatment methodologies.
- The team will strength the application of XRFS to allow the spread of metrological principles and concepts into the chemistry food and nutrition. We intend to assemble specialists with different backgrounds and experiences to promote discussions and ideas exchange, through topics on traceability and dissemination, which is crucial to the work of researchers, students, regulators, policy makers, industry and public alike.
- XRFS will be combined the PIXE, PIGE, EBS, µ-Raman, techniques, supported by image processing algorithms, to detect forgeries in coins and study corrosion mechanisms in order to determine procedures to recover and preserve coins.
- XRF is a well-established laboratory technique and constitutes one of the few atomic spectroscopy techniques that can be used for portable instrumentation. According to a specific application, there are many factors that should be taken into consideration in the used setup in order to gather the maximum information in the final spectrum: the matrix of the sample, geometry of the setup, portability and the use of filtering and collimation, all with the objective of obtaining the best signal-to-noise ratio in the final spectrum. Taking this into consideration, our group devotes to the assembly and optimization of dedicated XRF spectrometers.
- We intend developing new equipment to improve the experimental conditions for the detection of trace elements, decreasing the detection limits, searching for new methodologies for in vivo
- In addition, is envisaged the development of new equipment with high energy resolution, as well as new software for quantitative analysis, opening new fields of research in speciation of heavy metals and study of trace elements with high sensitivity.
- It will be developed a compact portable spectrometer with doubly curved crystals, allowing monochromatic radiation that enables the study of toxic elements like Pb, As, Cd and Hg. It will be used, among others, for in vivo analysis, and in forensic sciences is demanding.