Full text
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| Author(s): |
Pedro dos Santos Moreau
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Química |
| Defense date: | 2021-12-13 |
| Examining board members: |
Marco Aurelio Zezzi Arruda;
Anne Hélène Fostier;
Valderi Luiz Dressler
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| Advisor: | Marco Aurelio Zezzi Arruda |
| Abstract | |
Dendrochemical studies allow the temporal evaluation of records, in the tree-ring series, of the environmental events that occur during the growing season of a tree. These records, verified from the chemical elemental distribution in the tree-rings series, carry information about the climate and environmental events, being this information important for the advance of the knowledge of the past climate and environmental events. The LA-ICP-MS technique has been shown to be very useful in this area of knowledge as it allows obtaining elementary information at the macro, micro, and even trace elements levels with spatial resolution at the micrometric scale. However, it is still a challenge to obtain quantitative information on tree-ring samples, since the LA-ICP-MS technique has inherent characteristics such as the dependence of the analytical signal on the matrix analyzed. Faced with this demand, and aiming purpose an analytical method that contributes with dendrochemical and paleoclimatic studies, the main objective of this master study is to develop a calibration method based on the use of filter paper as solid support, for the determination of Cu and Zn in tree-rings samples, using LA-ICP-MS. The method was based on the dispersion of a volume of 2.5 and 4.0 µL of elements standard solution in 8 mm diameter qualitative and quantitative filter paper discs, respectively, previously decontaminated. The calibration curves constructed for the monitored ions 65Cu+, 63Cu+, 64Zn+, and 66Zn+ presented a correlation coefficient varying between 0.991 and 0.999, for the data, both without and with the normalization of the signal using 13C as an internal standard. The limits of detection and quantification remained below 0.62 µg g-1 below and 1.33 µg g-1 for the monitored Zn e ions (except for the 66Zn+/13C+ specie which presented LQ of 3.11 µg g-1 for the qualitative filter), using both filters and with both types of data treatment. Regarding the validation of the method, the quantitative filter showed greater efficiency in matrix compatibilization, with recovery results for the studied CRMs of 79 – 116% and RSD of 4 – 16%, with data treated without normalization, since the signal normalization impacted on the decrease about 50% of the recovery percentage of the analytes determined on the CRMs. The analysis of the wood powder samples also showed that considering a compromise relationship, the quantitative filter paper was efficient for the elemental determination in most of the analytes in the two samples. It was then possible, using quantitative filter paper without signal normalization, under optimized conditions, to determine the concentration of Cu and Zn in samples of Hymenaea courbaril, Cavanillesia arborea, and Tipuana tipu, bringing quantitative information from the series of growth rings of such samples, allowing the observation of the pattern of variation of these inter-ring concentrations. The method has the potential to be applied in different dendrochemical and paleoclimatic studies, being a quick, simple, and cheap alternative to build calibration curves for LA-ICP-MS methods (AU) | |
| FAPESP's process: | 19/00018-3 - Study of inert supports as solid matrix for the quantification of Zn and Cu in tree rings and speleothems using LA-ICP-MS |
| Grantee: | Pedro dos Santos Moreau |
| Support Opportunities: | Scholarships in Brazil - Master |