Banca de DEFESA: Marco Antonio de Souza

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Marco Antonio de Souza
DATE: 23/08/2022
TIME: 09:00
LOCAL: Auditório Azul - Instituto de Química
TITLE:

Development of analytical methods for detecting information, from endogenous and exogenous substances, in latent fingerprints using vibrational spectroscopy and nanosensors.

KEY WORDS:

Fingermarks, Raman spectroscopy, SERS, cocaine, infrared spectroscopy, sex determiantion, isotherm, nanoparticles, gold nanorods.

PAGES: 145
BIG AREA: Ciências Biológicas
AREA: Biologia Geral
SUMMARY:

This work aimed to develop methods for forensic informations from latent fingermarks (LF), from exogenous and endogenous substances, using vibrational spectroscopy. Regarding the methods of analysis of exogenous substances, it was possible to perform the qualitative detection of cocaine (COC) from LFs, using Surface Intensified Raman Scattering (SERS). For this, tests were performed with different SERS substrates of gold nanoparticles. The strategy adopted involved dripping these SERS substrates into aluminum blades. The adsorption of R6G and COC in aqueous solutions of different concentrations was studied, and the methodology was applied in the detection of COC in fingerprints. The COC used to prepare the solutions used for SERS studies was the corresponding hydrochloride salt. It was analyzed by 1H-NMR and its purity was determined as 88.27%. The substrate selected from the R6G tests was characterized. The UV-Vis results showed that the maximum absorption of cross-sectional surface plasmon resonances (LSPRT) at 545 nm and longitudinal (LSPRL) at 599 nm for AuNPs, confirming the presence of nanorods. In addition, stability was also observed through the analysis of UV-Vis measurements for a period of 28 days. The experimental data were adjusted to Langmuir, Frumkin and Freundlich isotherms, and Langmuir's data were best adjusted to the experimental data for COC and, according to DGads of -84.12 kJ/mol, it was possible to verify that the physical and spontaneous adsorption. In the contaminated fingerprint, it was possible to detect a concentration of the order of 10-4 mol/L, which corresponds to a mass of 273 ng. In addition to, it is sought to determine the gender of an individual, from endogenous substances of fingerprints, by means of Raman Spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR), with the aid of chemometric tools (Principal Component Analysis (PCA), Discriminant analyses by partial least squares (PLS-DA) ) and machine vector support (SVM-DA)). For Raman spectroscopy, discrimination rates varied between 80 and 93%, considering a period up to 7 days from the date of collection. For Raman measurements, the Supervised SVM-DA method proved to be more efficient. For FTIR, the PLS-DA results showed a discrimination rate of more than 80%.

BANKING MEMBERS:
Externo à Instituição - ANA CAROLLINE RIBEIRO DE TOLEDO PINTO
Interno - 1742174 - JULIANO ALEXANDRE CHAKER
Externo ao Programa - 1652361 - MARCELO HENRIQUE SOUSA
Externo à Instituição - MARCIO TALHAVINI
Externo à Instituição - RODRIGO MENESES DE BARROS