Banca de DEFESA: HELLYDA KATHARINE TOMAZ DE ANDRADE SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : HELLYDA KATHARINE TOMAZ DE ANDRADE SILVA
DATE: 27/02/2023
TIME: 14:00
LOCAL: videoconferência
TITLE:

Development of analytical methodologies based on infrared spectroscopy and chemometrics applied to forensic entomology

KEY WORDS:

Taxonomic  categories;  NIR  spectroscopy;  ATR-FTIR  spectroscopy;  Sarcophagidae;  Entomotoxicology; Terbufos; Multivariate analysis

PAGES: 146
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Métodos Óticos de Análise
SUMMARY:

This thesis presents the development of alternative analytical methodologies based on near infrared spectroscopy (NIRS, from near infrared spectroscopy) and medium (ATR-FTIR, from attenuated total reflectance with Fourier transform infrared) combined with unsupervised chemometric techniques: principal component analysis (PCA) and hierarchical cluster analysis (HCA); variable selection and multivariate classification: principal component analysis with quadratic discriminant analysis (PCA-QDA), successive projections algorithm with quadratic discriminant analysis and genetic algorithm with quadratic discriminant analysis (GA-QDA) applied to forensic entomology. In the first study, NIRS was used for spectral acquisition of nine species of flies with forensic potential (Diptera: Calliphoridae and Sarcophagidae) in two regions of the insect (dorsal and ventral) with the subsequent construction of PCA and HCA models aiming to evaluate the potential methodology in the segregation/grouping of specimens into taxonom ic categories. The best model was achieved from the average dorsal and ventral spectra, observing the segregation of the species Chrysomya albiceps (Wiedemann, 1819), Lucilia eximia (Wiedemann, 1819) and Ravinia belforti (Prado & Fonseca, 1932), the resulting loadings punctuated absorptions associated with O-H, C-O, C-H and N-H stretches, the latter may be associated with chitin (poly-N-acetyl-glucosamine), the olefinic C-H stretches and fundamental for an unsaturated carbon associated with lipid compounds. In the dendrogram, a distinction was observed between specimens by family (Calliphoridae and Sarcophagidae) and genera (Chrysomya (Robineau-Desvoidy, 1830), Lucilia (Robineau-Desvoidy, 1830), Oxysarcodexia Townsend, 1917, Peckia (Wiedemann, 1830) and Ravinia (Robineau-Desvoidy, 1863)), whereas Oxysarcodexia and Peckia species did not present such established groups, but with considerable overlap. In the second study, ATR-FTIR was applied together with PCA-QDA, SPA-QDA and GA-QDA in discrimination of scavenger larvae (Diptera: Sarcophagidae) in groups: control and intoxicated after feeding on carcasses of rats exposed to the pesticide terbufos. The results showed that the proposed methodology has the potential to classify samples with sensitivity and specificity values greater than 90%. Amon g the three models, GA QDA was the best to detect changes in the biochemical composition of larvae exposed to terbufos, successfully classifying intoxication based on five variables and reaching 98.9% sensitivity and specificity. Therefore, the reported results suggest the potential of NIRS and ATR-FTIR spectroscopies combined with multivariate analysis as alternative tools to identify taxonomic properties of flies, such as family and genera, providing rapid evidence for species identity and in the detection of terbufos poisoning in scavenger fly larvae from carcasses of intoxicated rats, respectively.

COMMITTEE MEMBERS:
Externo à Instituição - EDVAN CIRINO DA SILVA - UFPB
Interno - 1803692 - FABRICIO GAVA MENEZES
Presidente - 1714946 - KASSIO MICHELL GOMES DE LIMA
Externo à Instituição - SIMÃO DIAS DE VASCONCELOS FILHO - UFPE
Externa ao Programa - 1523912 - TATIANA DE CAMPOS BICUDO - null