Banca de DEFESA: JHONNY FRANK SOUSA JOCA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : JHONNY FRANK SOUSA JOCA
DATA : 20/04/2022
HORA: 13:00
LOCAL: Santo André
TÍTULO:

Preparation and Application Strategies of a Synthetic Multielemental Calibrating Material for Direct Analysis by LIBS

PÁGINAS: 203
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Analítica
ESPECIALIDADE: Métodos Óticos de Análise
RESUMO:

This work presents two strategies for the preparation of a synthetic multielemental calibrating material for direct analysis by LIBS. The extraction of the metals of interest from an aqueous solution using paraffin wax containing 1-(2-pyridyl-azo)-2-naphthol (PAN) proved to be feasible for the incorporation of Cd, Cr, Cu, Fe, Mn and Zn in the paraffin wax, that was shown by the quantification of these metals in the paraffin wax by ICP OES. The absence of significantly distinguishable signals from the analytical blank suggests some aspects related to laser-sample interaction hinder the atomization, excitation, and emission processes, making it impossible to obtain calibration curves and the subsequent application of the calibrating material. As an alternative to the extraction process, the use of beeswax as a substrate to produce calibrating material was evaluated. The incorporation of Conostan S-21 into beeswax allowed the preparation of standards containing between 6,90 e 150 μg g^-1 of the various elements present in the standard. After optimization of the LIBS system, calibration curves with excellent linearity were obtained for Al, B, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Si, Ti, V and Zn and, in addition to the external calibration, calibration strategies with 3 different internal standards (C I 505,50 nm line and C₂ bands at 516 and 545 nm), combined with the adjustment of the mineral oil content present in the calibrating material made it possible to quantify Fe, Mg, Si, Ti and Zn in lubricating oil and cosmetic products. The sample preparation process adopted was based on the dilution of these samples directly in molten beeswax, followed by the production of solid disks, which are analyzed by LIBS. The same samples analyzed by LIBS were analyzed by ICP-MS and ICP OES and the results are statistically comparable. The results open perspectives for the application of the calibrating material produced for the quantification of other analytes in other samples that can be incorporated into beeswax or its use in other techniques such as XRF or LA-ICP-MS.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1543683 - IVANISE GAUBEUR
Membro Titular - Examinador(a) Externo ao Programa - 271.444.448-24 - FLAVIO DE OLIVEIRA LEME - dpUNION
Membro Titular - Examinador(a) Externo ao Programa - 1548095 - PATRICIA DANTONI
Membro Titular - Examinador(a) Externo à Instituição - FABIO RODRIGO PIOVEZANI ROCHA - USP
Membro Titular - Examinador(a) Externo à Instituição - GEORGE LUIS DONATI - Wake Forest
Membro Suplente - Examinador(a) Interno ao Programa - 2145401 - DIOGO LIBRANDI DA ROCHA
Membro Suplente - Examinador(a) Externo à Instituição - RICARDO PEDRO - Fatec Diadem
Membro Suplente - Examinador(a) Externo à Instituição - PEDRO VITORIANO DE OLIVEIRA - USP