Banca de DEFESA: VIVIAN MARINGOLO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : VIVIAN MARINGOLO
DATE: 11/12/2023
TIME: 09:00
LOCAL: https://conferenciaweb.rnp.br/sala/diogo-57
TITLE:

Analytical procedures for the identification and monitoring of emerging pollutants and contaminants.

PAGES: 89
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Instrumentação Analítica
SUMMARY:

The presence of contaminants in foods and fuels requires constant monitoring through
chemical analyses, which can be performed quickly and accurately using automated
analytical procedures. The use of multi-energy calibration in spectrophotometry also
minimizes errors due to matrix effects, improving the accuracy of chemical analyses.
In this work, spectrophotometric multicommuted flow-based analytical procedures
were developed for sample preparation and for studying a new strategy for multi-signal
calibration in flow manifolds. Online dispersive liquid-liquid extraction followed by the
determination of free glycerol were performed in biodiesel. The analyte was transferred
to the aqueous phase under pulsed flow (10 s), and the organic phase was removed
with a column filled with glass fiber coupled to the system, which was regenerated with
50% ethanol after each determination. The aqueous phase was mixed with reagents
to form 3,5-diacetyl 1,4-dihydrolutidine (λMAX = 412 nm) from glycerol. Linear range
(LR), limit of detection (LOD), coefficient of variation (CV), and process efficiency were
estimated at 3.0-50.0 mg L-1, 2.0 mg L−1 (n = 20; confidence level of 99.7%), 4.2–6.0%
(n = 20), and 66%, respectively. An approach for multi-signal calibration, herein
denominated multi-dispersion calibration (MDC), was pioneeringly explored for
analytical purposes in flow systems for the determination of urea in milk. This strategy
was demonstrated with the spectrophotometric determination of urea in milk based on
enzymatic hydrolysis and subsequent color change of bromothymol blue (λMAX = 615
nm). Comparative analysis with MDC, external calibration and the reference methods
indicated the excellent performance of the strategy for analytical purposes. MDC was
also explored in the online spectrophotometric determination of bisphenol A using a
diazotization and coupling reaction. The estimated values of LR, LOD, and CV were,
respectively, 0.25-10 mg L-1, 0.057 mg L-1, and 4.0%. The three proposed procedures
yielded results of sample analysis consistent with those obtained by their respective
reference procedures (95% confidence). The methods are thus reliable alternatives for
the target determinations by exploiting the potentialities of flow systems for fast sample
preparation and application of multi-signal calibrations.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 2145401 - DIOGO LIBRANDI DA ROCHA
Membro Titular - Examinador(a) Interno ao Programa - 3047441 - MONICA BENICIA MAMIAN LOPEZ
Membro Titular - Examinador(a) Externo à Instituição - SIDNEI GONCALVES DA SILVA - UFU
Membro Titular - Examinador(a) Externo à Instituição - MILTON KATSUMI SASAKI - UFRGS
Membro Titular - Examinador(a) Externo à Instituição - ANDREIA CARDOSO PEREIRA - UFPA
Membro Suplente - Examinador(a) Interno ao Programa - 1543683 - IVANISE GAUBEUR
Membro Suplente - Examinador(a) Externo à Instituição - ANGERSON NOGUEIRA DO NASCIMENTO - UNIFESP
Membro Suplente - Examinador(a) Externo à Instituição - FABIO RODRIGO PIOVEZANI ROCHA