Banca de DEFESA: LUIS HENRIQUE DE QUEIROZ GUIMARAES
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.STUDENT : LUIS HENRIQUE DE QUEIROZ GUIMARAES
DATE: 15/06/2023
TIME: 13:30
LOCAL: Sala de seminários IQ
TITLE:
DETERMINATION OF OXITETRACYCLINE IN GROUNDWATER VIA RESONANT ENERGY TRANSFER (RET) PHENOMENON USING QUANTUM DOTS
KEY WORDS:
RET; Quantum dots; oxytetracycline; water analysis.
PAGES: 65
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Métodos Óticos de Análise
SUMMARY:
Antibiotics, such as oxytetracycline, are a group of emerging contaminants used in human and veterinary medicine and used as an additive in animal husbandry. Thus, its residues can be found in the most diverse matrices, such as food of animal origin and environmental samples, at trace and ultra-trace levels, requiring increasingly sensitive analytical methods. In this context, quantum dots (QD) stand out, acting as energy donors by resonance (Resonance Energy Transfer - RET) to other luminescent species, allowing the development of analytical methods with low limits of detection and quantification. The present work aims to evaluate the occurrence of RET between QD of CdTe coated with mercaptopropionic acid (MPA) and oxytetracycline (OTC) and its application in the determination of this antibiotic in groundwater samples. The RET investigation was performed by determining the donor/acceptor spectral overlap, quantum yield (ΦCdTe-MPA), and Föster critical radius R0. The developed method was optimized for medium pH and buffer composition. A significant increase in OTC emission (ΔF ≥90%) was observed in the presence of 3.2 nm nanocrystals, with displacement between the emission bands (~130 nm) of QD and analyte. Overlap of normalized OTC absorption and QD emission spectra (J(λ) = 1.012 x 1011 L nm4 mol-1 cm-1) was observed with high proximity between donor and acceptor (R0 = 0.0987 nm). Although the quantum yield of the donor (ΦCdTe-MPA = 49%) is within that reported in the literature, values of R0 < 1 nm indicate the non-occurrence of the phenomenon of FRET (Föster Resonance Energy Transfer) – long-range interactions, but a probable electronic transfer by the Dexter mechanism (short-range interaction). Finally, the method under optimal conditions presented LOD and LOQ of 0.086 and 0.262 μmol L-1, respectively, with an upper limit of the linear working range equal to 30.0 μmol L-1 (R = 0.99924, n = 8), with good sensitivity (13.321 intensity L μmol-1) and precision (RSD ≤ 1.2%; n=6, COTC =15 μmol L-1). The method showed good selectivity with a variation of less than 5% of the analytical signal for inorganic species commonly found in groundwater samples and TC, a molecule analogous to the analyte. Recovery percentages between 89 and 99% were obtained, indicating the accuracy of the proposed method. Thus, this method presents itself as a simple alternative for quantifying oxytetracycline at trace levels based on electronic energy transfer in water samples.
COMMITTEE MEMBERS:
Presidente - 1190574 - RODOLFO DE MELO MAGALHAES SANTANA
Interna - 282814 - MARIA DAS GRACAS ANDRADE KORN
Interno - 1649202 - LEONARDO SENA GOMES TEIXEIRA
Externo à Instituição - ANIBAL DE FREITAS SANTOS JUNIOR - UNEB
Externo à Instituição - MADSON DE GODOI PEREIRA