Banca de DEFESA: ADILSON DE SANTANA SANTOS
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : ADILSON DE SANTANA SANTOS
DATA : 04/12/2020
HORA: 08:30
LOCAL: Instituto de Química
TÍTULO:
PRODUCTION AND CHARACTERIZATION OF A LABORATORY REFERENCE MATERIAL FROM POWDERED MILK - QUALITY REQUIREMENT FOR INORGANIC ANALYSIS
PALAVRAS-CHAVES:
Certified reference, Powdered milk, multivariate analysis, simultaneous determination, HR-CS GF AAS.
Materiais de referência, leite em pó, análise multivariada, determinação simultânea, HR-CS GF AAS.
PÁGINAS: 125
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Analítica
ESPECIALIDADE: Análise de Traços e Química Ambiental
RESUMO:
Powdered milk and its derivatives are widely consumed worldwide, which requires the development of Reference Materials to assess the accuracy of the analytical methodologies that are used to analyze these food matrices. In this context, this study proposes the development of two studies: the first consists of the preparation and characterization of a Laboratory Reference Material (LRM) from powdered milk for inorganic analysis and the second aims at the simultaneous determination of chromium and iron in samples of this food using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). For the development of the LRM, the recommendations of ISO Guides 30-35 were met through the steps of homogeneity, stability, characterization, and uncertainty assessment. Through parameters obtained through the one-way analysis of variance (ANOVA) it was possible to affirm that the material is homogeneous and stable concerning Ca, Fe, K, Mg, Na, P, and Zn. As an alternative to ANOVA, multivariate analysis (PCA and HCA) was also applied to the data set and made it possible to extract a greater amount of information, such as that for Ca, K, Na, and P, in PC1, and Fe and Mg, in PC2, are the most responsible for the dispersion of results when a minimum mass of 100 mg was studied. The characterization study was established through an interlaboratory comparison with the participation of 15 laboratories, one international. The property values, as well as the combined uncertainty (URM) were as follows (mg g-1): Ca (8.795 ± 1.137), Fe (0.107 ± 0.017), K (11.727 ± 1.983), Mg (0.841 ± 0.125), Na (3.654 ± 0.672), P (7.572 ± 1.174), and Zn (0.032 ± 0.005). Therefore, the new material can be a good alternative to evaluate routine procedures, quality control, and validation of analytical methods related to samples of milk and dairy products. In the simultaneous determination, the primary resonance line chosen for Cr was 357.869 nm (the highest sensitivity for this element) and the secondary line (358.120 nm) for Fe, which are in the same spectral window of the detector. After the optimized conditions, five milk samples were analyzed and the chromium concentration found varied from 408 to 805 ng g-1. Among the five samples, three had an iron concentration lower than 19 µg g-1 and in the other two, the concentration varied from 151 to 191 µg g-1. Thus, the proposed method has precision, accuracy, and sensitivity for the determination of chromium and iron in milk samples.
MEMBROS DA BANCA:
Interno - 659.324.555-00 - MARCOS DE ALMEIDA BEZERRA - UFF
Interno - 286034 - ANA MARIA PINTO DOS SANTOS
Interno - 268481 - SERGIO LUIS COSTA FERREIRA
Interno - 285528 - VANIA PALMEIRA CAMPOS
Externo ao Programa - 6285989 - ANTONIO FERNANDO DE SOUZA QUEIROZ
Externo ao Programa - 2322888 - OLIVIA MARIA CORDEIRO DE OLIVEIRA
Externo à Instituição - IEDA SPACINO SCARMINIO