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Master's Dissertation
DOI
https://doi.org/10.11606/D.46.2019.tde-24102019-111452
Document
Author
Full name
Paulo Augusto Feldbaum
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2019
Supervisor
Committee
Oliveira, Pedro Vitoriano de (President)
Gaubeur, Ivanise
Rocha, Diogo Librandi da
Title in Portuguese
Determinação de terras raras em material geológico por ICP OES
Keywords in Portuguese
Elementos terras raras
ICP OES
Monazitas
Abstract in Portuguese
O objetivo deste trabalho foi o desenvolvimento de um método para determinações de Ce, La, Nd e Pr em material geológico por espectrometria de emissão óptica com plasma acoplado indutivamente (ICP OES). Durante o desenvolvimento do método foram empregadas amostras geológicas da região de Araxá/MG e também Material de Referência Certificado contendo monazitas (GRE-03 da empresa Geostats Pty Ltd). Foram realizadas otimizações nos parâmetros de operação do ICP OES para se obter as melhores condições para determinações dos analitos de interesse. Os métodos de preparo de amostra estudados foram a digestão ácida com H2SO4 e fusão alcalina com LiBO2, sendo este último o método escolhido para a etapa de preparo de amostra por apresentar melhores resultados. Foram realizados estudos dos comprimentos de onda a serem utilizados de modo a escolher aqueles que apresentassem a menor incidência de possíveis interferências espectrais. As linhas analíticas selecionadas foram Ce (II) 446,021 nm; La (II) 333,749 nm; Nd (II) 430,357 nm e Pr (II) 422,293 nm. As calibrações foram preparadas com a compatibilização de matriz (1500 mg Fe L-1 e 10,0 g LiBO2 L-1), de modo a minimizar o efeito da provável interferência de transporte devida à concentração de sais dissolvidos na amostra por conta do preparo por fusão. Resultados exatos (95% de confiança baseado no teste-t de Student) foram obtidos usando a calibração matrizada com 1500 mg Fe L-1 + 10 g LiBO2 L-1). Para a validação do método, além da exatidão, foram estudadas as figuras de mérito intervalo linear de trabalho, repetibilidade, reprodutibilidade, limite de detecção e limite de quantificação.
Title in English
Rare earths determination in geological material by ICP OES
Keywords in English
ICP OES
Monazites
Rare earth elements
Abstract in English
The objective of this work was the development of a method for determinations of Ce, La, Nd and Pr in geological material by inductively coupled plasma optical emission spectrometry (ICP OES). During the development of the method were used geological samples from the Araxá / MG region and also Certified Reference Material containing monazites (GRE-03 from Geostats Pty Ltd). Optimizations were made in the operating conditions of ICP OES to obtain the best conditions for determinations of the analytes of interest. The sample preparation methods studied were the acidic digestion with H2SO4 and alkaline fusion with LiBO2, the latter being the method chosen for the preparation stage of the sample because it presented better results. Studies of the wavelengths to be used were made to select those that presented the lowest incidence of possible spectral interferences. The analytical lines selected were Ce (II) 446.021 nm; La (II) 333.749 nm; Nd (II) 430.357 nm and Pr (II) 422.293 nm. The calibrations were prepared with matrix compatibilization (1500 mg Fe L-1 and 10.0 g LiBO2 L-1) in order to minimize the effect of probable transport interference due to the concentration of dissolved salts in the sample due to the preparation by Fusion. Exact results (95% confidence based on the Student ttest) were obtained using the calibration matrix with 1500 mg Fe L-1 + 10 g LiBO2 L-1). For the validation of the method, besides the accuracy, we studied the merit figures linear work interval, repeatability and reproducibility.
 
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Publishing Date
2019-11-14
 
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