Desenvolvimento de método analítico para a determinação de vanádio em material vegetal por espectrometria de absorção atômica em forno de grafite
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Data
2007-06-25
Autores
Ambrozini, Beatriz [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os modificadores químicos W, Rh e BaF2 foram avaliados no desenvolvimento de método analítico para a determinação de vanádio em material vegetal por espectrometria e absorção atômica simultânea em forno de grafite. O comportamento térmico do vanádio foi estudado por meio de curvas de temperatura de pirólise e de atomização em meio de uma matriz composta pela suspensão de fragmentos de folhas ou raízes de plantas de salsinha (Petroselinum sp). Os melhores comportamentos de vanádio foram observados quando não se usa modificador e para o BaF2. Curvas analíticas (0,0 a 50 æg L-1 V) construídas por compatibilização de matriz forneceram boas correlações lineares (r2= 0,9989). As concentrações de vanádio em salsinhas cultivadas via hidroponia variaram de 0,69 a 2,23 ?g g-1. Os resultados obtidos para o material vegetal analisado com e sem modificador foram concordantes ao nível de 95% de confiança.Os limites de detecção (LOD) foram 0,94 e 0,74 ?g L-1, sem e com modificador, respectivamente. O desvio padrão relativo (r.s.d) foi 4,2% (sem modificador) e 2,6% (BaF2) e as respectivas massas características foram 17 pg V e 15,8 pg V. Dois materiais de referência certificados da National Institute of Standards and Technology (Tomato leaves 1573a e Spinach Leaves 1570a) foram analisados e os valores encontrados foram concordantes ao nível de 95% de confiança com os valores certificados. A validação dos métodos desenvolvidos envolveu o emprego do estudo de adição e recuperação de padrão. As recuperações variaram de 93 a 108% e de 88 a 102%, sem e com modificador, respectivamente. O emprego de BaF2 não eliminou os efeitos de memória causados pela formação de carbetos de vanádio refratários na plataforma do tubo de grafite.
Diferent chemical modifiers were evaluated at the development of analytical method to determinate vanadium in garden parsley samples enriched with vanadium by hydroponic system by graphite furnace atomic absorption spectrometry (GF AAS) technique. The electrothermal behavior of V was studied by means of pyrolysis and atomization temperature curves in the garden parsley matrix. The evaluated modifiers were: W, Rh, BaF2 and modifier absence. The V better behaviors were observed for the BaF2 modifier and in the absence of modifier, once they presented better transient signal profiles, better r.s.d and better characteristic masses were obtained. Analytical curves were built within 0,0-50,0 æg L-1 interval using matrix matching calibration. Digest samples were employed to help the validation of the method. The V concentrations at the aerial parts of the garden parsley varied from 0,7 to 2,23 æg g-1 and from 0,69 to 2,21 æg g-1, in the modifier absence and in the presence of BaF2, respectively. The limit of detection (LOD) were 0,94 and 0,74 æg L-1, in the modifier absence and in the presence of BaF2, respectively. The characteristic mass were 17 pg V and 15,8 pg V, in the modifier absence and in the presence of BaF2, respectively. The relative standard deviation (r.s.d.) was _ 4,2 % in the modifier absence and _ 2,6% in the presence of BaF2. At the roots of the enriched garden parsley, the concentrations varied from 2,93 to 3,44 æg g-1 V and from 2,92 to 3,43 æg g-1 V, without and with modifier, respectively. The limit of detection (LOD) were 0,64 and 0,70 æg L-1, in the modifier absence and in the presence of BaF2, respectively. The relative standard deviation (r.s.d.) was _ 3,3 % and _ 2,3%, in the modifier absence and in the presence of BaF2, respectively. A paired t-test showed that results between all methods were in agreement at 95% confidence level. Two standard reference materials from the National Institute of Standards and Technology...
Diferent chemical modifiers were evaluated at the development of analytical method to determinate vanadium in garden parsley samples enriched with vanadium by hydroponic system by graphite furnace atomic absorption spectrometry (GF AAS) technique. The electrothermal behavior of V was studied by means of pyrolysis and atomization temperature curves in the garden parsley matrix. The evaluated modifiers were: W, Rh, BaF2 and modifier absence. The V better behaviors were observed for the BaF2 modifier and in the absence of modifier, once they presented better transient signal profiles, better r.s.d and better characteristic masses were obtained. Analytical curves were built within 0,0-50,0 æg L-1 interval using matrix matching calibration. Digest samples were employed to help the validation of the method. The V concentrations at the aerial parts of the garden parsley varied from 0,7 to 2,23 æg g-1 and from 0,69 to 2,21 æg g-1, in the modifier absence and in the presence of BaF2, respectively. The limit of detection (LOD) were 0,94 and 0,74 æg L-1, in the modifier absence and in the presence of BaF2, respectively. The characteristic mass were 17 pg V and 15,8 pg V, in the modifier absence and in the presence of BaF2, respectively. The relative standard deviation (r.s.d.) was _ 4,2 % in the modifier absence and _ 2,6% in the presence of BaF2. At the roots of the enriched garden parsley, the concentrations varied from 2,93 to 3,44 æg g-1 V and from 2,92 to 3,43 æg g-1 V, without and with modifier, respectively. The limit of detection (LOD) were 0,64 and 0,70 æg L-1, in the modifier absence and in the presence of BaF2, respectively. The relative standard deviation (r.s.d.) was _ 3,3 % and _ 2,3%, in the modifier absence and in the presence of BaF2, respectively. A paired t-test showed that results between all methods were in agreement at 95% confidence level. Two standard reference materials from the National Institute of Standards and Technology...
Descrição
Palavras-chave
Quimica analitica, Vanadio, Petroselinum sp, GFAAS, Suspensão
Como citar
AMBROZINI, Beatriz. Desenvolvimento de método analítico para a determinação de vanádio em material vegetal por espectrometria de absorção atômica em forno de grafite. 2007. 118 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Química, 2007.