Determinação de boro, enxofre e fósforo em plantas medicinais por espectrometria de absorção atômica de alta resolução com fonte contínua
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Data
2013-02-19
Autores
Bechlin, Marcos André [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Este trabalho tem por objetivo a determinação do microelemento boro e dos macroelementos enxofre e fósforo em plantas medicinais por espectrometria de absorção atômica em chama de alta resolução com fonte contínua (HR-CS F AAS). Para a determinação do boro foram avaliadas duas linhas atômicas (λ1= 249,773 nm e λ2= 249,677 nm), para o enxofre duas linhas moleculares da molécula CS (λ1= 257,595 nm e λ2= 257,958 nm) e, para o fósforo três linhas moleculares da molécula PO (λ1= 246,400 nm; λ2= 247,620 nm e λ3= 247,780 nm). Para incrementar a sensibilidade na determinação de B, P e S, estudaram-se duas metodologias instrumentais: a integração da absorbância no comprimento de onda (WIA) e o somatório de absorbâncias. O aumento da área de integração mostrou ser mais eficiente no ganho de sensibilidade do que a estratégia do somatório de absorbâncias de diferentes linhas devido ao erro acumulado pela soma ser superior ao aumento do sinal analítico. As condições otimizadas de análise apresentaram limite de detecção de 0,5 mg L-1 (5,8 mg kg-1) e 13,7 mg L-1 (172 mg kg-1) nos comprimentos de onda 249,773 nm e 247,620 nm, com áreas de integração de 3 e 5 pixels, respectivamente, para B e P. Para S o menor limite de detecção foi obtido pela soma das absorbâncias e área de integração de 1 pixel, porém devido ao extenso tratamento de dados manual envolvido e o pequeno incremento em sensibilidade (10%), utilizou-se para as determinações a linha 257,595 nm com área de integração de 5 pixels que apresentou limite de detecção de 34,7 mg L-1 (440 mg kg-1). Titânio foi empregado como agente de liberação para impedir a interferência do cálcio na produção da molécula diatômica de PO. A avaliação da exatidão do método foi realizada pela análise de materiais certificados, cujos valores encontrados experimentalmente foram concordantes...
The goal of this work was the determination of the microelement boron and macroelements phosphorus and sulfur in medicinal plants by high-resolution continuum source flame atomic absorption spectrometry (HR-CS F AAS). For boron determination, two atomic lines were evaluated (λ1= 249,773 nm and λ2= 249,677 nm), to sulfur two molecular lines of CS molecule (λ1= 257,595 nm and λ2= 257,958 nm) and, to phosphorus three molecular lines of PO molecule (λ1= 246,400 nm; λ2= 247,620 nm and λ3= 247,780 nm). To improve sensitivity in the determination of B, P and S two instrumental methodologies were also studied, the wavelength integrated absorbance (WIA) and the summation of absorbance. The increase in integration area showed better results in gain of sensitivity in comparison to the sum of absorbance of different lines due to the accumulated error to be superior of the improvement in the analytical signal. The optimized conditions of analysis presented limit of detection of 0,5 mg L-1 (5,8 mg kg-1) and 13,7 mg L-1 (172 mg kg-1) on the wavelengths 249,773 nm and 247,620 nm, with integration areas of 3 and 5 pixels, respectively, for B and P. For S the best limit of detection was obtained for the sum of absorbance and integration area of 1 pixel, however, due to the laborious manual date treatment and the little increment in sensitivity (10%) the line 257,595 nm with integration area of 5 pixels was used to determinations, and presented limit of detection of 34,7 mg L-1 (440 mg kg-1). Titanium was employed as releasing agent to prevent the interference from calcium in the formation of the diatomic molecule of PO. The accuracy was evaluated by the analysis of two certified materials, experimental values were in agreement with certified values at 95% confidence level to P and S, and 98% confidence level to B. The methodology allows the determination of boron content in 11 samples... (Complete abstract click electronic access below)
The goal of this work was the determination of the microelement boron and macroelements phosphorus and sulfur in medicinal plants by high-resolution continuum source flame atomic absorption spectrometry (HR-CS F AAS). For boron determination, two atomic lines were evaluated (λ1= 249,773 nm and λ2= 249,677 nm), to sulfur two molecular lines of CS molecule (λ1= 257,595 nm and λ2= 257,958 nm) and, to phosphorus three molecular lines of PO molecule (λ1= 246,400 nm; λ2= 247,620 nm and λ3= 247,780 nm). To improve sensitivity in the determination of B, P and S two instrumental methodologies were also studied, the wavelength integrated absorbance (WIA) and the summation of absorbance. The increase in integration area showed better results in gain of sensitivity in comparison to the sum of absorbance of different lines due to the accumulated error to be superior of the improvement in the analytical signal. The optimized conditions of analysis presented limit of detection of 0,5 mg L-1 (5,8 mg kg-1) and 13,7 mg L-1 (172 mg kg-1) on the wavelengths 249,773 nm and 247,620 nm, with integration areas of 3 and 5 pixels, respectively, for B and P. For S the best limit of detection was obtained for the sum of absorbance and integration area of 1 pixel, however, due to the laborious manual date treatment and the little increment in sensitivity (10%) the line 257,595 nm with integration area of 5 pixels was used to determinations, and presented limit of detection of 34,7 mg L-1 (440 mg kg-1). Titanium was employed as releasing agent to prevent the interference from calcium in the formation of the diatomic molecule of PO. The accuracy was evaluated by the analysis of two certified materials, experimental values were in agreement with certified values at 95% confidence level to P and S, and 98% confidence level to B. The methodology allows the determination of boron content in 11 samples... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Quimica analitica, Plantas medicinais, Enxofre, Medicinal plants
Como citar
BECHLIN, Marcos André. Determinação de boro, enxofre e fósforo em plantas medicinais por espectrometria de absorção atômica de alta resolução com fonte contínua. 2013. 63 f. Dissertação (mestrado) - Universidade Estadual Paulista Júlio de Mesquita Filho, Instituto de Química, 2013.