Avaliação do bismuto como padrão interno universal para determinação de chumbo por técnicas espectrométricas atômicas e de massas
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Data
2017-02-17
Autores
Bechlin, Marcos André [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Este trabalho tem por objetivo a avaliação do bismuto como padrão interno para a determinação de chumbo pelas seguintes técnicas: espectrometria de absorção atômica em chama de alta resolução e fonte contínua (HR-CS FAAS); espectrometria de absorção atômica em chama com fonte de linhas (LS FAAS); espectrometria de absorção atômica em forno de grafite com fonte de linhas (LS GFAAS); espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES); espectrometria de massas com plasma indutivamente acoplado (ICP-MS); vaporização eletrotérmica acoplada a espectrometria de massas com plasma indutivamente acoplado (ETV-ICP-MS) em amostras diversas. Bismuto mostrou-se eficiente na correção de variações instrumentais e interferências matriciais. Para avaliar a exatidão dos métodos desenvolvidos, foram analisados três materiais de referência certificados sendo os valores obtidos concordantes a 95% de confiança com o valor certificado (teste t) quando a padronização interna foi aplicada. Testes de adição e recuperação apresentaram recuperações de 74 – 231% (sem PI) para 96 – 109% (com PI) em HR-CS FAAS; de 52 – 118% (sem PI) para 97 – 109% (com PI) em LS FAAS; de 36 – 125% (sem PI) para 96 – 110% (com PI) em LS GFAAS; de 56 – 91% (sem PI) para 95 – 110% (com PI) em ICP OES; de 36 – 136% (sem PI) para 95 – 106% (com PI) em ICP-MS e de 5 – 123% (sem PI) para 92 -119% (com PI) em ETV-ICP-MS. Além da melhoria da exatidão o emprego do padrão interno melhorou também a precisão dos resultados: de 0,7 – 7,7% (sem PI) para 0,1 – 4,0% (com PI) em HR-CS FAAS; de 0,6 – 9,2% (sem PI) para 0,3 – 4,3% (com PI) em LS FAAS; de 1,5 – 9,9% (sem PI) para 0,4 – 5,9% (com PI) em LS GFAAS; de 0,8 – 9,0% (sem PI) para 0,2 – 5,8% (com PI) em ICP OES; de 0,5 – 11.3% (sem PI) para 0,1 – 6,6% (com PI) em ICP-MS e de 0,4 – 7,1% (sem PI) para 0,1 – 4,2% (com PI) em ETV-ICP-MS. Com os sinais obtidos nos experimentos de adição/recuperação foram construídos gráficos de correlação para avaliar o comportamento dos dois elementos frente às diferentes condições de análise sendo obtidos coeficientes de correlação de: 0,999 (HR-CS FAAS); 0,993 (LS FAAS); 0,981 (LS GFAAS); 0,968 (ICP OES); 0,996 (ICP-MS) e 0,989 (ETV-ICP-MS). Esses valores demonstram a semelhança no comportamento de Bi e Pb em todas as situações estudadas. Essa similaridade se deve a proximidade das propriedades físico-químicas e dos mecanismos de atomização, excitação e ionização dos dois elementos. As 34 amostras tiveram os teores de Pb determinados por ICP-MS e ETV-ICP-MS, sendo que os resultados foram concordantes ao nível de 95% de confiança (teste t pareado). Bismuto pode ser tido como um padrão interno universal para determinação de Pb em uma ampla gama de aplicações sendo efetivo na correção de variações instrumentais e interferências matriciais em FAAS, GFAAS, ICP OES, ICP-MS e ETV-ICP-MS, atendendo aos principais critérios de seleção de um padrão interno nas técnicas espectrométricas avaliadas.
The goal of this work was the evaluation of the bismuth as internal standard for lead determinations by the following techniques: high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS); line source flame atomic absorption spectrometry (LS FAAS); line source graphite furnace atomic absorption spectrometry (LS GFAAS); inductively coupled plasma optical emission spectrometry (ICP OES); inductively coupled plasma mass spectrometry (ICP-MS); electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) in assorted samples. Bismuth showed efficiently correction for instrumental variations and matrix shifts. To evaluate the accuracy of developed methods three certified reference materials were analyzed and the obtained results were in agreement at 95% confidence level (t-test) with the certified values. Further addition/recovery tests showed recoveries of 74 – 231% (without IS) to 96 – 109% (with IS) in HR-CS FAAS; 52 – 118% (without IS) to 97 – 109% (with IS) in LS FAAS; 36 – 125% (without IS) to 96 – 110% (with IS) in LS GFAAS; 56 – 91% (without IS) to 95 – 110% (with IS) in ICP OES; 36 – 136% (without IS) to 95 – 106% (with IS) in ICP-MS and 5 – 123% (without IS) to 92 -119% (with IS) in ETV-ICP-MS. Further the improvement in the accuracy, the employing of internal standard improve the precision of results from 0,7 – 7,7% (without IS) to 0,1 – 4,0% (with IS) in HR-CS FAAS; 0,6 – 9,2% (without IS) to 0,3 – 4,3% (with IS) in LS FAAS; 1,5 – 9,9% (without IS) to 0,4 – 5,9% (with IS) in LS GFAAS; 0,8 – 9,0% (without IS) to 0,2 – 5,8% (with IS) in ICP OES; 0,5 – 11.3% (without IS) to 0,1 – 6,6% (with IS) in ICP-MS and 0,4 – 7,1% (without IS) to 0,1 – 4,2% (with IS) in ETV-ICP-MS. With the analytical signals obtained in the addition/recovery experiments were built up correlation graphics to evaluate the behavior of the elements front of the different analytical conditions, the obtained correlation coefficients were: 0,999 (HR-CS FAAS); 0,993 (LS FAAS); 0,981 (LS GFAAS); 0,968 (ICP OES); 0,996 (ICP-MS) and 0,989 (ETV-ICP-MS). These values show the similarity in the behaviors of Bi and Pb in all the studied cases. These can be explained by the closeness of physical-chemical properties and mechanisms of atomization, excitation and ionization of Bi and Pb. Thirty-four samples were analyzed by ICP-MS and ETV-ICP-MS and the obtained Pb concentrations were in agreement at 95% confidence level (paired t-test). Bismuth can be stated as a universal internal standard for lead determinations in a large number of applications, been effective on the correction of instrumental variations and matrix interferences at FAAS, GFAAS, ICP OES, ICP-MS and ETV-ICP-MS, presenting the main selection criteria for the chosen of an internal standard for the evaluated spectrometric techniques.
The goal of this work was the evaluation of the bismuth as internal standard for lead determinations by the following techniques: high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS); line source flame atomic absorption spectrometry (LS FAAS); line source graphite furnace atomic absorption spectrometry (LS GFAAS); inductively coupled plasma optical emission spectrometry (ICP OES); inductively coupled plasma mass spectrometry (ICP-MS); electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) in assorted samples. Bismuth showed efficiently correction for instrumental variations and matrix shifts. To evaluate the accuracy of developed methods three certified reference materials were analyzed and the obtained results were in agreement at 95% confidence level (t-test) with the certified values. Further addition/recovery tests showed recoveries of 74 – 231% (without IS) to 96 – 109% (with IS) in HR-CS FAAS; 52 – 118% (without IS) to 97 – 109% (with IS) in LS FAAS; 36 – 125% (without IS) to 96 – 110% (with IS) in LS GFAAS; 56 – 91% (without IS) to 95 – 110% (with IS) in ICP OES; 36 – 136% (without IS) to 95 – 106% (with IS) in ICP-MS and 5 – 123% (without IS) to 92 -119% (with IS) in ETV-ICP-MS. Further the improvement in the accuracy, the employing of internal standard improve the precision of results from 0,7 – 7,7% (without IS) to 0,1 – 4,0% (with IS) in HR-CS FAAS; 0,6 – 9,2% (without IS) to 0,3 – 4,3% (with IS) in LS FAAS; 1,5 – 9,9% (without IS) to 0,4 – 5,9% (with IS) in LS GFAAS; 0,8 – 9,0% (without IS) to 0,2 – 5,8% (with IS) in ICP OES; 0,5 – 11.3% (without IS) to 0,1 – 6,6% (with IS) in ICP-MS and 0,4 – 7,1% (without IS) to 0,1 – 4,2% (with IS) in ETV-ICP-MS. With the analytical signals obtained in the addition/recovery experiments were built up correlation graphics to evaluate the behavior of the elements front of the different analytical conditions, the obtained correlation coefficients were: 0,999 (HR-CS FAAS); 0,993 (LS FAAS); 0,981 (LS GFAAS); 0,968 (ICP OES); 0,996 (ICP-MS) and 0,989 (ETV-ICP-MS). These values show the similarity in the behaviors of Bi and Pb in all the studied cases. These can be explained by the closeness of physical-chemical properties and mechanisms of atomization, excitation and ionization of Bi and Pb. Thirty-four samples were analyzed by ICP-MS and ETV-ICP-MS and the obtained Pb concentrations were in agreement at 95% confidence level (paired t-test). Bismuth can be stated as a universal internal standard for lead determinations in a large number of applications, been effective on the correction of instrumental variations and matrix interferences at FAAS, GFAAS, ICP OES, ICP-MS and ETV-ICP-MS, presenting the main selection criteria for the chosen of an internal standard for the evaluated spectrometric techniques.
Descrição
Palavras-chave
Chumbo, Bismuto, Padrão interno, Calibração, Técnicas espectrométricas