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Abstract(s)
No presente trabalho desenvolveu-se uma metodologia para implementação e validação da técnica de Espectrometria de Massa com Plasma Indutivo Acoplado (ICP-MS) para determinação de metais em águas de consumo humano com a finalidade de ser usada em rotina no Laboratório de Águas e Efluentes do CITEVE. O método desenvolvido envolve a análise simultânea de Be, B, Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, Ba, Pb e U.
Em ICP-MS, os iões poliatómicos originados no plasma (Ar), no ar circundante (C, N e O), no solvente (O e H) e na matriz das amostras (por ex: S, Cl, Na, K, Ca e Mg) produzem interferências espectrais nos isótopos que possuem a mesma razão massa/carga, causando um desvio positivo nos resultados. Estas interferências não podem ser separadas dos analitos de interesse devido a uma resolução insuficiente do quadropolo.
O método usado para correcção de interferências espectrais foi o uso de equações matemáticas de correcção. Foram determinados experimentalmente os factores de correcção das equações matemáticas, para serem aplicadas nas massas onde foram detectadas interferências por análise de soluções de interferentes na ausência de analito.
Os resultados de precisão e exactidão obtidos durante a validação demonstram que o desempenho do método analítico desenvolvido se encontra de acordo com os requisitos da Directiva Europeia 98/83/CE no que respeita a monitorização de metais em águas de consumo humano.
Os resultados das análises de arsénio em algumas amostras de águas destinadas ao consumo humano, provenientes da rede pública, demonstraram que é necessário um tratamento eficaz da água que chega à torneira do consumidor bem como da sua vigilância permanente através de análises quantitativas periódicas.
A methodology for the implementation and validation of a method for determination of metals in drinking waters by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was developed in the present work, with the purpose to be used in routine analysis in CITEVE laboratory of water and wastewater. The method developed involves simultaneous analysis of Be, B, Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, Ba, Pb and U. In ICP-MS, polyatomic ions originated from the plasma (Ar), the air surrounding the plasma (C, N e O), the solvent (O and H) and in the sample matrix (e.g. S, Cl, Na, K, Ca and Mg) produce spectral interferences on isotopes of the same nominal mass and positive bias on the results. These interferences cannot be separate from the masses of interest due to an insufficient resolution of the quadrupole. The methodology chosen to overcome polyatomic interferences was the use of elemental equations and mathematical correction. Estimation of the correction factors for the equations was experimentally determined measuring an interference check solution in the masses affected by interferences, in the absence of the analyte. The precision and accuracy of the analytical method were determined. The results obtained demonstrated that the performances of the developed analytical method are in agreement with the requirements of the European Directive 98/83/CE concerning metals monitoring in drinking waters. The results obtained for arsenic in public network water samples, collected from the taps of the consumers, demonstrate that it is necessary an efficient treatment of water for this substance, as well as a regular monitoring by quantitative analysis.
A methodology for the implementation and validation of a method for determination of metals in drinking waters by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was developed in the present work, with the purpose to be used in routine analysis in CITEVE laboratory of water and wastewater. The method developed involves simultaneous analysis of Be, B, Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Sn, Sb, Ba, Pb and U. In ICP-MS, polyatomic ions originated from the plasma (Ar), the air surrounding the plasma (C, N e O), the solvent (O and H) and in the sample matrix (e.g. S, Cl, Na, K, Ca and Mg) produce spectral interferences on isotopes of the same nominal mass and positive bias on the results. These interferences cannot be separate from the masses of interest due to an insufficient resolution of the quadrupole. The methodology chosen to overcome polyatomic interferences was the use of elemental equations and mathematical correction. Estimation of the correction factors for the equations was experimentally determined measuring an interference check solution in the masses affected by interferences, in the absence of the analyte. The precision and accuracy of the analytical method were determined. The results obtained demonstrated that the performances of the developed analytical method are in agreement with the requirements of the European Directive 98/83/CE concerning metals monitoring in drinking waters. The results obtained for arsenic in public network water samples, collected from the taps of the consumers, demonstrate that it is necessary an efficient treatment of water for this substance, as well as a regular monitoring by quantitative analysis.
Description
Keywords
Espectrometria Espectrometria de massa - Água - Controlo de qualidade Água - Qualidade - Método de análise