Potencialidades analíticas do dietilditiofosfato de amônio em espectrometria de massas com plasma indutivamente acoplado empregando extração em fase sólida e sistemas de injeção em fluxo
Nenhuma Miniatura disponível
Data
1999-01-01
Autores
Gomes Neto, José Anchieta [UNESP]
Curtius, Adilson José
Dressler, Valderi Luís
Título da Revista
ISSN da Revista
Título de Volume
Editor
Editora Unesp
Resumo
Um sistema de injeção em fluxo envolvendo complexação com dietilditiofosfato de amônio e sorção de complexos metálicos em minicolunas de sílica gel modificada por grupos octadecil C18 é proposto para determinações multielementares em espectrometria de massa com plasma indutivamente acoplado. Influência da concentração de reagentes, natureza do ácido, tempo de reação, tempos de comutação, vazões e interferência de sódio foram investigadas. Água ou solução 2% v/v HNO3 podem ser utilizadas para lavar a coluna antes da eluição dos analitos com etanol. Amostras contendo 5000 mg Na L-1 e analisadas diretamente com o sistema proposto produzem uma concentração aparente de 63Cu de 0,45 µg L-1; por outro lado não foi observada interferência para As, Pb, Bi, Se, In, Tl, Cd, Hg e 65Cu. Para 0,25 % w/v NH4DTP e 3 mL de solução de amostra, curvas analíticas para Bi, Cu, Pb, As, Se, In, Tl, Cd, Hg no intervalo de 0,10 a 2,00 µg L-1 podem ser construídas com boas correlações (r2 > 0.998). A velocidade analítica e sensibilidade podem ser melhoradas pois dependem das condições de pré-concentração e eluição selecionadas. Com os parâmetros acima fixados, limites de detecção de 0.014 (Cu), 0.027 (As), 0.06 (Se), 0.02 (Cd), 0.029 (In), 0.043 (Hg), 0.02 (Tl), 0.06 (Pb) e 0.002 µg L-1 (Bi) foram obtidos.
Complexation with ammonium diethyl dithiophosphate and sorption on a C18 bonded silica gel minicolumn in flow system was exploited for on-line separation and preconcentration in inductively coupled plasma mass spectrometry. Influence of interaction time between metallic ions and ligand, ligand concentration, nature and concentration of acid, timing, flow rates and minimization of spectral interference due to sodium were studied. Metallic complexes were stripped from the solution and retained in the minicolumn. Other ions that do not form complexes pass through the column promoting the separation of the matrix. Selectivity was improved with sequential elution. Water or 2% v/v HNO3 solution can be used for minicolumn washing before analyte elution with ethanol. When samples with sodium content up to 5000 mg L-1 were directly analysed in system, 63Cu apparent concentration of only 0.45 µg L-1 was detected while no interference were observed for As, Pb, Bi, Se, In, Tl, Cd, Hg and 65Cu. For 0.25 % of ligand solution and 3 mL sample volume in 2 % (v/v) HNO3, analytical curves for Bi, Cu, Pb, As, Se, In, Tl, Cd, Hg in the 0.10-2.00 µg L-1 range were obtained (r > 0.998). Sampling rate and detection limit depend on the selected conditions for concentration and elution. Detection limits for Cu, As, Se, Cd, In, Hg, Tl, Pb, and Bi were 0.014, 0.27, 0.06, 0.02, 0.29, 0.43, 0.02, 0.06 and 0.002 µg L-1, respectively.
Complexation with ammonium diethyl dithiophosphate and sorption on a C18 bonded silica gel minicolumn in flow system was exploited for on-line separation and preconcentration in inductively coupled plasma mass spectrometry. Influence of interaction time between metallic ions and ligand, ligand concentration, nature and concentration of acid, timing, flow rates and minimization of spectral interference due to sodium were studied. Metallic complexes were stripped from the solution and retained in the minicolumn. Other ions that do not form complexes pass through the column promoting the separation of the matrix. Selectivity was improved with sequential elution. Water or 2% v/v HNO3 solution can be used for minicolumn washing before analyte elution with ethanol. When samples with sodium content up to 5000 mg L-1 were directly analysed in system, 63Cu apparent concentration of only 0.45 µg L-1 was detected while no interference were observed for As, Pb, Bi, Se, In, Tl, Cd, Hg and 65Cu. For 0.25 % of ligand solution and 3 mL sample volume in 2 % (v/v) HNO3, analytical curves for Bi, Cu, Pb, As, Se, In, Tl, Cd, Hg in the 0.10-2.00 µg L-1 range were obtained (r > 0.998). Sampling rate and detection limit depend on the selected conditions for concentration and elution. Detection limits for Cu, As, Se, Cd, In, Hg, Tl, Pb, and Bi were 0.014, 0.27, 0.06, 0.02, 0.29, 0.43, 0.02, 0.06 and 0.002 µg L-1, respectively.
Descrição
Palavras-chave
Dietilditiofosfato de amônio, minicoluna de sílica C18, análises por injeção em fluxo, espectrometria de massa com fonte de plasma indutivamente acoplado, Ammonium diethyl dithiophosphate, C18 bonded silica gel, flow-injection analysis, inductively coupled plasma mass spectrometry
Como citar
Eclética Química. Fundação Editora da Universidade Estadual Paulista Júlio de Mesquita Filho - UNESP, v. 24, p. 69-89, 1999.