Análise de especiação de arsênio por HG AAS com aprisionamento criogênico e uso de multiatomizador

• Ano de defesa: 2010
• Autor(a) principal: Moraes, Diogo Pompéu de
• Orientador(a): Flores, Érico Marlon de Moraes
• Banca de defesa: Seibert, Edson Luiz , Silva, Fabiana Ernestina Barcellos da , Barin, Juliano Smanioto , Paula, Favero Reisdorfer
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Santa Maria
• Programa de Pós-Graduação: Programa de Pós-Graduação em Química
• Departamento: Química
• País: BR
• Palavras-chave em Português: Análise de traços; Espectroscopia atômica; Geração química de vapor; Análise de especiação
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: http://repositorio.ufsm.br/handle/1/4185

In this work a procedure for arsenic speciation using criogenic trapping coupled to hydride generation atomic absorption spectrometry (HG-CT-AAS) was developed. Biological (chiken liver) and drug (N-methylglucamine antimonate)samples were investigated and the biological sample was introduced using slurry sampling to avoid the use of an extraction step. The material and the size of the cryogenic trapping tube ( U tube) were the parameters chosen to check the performance of the criogenic trapping step and arsenic species separation. The development of a new gas-liquid separator was also investigated. In addition, slurry concentration, foaming formed during the reaction with NaBH4, use of surfactant (Triton X-100) to achieve a homogenized particle distribution and the concentration of NaBH4 were studied. The results obtained using slurry sampling were compared with those using extraction with diluted phosphoric acid and tetramethylammonium hydroxide (TMAH) in different concentration. Water and biological tissue certified reference materials were used to evaluate the accuracy. The best separation efficiency of inorganic arsenic species, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and trimethylarsine oxide (TMAO) was achieved using a quartz U tube (305 mm of length, 2.5 mm i.d. and 24 mm of broad). Using 1% (m/v) NaBH4, 1% (m/v) anti-foaming and sample injection of 0.5 ml (slurry in the concentration of 10%, m/v), prepared in 0.5% Triton, the recovery for arsenic (in inorganic form) was 71.6 ± 2.3%. With the addition of 5% (m/v) TMAH in the slurry, the recovery was 75.4 ± 1.9%. It is important to point out that the recoveries obtained for the other arsenic species were similar in comparison with arsenic in inorganic form. Limits of detection (LOD) were 0.09, 0.03, 0.04 and 0.06 mg g-1 for inorganic As, MMA, DMA and TMAO, respectively. Using the proposed procedure by HG-CT-AAS it was possible to analyze four arsenic species with the respective oxidation state. However, due to low recoveries obtained, the procedure was not used as an alternative for arsenic speciation in biological samples using slurry sampling. Therefore, additional studies could be performed in order to obtain better results. The procedure HG-CT-AAS was also used for arsenic speciation in Nmethylglucamine antimonate (meglumine antimonate) drug. Initially, suppression in the analytical signal was observed due to high concentration of Sb in the matrix sample. Therefore, the use of citric acid (1 to 10%) and hydrogen (15 to 33 ml min-1) and oxygen (32 to 70 ml min-1) flow rate were studied to avoid SbH3 formation and, consequently, enhance the resistance towards atomization interferences due to more uniform filling of the optical tube volume with H-radicals. The development of a valve, positioned before the atomizer, to release the SbH3 formed, was used to reduce the interference. Using hydrogen (21 ml min-1) and oxygen (45 ml min-1) and the valve, recoveries of 94.9 ± 3.3, 103.3 ± 8.3, 95.3 ± 4.7 and 100.8 ± 3.1% were obtained for inorganic arsenic species, MMA, DMA, TMAO, respectively. In spite of good recoveries were obtained for all arsenic species studied, only the inorganic arsenic determination was performed, since other species were not observed in the drug samples. The results obtained for inorganic As(III) and As(V) in five samples by HGCT- AAS were compared with those obtained for total arsenic concentration obtained by inductively coupled plasma mass spectrometry (ICP-MS). In addition, inorganic As(III) and As(V) determination was performed by liquid chromatography (LC) coupled to ICP-MS. No statistic difference (t-test with confidence level of 95%) was observed between the results obtained for total As and As(III) e As(V), determined by HG-CT-AAS with those obtained by ICP-MS and LC-ICP-MS. The LOD for As determination in inorganic form using the proposed procedure was 0.11 mg l-1. Therefore, it was possible to determine As(III) and As(V), in the inorganic form, in low concentrations in the meglumine antimonate drug, since the Sb interference was avoided by HG-CT-AAS. In addition, the proposed procedure presents a relatively, low coast in comparison with other techniques used for arsenic speciation, as LCICP-MS.