Extração seletiva por ponto nuvem para pré-concentração e especiação de arsênio inorgânico em matriz alimentícia empregando espectrometria de absorção atômica eletrotérmica em forno de grafite
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Data
2013-07-29
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Universidade Federal de Goiás
Resumo
In this study, a highly sensitive and selective procedure for determination of arsenate and total arsenic in rice by electrothermal atomic absorption spectrometry after cloud point extraction As(V)-CPE-GF AAS was developed. The procedure is based on complex formation of As (V) ions with molybdate in the presence of 50.0 mmol L-1 sulfuric acid and 0.1 mmol L-1 ascorbic acid. The complex of As (V)-molybdate was extracted into the surfactant-rich phase of 0.06% w/v Triton X-114 solution. The variables affecting complex formation, extraction and phase separation such as complexing agent concentration, reducing agent concentration and electrolyte concentration were optimized using a factorial design and response surface methodology through central composite design (CCD). Under the optimal experimental conditions, the calibration graph was linear in the range of 0.03 – 10.0 μg L-1 for As (V) ions. The detection and quantification limits for As(V) were 0.0099 and 0.0331 μg L-1 respectively, obtaining an enrichment factor of 78.3 and the corresponding value for relative standard deviation (R.S.D) for 10 replicate determinations was below 5%. A two-level full factorial experimental design involving three factors (permanent modifiers, pyrolysis temperature PT and atomization temperature AT) was investigated to estimate the optimum values of the variables affecting the detection. It was demonstrated that iridium modifier and PT x AT interaction were considered in modeling the response surface. Recovery values were obtained between 90.8% and 113.1% for spiked samples. The method was successfully applied to the determination of As (V) and total arsenic in some rice samples.
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Arsênio, Extração por ponto nuvem, Arroz, Forno de grafite, Arsenic, Cloud point extraction, Food, ETAAS
Citação
COSTA, Bruno Elias dos Santos. Extração seletiva por ponto nuvem para pré-concentração e especiação de arsênio inorgânico em matriz alimentícia empregando espectrometria de absorção atômica eletrotérmica em forno de grafite. 2013. 85 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Catalão, 2013.