Estudo de modificadores quimicos e superficies modificadas para a determinação de estanho por espectrometria de absorção atomica com forno de grafite

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

Tin is an important element from an environmental viewpoint and is essential for humans at trace levels. However, the direct determination of tin by graphite furnace AAS has been fraught with problems such as volatilization loss, interaction with the graphite surface and sample matrix interference. In the present work, the use of the calcium, barium and strontium nitrate as chemical modifiers for tin determination, markedly increased the sensitivity for this element. Without a modifier the maximum pyrolysis temperature for tin was about 800°C, but with the addition of 20 mg of calcium, 30 mg of barium or 20 mg of strontium, the pyrolysis temperature increased to 1200 °C, 1000 °C and 1100 °C, respectively. Improvements in the atomization of tin are provided by treating the surface of the graphite platform with elements such as thorium, yttrium and zirconium which form refractory carbides. Modification of the surface of graphite atomizers has a number of advantages. In particular, it extended the lifetime and operational stability of the atomizer, reduced matrix effects and non-specific light absorption, increased the sensitivity and improved the precision of the data obtained. These systems were applied to the determination of tin in industrial effluents, synthetic seawater, municipal liquid waste samples and SRM-NIST certified standards.

ASSUNTO(S)

espectroscopia de absorção atomica estanho

ACESSO AO ARTIGO

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