Determinação de bismuto por absorção atomica com geração de hidreto (BiH3) em um sistema de injeção em fluxo

AUTOR(ES)
DATA DE PUBLICAÇÃO

1991

RESUMO

Quality control of industrial products leads to continuous development and improvement of new chemical analytical methods. The presence of elements at trace levels requires instrumental methods which in turn can be automated. Trace amounts of bismuth can be found in clinical, metallurgical and environmental samples. Each matrix requires an efficient and fast analytical method which avoids a pre-concentration step; so that the time of analysis is not increased. Flow injection coupled to atomic absorption spectrometry with hydride generation detection accomplishes these requirements. A merging zones manifold was used in which 50 ml of both sample and reductor solution (1,0% NaBH4 ) were introduced into acid (1,0 M HCI) and water carriers, respectively. The generated bismuthine (BiH3) is separated from the liquid mixture in a stripping-type gas-liquid separator and transferred to an atomizer using N2 as purging gas. An absorbance signal proportional to bismuth concentration is produced when the hydride is atomized. Under the best conditions, the system is linear in the range of 0,1-100 ng Bi ml, with a detection limit of 320 pg Bi ml (corresponding to 16 pg Bi absolute) The relative standard deviation calculated for 20 determinations, varied from 10% for 1 ng ml up to 1,9% for 100 ng ml. The injection frequency was up to 150 h. An interference study showed that Ni(II), Co(II), Ag(I), Hg(II), Se(IV) and Sb(III) depressed the bismuth signal in more than 10%. This effect can be minimized using a mixture of 0,2% thiourea / 10% KI as masking agent. The proposed method gave satisfactory results when applied to medicines, urine, steels, non-ferrous alloys and sediment extracts.

ASSUNTO(S)

quimica analitica bismuto - analise

ACESSO AO ARTIGO

Documentos Relacionados