Quantificação de baixos teores de selenio em alimentos por espectrometria de absorção atomica com atomização eletrotermica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

The determination of Se in food is a matter of analytical concern, because it is an essential micronutrient which may also be toxic, above a certain concentration. Aiming at such determination, ET AAS is one of the most widespread techniques that can be employed. However, the LD is frequently not adequate, considering that food samples usually have low Se contents. This work involves several studies with the objective of improving the determination of low concentrations of Se in food, by ET AAS. Firstly, a study on potential interferences was developed. It was demonstrated that a matrix effect occurs. Evidences were found that there are interactions between concomitants, for instance, Ca-P and Ca-Al. A comparison among several chemical modifiers was established. The best results were achieved using Rh as a modifier. Methods for Se preconcentration were developed and evaluated, in order to avoid the matrix effect and improve the LD. Two methods were suggested, which can be applied to food samples. The first one is based on the formation of the DDTC-Se complex, which is retained by Si-O2-C18. The complex is then eluted with ethanol and the eluate is collected for the determination of Se by ET AAS, using Rh chemical modifier. The second method, which is preferred, replaces DDTC with DDTP. This method was validated through the analysis of certified materials and by means of a national collaborative exercise. The procedure involves an EF equals to 65 and was optimised for Se determination in solid food samples having concentrations down to 0.05 mg kg Se.

ASSUNTO(S)

espectroscopia de absorção atomica selenio alimentos

ACESSO AO ARTIGO

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