Determinação do zinco em vegetais pelo método do zinconResumos
Este trabalho teve por objetivo o estudo do método de separação do zinco dos outros elementos por meio de resina trocadora de ânions (III, Merck), e a sua determinação colorimétrica por meio do Zincon, em vegetais. Estudou-se particularmente: 1 - estabilidade do complexo; 2 - formação do complexo em diversos pH; 3 - a influencia da concentração de ácido clorídrico na adsorção do zinco pela resina; 4 - efeito do volume de KC1 e NaNO3 na eluição do zinco ; 5 - influência de outros íons; 6 - exatidão e precisão do método; 7 - estudo comparativo de três métodos de preparo do extrato de vegetais.
This paper deals with the separation of zinc from other elements by means of anion exchange resin (Merck, III) and its colorimetric determination using zincon reagent, in plants. Some factors influiencing the method were studied such as: 1 - zinc-zincon complex stability; 2 - pH influence on the complex formation; 3 - interval of hydrocloric concentration for best absorption of zinc by the resin; 4 - effect of KC1 and NaNO3 solution volumes on the absorption and elution of zinc in the column; 5 - interference by other ions, specially those associated with zinc in vegetables; 6 - accuracy and precision of the zincon method; 7 - comparison of zinc estraction from the plant tissue by dry and wet ashing and fluorization, etc. The reagent is very stable but the color complex should be red within 30 minutes wheter developed in the light or in the dark. The volumes and concentration of reagents recomended by JOHNSON & ULRICH are good. Zinc is best absorbed by the resin in hidrocloric solution circa 2 normal. Other ions, usually found in plant analyses, in amounts from 10 to 100 or 500 micrograms did not interfer with 20 microgram of zinc. By comparison, repetition and recuperation it was observed that the present method is fairly accurate and well precise. Dry ashing gave results as good as the other 2 procedures; there was no statistical diference among them at the level of 5 %. The method may have no great accuracy for general application but is good enough for plant analysis.
Determinação do zinco em vegetais pelo método do zincon*
D. Pellegrino
E.S.A."Luiz de Queiroz"
RESUMO
Este trabalho teve por objetivo o estudo do método de separação do zinco dos outros elementos por meio de resina trocadora de ânions (III, Merck), e a sua determinação colorimétrica por meio do Zincon, em vegetais. Estudou-se particularmente:
1 - estabilidade do complexo;
2 - formação do complexo em diversos pH;
3 - a influencia da concentração de ácido clorídrico na adsorção do zinco pela resina;
4 - efeito do volume de KC1 e NaNO3 na eluição do zinco ;
5 - influência de outros íons;
6 - exatidão e precisão do método;
7 - estudo comparativo de três métodos de preparo do extrato de vegetais.
SUMMARY
This paper deals with the separation of zinc from other elements by means of anion exchange resin (Merck, III) and its colorimetric determination using zincon reagent, in plants. Some factors influiencing the method were studied such as:
1 - zinc-zincon complex stability;
2 - pH influence on the complex formation;
3 - interval of hydrocloric concentration for best absorption of zinc by the resin;
4 - effect of KC1 and NaNO3 solution volumes on the absorption and elution of zinc in the column;
5 - interference by other ions, specially those associated with zinc in vegetables;
6 - accuracy and precision of the zincon method;
7 - comparison of zinc estraction from the plant tissue by dry and wet ashing and fluorization, etc.
The reagent is very stable but the color complex should be red within 30 minutes wheter developed in the light or in the dark. The volumes and concentration of reagents recomended by JOHNSON & ULRICH are good. Zinc is best absorbed by the resin in hidrocloric solution circa 2 normal. Other ions, usually found in plant analyses, in amounts from 10 to 100 or 500 micrograms did not interfer with 20 microgram of zinc. By comparison, repetition and recuperation it was observed that the present method is fairly accurate and well precise. Dry ashing gave results as good as the other 2 procedures; there was no statistical diference among them at the level of 5 %.
The method may have no great accuracy for general application but is good enough for plant analysis.
Texto completo disponível apenas em PDF.
Full text available only in PDF format.
AGRADECIMENTOS
Testemunhamos nossos agradecimentos ao Professor Doutor Renato A. Catani pelo auxílio prestado e ao Doutor Pompilio de Abreu pelo cálculo estatístico.
Recebido para publicação em 8/8/1962.
Referências bibliográficas
- COWLING, H. & MILLER, H. J. - Determination of Small Amounts of Zinc in Plant Materials. Ind. and Eng. Chem. Anl. Ed. 13: 145, 1941.
- JACKSON, R.K. & BROWN, J. G. - The Determination of Zinc in Plant Material Without the Use of Organic Extractant. Proc. Amer. Soc. Hert. Sci. 68: 1, 1956.
- JOHNSON, CM. & ULRICH, A - Bull. Calif. Agric. Exper. Stat. 766: 71, 1959.
- KRAUS, K.A. & MOORE, G.E. - Anion Exchange Studies, VI. Acd. J. Amer. Chem. Sec. 75: 5. 1460, 1963.
- KRAUS, K. A. & NELSON, F. - Em Symposium on Ion Exchange and Chromatography In Analytical Chemistry. A. S. T. M. Spec. Tech. Publ. 195: 26, 1956.
- KUNIN, R. - Ion Exchange Resin. 2nd edition. New York, John Wiley & Sons. Inc. Publ., 1958.
- MARGERUM, D.W. & SANTACANA, F. - Evaluation of Methods for Trace Zinc Determination. Anal. Chem. 32( 9):1157, 1960.
- RUSH, R. M. & YOE, J. H. - Colorimetric Determination of Zinc and C Copper with 2-caboxy-2-hydroxy- 5- sulfoformazyl-benzene. Anal. Chem. 26(8): 1345, 1954.
- SANDELL, E.B. - Colorimetric Determination of Traces of Metals. 2nd. ed. New York, Interscience Publishers, 1950.
- SANUELSON, O. - Ions Exchangers in Analytical Chemistry. 3d printing. New York, John Wiley & Sons. Inc., 1956.
- YOE, J. H. & RUSH, R. M. - A New Colorimetric Reagent for Zinc. Anal. Chem. Acta. 6 (6):526, 1952.
Datas de Publicação
-
Publicação nesta coleção
11 Set 2012 -
Data do Fascículo
1962
