Sôbre a determinação do nitrogênio, do fósforo e do potássio no mesmo extrato

Malavolta, E.; Arzolla, J. P.; Haag, H. P.

doi:10.1590/S0071-12761958000100002

Resumo

The determination of total nitrogen, phosphorus, and potassium in plant material can be carried out in a common extract prepared with sulphuric acid and 30 per cent hydrogen peroxide. Nitrogen is estimated by direct nesslerization of a suitable aliquot (1-5 ml of the 50 ml extract made out of 250 mg of dried material); in order to avoid excessive acidity, 10 ml of Nessler's reagent should be employed. An aliquot of 1-5 ml suffices for the colorimetric determination of phosphorus by the molybdenum method; to reduce the phosphomolybdate complex 2 ml of a 2% SnC12 soln are necessary. Potassium is determined by the cobaltinitrite method after elimination of ammonium salts with the aid of aqua-regia.

Cadeira de Química Orgânica e Biológica. E. S. A. "Luiz de Queiroz" U. S. P. - Piracicaba

SUMMARY

The determination of total nitrogen, phosphorus, and potassium in plant material can be carried out in a common extract prepared with sulphuric acid and 30 per cent hydrogen peroxide.

Nitrogen is estimated by direct nesslerization of a suitable aliquot (1-5 ml of the 50 ml extract made out of 250 mg of dried material); in order to avoid excessive acidity, 10 ml of Nessler's reagent should be employed.

An aliquot of 1-5 ml suffices for the colorimetric determination of phosphorus by the molybdenum method; to reduce the phosphomolybdate complex 2 ml of a 2% SnC12 soln are necessary.

Potassium is determined by the cobaltinitrite method after elimination of ammonium salts with the aid of aqua-regia.

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AGRADECIMENTOS

Os autores agradecem : 1) Ao Prof. J. Mello Moraes pelas facilidades apresentadas em seu laboratório; 2) Ao Prof. R. A. Catani por sugestões apresentadas.

LITERATURA CITADA

DAMLE, S. P. and P. S. KRISHNAN, 1954 - One step digestion procedure for the estimation of total phosphorus and nitrogen in mould tissue. Anal. Chim. Acta. 11 (3): 225-228.