A determinação do cobre pelo método calorimétrico do dietilditiocarbamato de sódio

A determinação do cobre pelo método calorimétrico do dietilditiocarbamato de sódio^*

A.O. Jacintho

Cadeira de Química Analítica e Físico-Química da ESALQ

RESUMO

O trabalho em aprêço, relata o estudo de diversos aspectos do método espectrofotométrico da determinação do cobre pelo dietilditiocarbamato de sódio.

Dentre os aspectos estudados, podem ser citados os seguintes:

a) Reativo: influência da concentração e sua conservação em função do tempo.

b) Influência da quantidade de EDTA.

c) Solventes: escolha do solvente, do comprimento de onda e do filtro.

d) Estabilidade do composto.

e) Estudo da amplitude, exatidão e precisão do método.

f) Aplicação do método, na determinação do cobre em plantas e solos.

SUMMARY

A study is made on several aspects of the spectrophotometric method for the determination of copper by sodium diethyldithiocarbamate (DDC-Na).

From this work could be observed that:

a) The ideal amount of reagent a 1% of (DDC-Na) aqueous solution, was 1 ml and it was observed that the reagent keeps well until 40 days after its preparation.

b) The absorbancy of the copper diethyldithiocarbamate (DDC-Na) solutions, to a certain limit is independent of the amounts of EDTA Na₂. But, in the absence of EDTA-Na₂ the amounts of copper added where not recovered, when working with pure solutions.

c) Among the solvents used, carbon tetrachloride was considered the most appropriate.

d) DDC-Cu in CCl₄ shows maximum absorption in the wave lenght range 430-435 milimicrons. The greatest sensibility was obtained with filters numbers 42 and 44 (Klett-Summerson).

e) Interferences of the ions studied were eliminate, by the use of EDTA-Na₂ only.

f) In this procedure, the DDC-Cu is stable until 45 minutes.

g) The method obeys Beer's law in the range of 5-50 ppm, and shows good accuracy.

h) The recommended procedures for the determinations of total copper both in plants and soils by the DDC-Na, are considered efficients.

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LITERATURA CITADA

Entregue para publicação em 2/1/68.

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*

Resumo do trabalho apresentado pelo autor à E.S.A. "Luiz de Queiroz", como tese para obtenção do título de Doutor em Agronomia.

Datas de Publicação

• Publicação nesta coleção
  13 Jun 2012
• Data do Fascículo
  1967