Determinação polarografica do zinco em plantas, após a sua separação em resina trocadora de íons

Catani, R. A.; Gloria, N. A. da; Bergamin Filho, H.

doi:10.1590/S0071-12761962000100008

Resumos

O presente trabalho relata os dados obtidos na determinaçao do zinco em plantas segundo uma nova técnica. Esta nova técnica consistiu em se aliar a separação do zinco de outros interferentes, através do emprego de uma coluna de resina trocadora de anions, ao método polarografico da dosagem do citado elemento. A amostra de planta (1, 000g) foi incinerada em copo de Pyrex a 450-5009C durante 90 minutos e o zinco foi extraido da cinza com solução de HC1 2N. A separação do zinco de outros elementos interferentes foi feita pela passagem da solução através da resina trocadora de anions, Amberlite, IRA-401. Após a eluiçao do zinco da coluna, a solução obtida foi levada ao polarografo registrador. (Sargent, modelo XXI) para a determinação, Trabalhando-se com um conjunto de 10 (dez) a 12 (doze) colunas de resina, pode-se executar 10 (dez) a 12 (doze) determinações num periodo de 6 (seis) horas.

This paper deals with the polarographic determination of zinc in plants after its separation with an anion exchange resin column. One gram of plant was ashed in a 20 ml beaker at 4505009C for 90-100 minutes. The solution of plant ash in 2N hydrochloric acid was passed through the column formed by a resin bed (Amerlite IRA-401) of 9 cm of length, which adsorbed zinc in the form of an anion an allowed to pass all the interfering ions. Twenty ml of 0,125 N sodium nitrate solution was used to elute the zinc and the effluent was dried in silica dish in vapour bath. Ten ml of 0, 35 N ammonium hydroxide with 0, 0125 % of gelatin, were added to the dish and the solution was stirred in order to dissolve the zinc. Three to five ml of solution were transferred to one special cell of the Sargent Visible Recording Polarograph Model XXI and the polarogram were obtained with the dropping mercury electrode and the stationary pool of mercury as the second electrode. Some of the obtained data are presented: PLANT Micrograms of zinc Micrograms %Recuperation added to the sample of zinc found (average) Coffee (leaves) 0,0 9,2 Coffee (leaves) 0,0 9,2 Coffee (leaves) 0,0 9,2 Coffee (leaves) 20,0 29,2 Coffee (leaves) 20,0 30,4 101,4 Coffee (leaves) 20,0 29,2 Sweet Clover (aerial part) 0,0 22,4 Sweet Clover (aerial part) 0,0 22,4 Sweet Clover (aerial part) 0,0 21,2 Sweet Clover (aerial part) 20,0 42,4 Sweet Clover (aerial part) 20,0 43,6 101,9 Sweet Clover (aerial part) 20,0 42,4 Sugar Cane (leaves) 0,0 12,0 Sugar Cane (leaves) 0,0 12,0 Sugar Cane (leaves) 0,0 10,8 Sugar Cane (leaves) 20,0 31,8 Sugar Cane (leaves) 20,0 31,8 100,6 Sugar Cane (leaves) 20,0 31,8 With the proposed method it is possible to analyse ten to twelve plant samples in six hours.

E. S. A. "Luiz de Queiroz"

RESUMO

O presente trabalho relata os dados obtidos na determinaçao do zinco em plantas segundo uma nova técnica. Esta nova tecnica consistiu em se aliar a separação do zinco de outros interferentes, através do emprego de uma coluna de resina trocadora de anions, ao método polarografico da dosagem do citado elemento.

A amostra de planta (1, 000g) foi incinerada em copo de Pyrex a 450-5009C durante 90 minutos e o zinco foi extraido da cinza com solução de HC1 2N. A separação do zinco de outros elementos interferentes foi feita pela passagem da solução através da resina trocadora de anions, Amberlite, IRA-401. Após a eluiçao do zinco da coluna, a solução obtida foi levada ao polarografo registrador. (Sargent, modelo XXI) para a determinação, Trabalhando-se com um conjunto de 10 (dez) a 12 (doze) colunas de resina, pode-se executar 10 (dez) a 12 (doze) determinações num periodo de 6 (seis) horas.

SUMMARY

This paper deals with the polarographic determination of zinc in plants after its separation with an anion exchange resin column.

One gram of plant was ashed in a 20 ml beaker at 4505009C for 90-100 minutes. The solution of plant ash in 2N hydrochloric acid was passed through the column formed by a resin bed (Amerlite IRA-401) of 9 cm of length, which adsorbed zinc in the form of an anion an allowed to pass all the interfering ions. Twenty ml of 0,125 N sodium nitrate solution was used to elute the zinc and the effluent was dried in silica dish in vapour bath. Ten ml of 0, 35 N ammonium hydroxide with 0, 0125 % of gelatin, were added to the dish and the solution was stirred in order to dissolve the zinc. Three to five ml of solution were transferred to one special cell of the Sargent Visible Recording Polarograph Model XXI and the polarogram were obtained with the dropping mercury electrode and the stationary pool of mercury as the second electrode.

Some of the obtained data are presented:

PLANT Micrograms of zinc Micrograms %Recuperation

added to the sample of zinc found (average)

Coffee (leaves) 0,0 9,2

Coffee (leaves) 20,0 29,2

Coffee (leaves) 20,0 30,4 101,4

Coffee (leaves) 20,0 29,2

Sweet Clover (aerial part) 0,0 22,4

Sweet Clover (aerial part) 0,0 21,2

Sweet Clover (aerial part) 20,0 42,4

Sweet Clover (aerial part) 20,0 43,6 101,9

Sweet Clover (aerial part) 20,0 42,4

Sugar Cane (leaves) 0,0 12,0

Sugar Cane (leaves) 0,0 10,8

Sugar Cane (leaves) 20,0 31,8

Sugar Cane (leaves) 20,0 31,8 100,6

Sugar Cane (leaves) 20,0 31,8

With the proposed method it is possible to analyse ten to twelve plant samples in six hours.

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Recebido para publicação em 18/6/62.

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