Selective extraction of zinc dithizonate in the presence of dithiocarbaminoacetic acid as masking agent Quantitative treatment of an extraction equilibrium

Dithiocarbaminoacetic acid (TCA) is proposed as an effective masking agent in the dithizone extraction determination of zinc in the presence of lead, cadmium and cobalt(II). The extraction equilibrium is treated quantitatively by means of two approaches: the "conditional distribution coefficient" and the computer program HAL-TAFALL. Both methods give similar results and enable the most suitable conditions for the separation and determination of zinc in the presence of the other ions to be determined. A successful attempt is made to predict the maximum permissible quantity of interfering elements. The experimental check, performed under various conditions, is in satisfactory agreement with the theory.