Rapid determination of zinc in copper alloy by anion exchange separation-EDTA titration

Abstract

A simple and sensitive method was investigated for determination of zinc in copper alloy. The method is based on the combination of anion exchange separation by batch operation and EDTA titration. Sample is dissolved in 15 ml of HNO3(1+1) by heating, and resultant diluted to 200 ml with water. A 20 ml aliquot of this solution and 2 ml of H2SO4 (1+1) are taken into a beaker, and are evaporated to dryness. After cooling, the residue is dissolved in 2 N HCl by heating. The solution is transfered into the separatory funnel with a filter containing anion exchange resin Amberlite IRA-400, RCl form, (60~80)mesh. The separatory funnel is shaken for 4 minutes to adsorb zinc ion. The solution in the funnel is sucked off. Resin is washed by shaking for 20 seconds with 25 ml of 2 N HCl (containing 0.01% Pb) and this operation is repeated (5~7) times. The adsorbed zinc ion is eluted with 20 ml of 2 N NH4OH (containing 40 g/l NH4Cl) by shaking for 2 minutes, and the eluent is filtered into an Erlenmeyer flask with suction, and this operation is repeated 5 times. The eluted solution is diluted to 200 ml with water, and mixed with 2 ml of potassium cyanide solution (10%) and 3 ml of formaldehyde solution (2+8) to mask the other metal ions. The solution is titrated with 0.02 M EDTA solution by using EBT as indicator. The time required for this test was about half of a usual column method. © 1976, The Japan Society for Analytical Chemistry. All rights reserved.