A separation method to overcome the interference of aluminium on zinc determination by inductively coupled plasma atomic emission spectroscopy

The use of polyurethane foam (PUF) to separate zinc from large amounts of aluminium and its determination by inductively coupled plasma atomic emission spectroscopy technique (ICP-AES) in aluminium matrices is described. The proposed method is based on the solid-phase extraction of the zinc(II) cation as a thiocyanate complex. Parameters such as effect of pH on zinc sorption, zinc desorption from the foam and analytical features of the procedure were studied. Results showed that the zinc(II) cation within the range from 0.02 to 65.0 mu g in 0.2 mol l(-1) thiocyanate solution and pH range from 1.0 to 4.0, could be quantitatively extracted by 0.1 g of PUF. The precision of the method was calculated as the relative standard deviation from a series of seven measurements. It was 3.9% for 1.0 mu g of zinc in a volume solution of 50 ml. The proposed procedure was used for zinc determination in both aluminium alloys and salts with zinc concentration in the range from 50 to 300 mu g g(-1). A standard addition technique was used and achieved results showing that this procedure has good accuracy and precision. (C) 2000 Elsevier Science B.V. All rights reserved.