Rapid determination of zinc in seawater by column preconcentration/AAS

Abstract

Atomic absorption spectrometry with on-line chelating-resin column preconcentration has been applied to rapid determination of zinc in seawater. Filtered coastal seawater samples adjusted to pH 2.2 by adding 1 ml of conc. nitric acid against to 1 l of seawater was pumped at 6.0 ml min^-1 and mixed with a stream of ammonium acetate buffer (pH 7) at 0.5 ml min^-1. The sample was then passed through a microcolumn (3.2 mm i.d. 16 mm long) packed with Chelex-100 for 1 min. The column was washed with distilled water for 30 s and sequentially chelated zinc was eluted with about 160 μl of 2 M nitric acid at 3.0 ml min^-1 for AAS determination. This method gave enhanced sensitivityof zinc by over 19 times better than that of a conventional AAS. The detection limit of the present method was 0.5 ppb (S/N=2). Precision of this method was 2.7% (R.S.D.) at the 10 ppb level of zinc aqueous standard. About 30 samples could be analyzed for 1 h. The present method was successfully applied to the rapid determination of zinc in seawater of Beppu Bay.