Determination of nickel(II) and cobalt(II) in an aqueous solution using 4-(2-Pyridylazo)-resorcinol/Capriquat-loaded silica gel.

Abstract

The separation and preconcentration of trace nickel(II) and cobalt(II) form an aqueous solution for a graphite-furnace atomic-absorption spectrometric (GF-AAS) determination was studied using silica gel loaded with 4-(2-Pyridylazo)-resorcinol (PAR)/trioctylmethylammonium chloride (Capriquat). The proposed adsorbent was prepared as follows: ten grams of silica gel were shaken into 25 ml of a 5% Capriquat-xylen solution and a 0.01% PAR solution for 30 minutes. A sample solution of 1001000 ml containing Ni(II) and Co(II) was adjusted to pH 9.0. The solution was then passed through 1.0 g of PAR/Capriquat-loaded in a silica gel column at a flow rate of 10 ml min-1. The Ni(II) and Co(II) collected on the PAR/ Capriquat-loaded silica gel on the column was eluted with 10 ml of 0.2 M nitric acid, and then deteminated by GF-AAS. In this method, over 99% of the Ni (II) and Co(II) was adsorbed at about pH 9.0. The calibration curve was linear from 0.05 to 2.5 μg/1 Ni(II) and 0.03 to 3.0 μg/l Co(II). The proposed method has been applied to the determination of Ni(II) and Co(II) in sea-water samples.