ICP-OES determination of trace metal ions after preconcentration by 4-(8-hydroxy-5-quinolylazo)naphthalenesulfonic acid modified silica gel

A new method of determination of trace metal ions in water samples was developed based on the silica gel modified with 4-(8-hydroxy-5-quinolylazo)naphthalenesulfonic acid as a new solid-phase extractant and determinated by inductively coupled plasma optical emission spectrometry (ICP-OES). Experimental conditions for effective adsorption of trace levels of metal ions were studied in details. Quantitative extraction of trace amounts of Cu (II), Zn (II), Cd (II), Cr (III), and Ni (II) was obtained at the optimal pH value (pH 4). The time needed to extract each sample was less than 10 min by the batch methods. Complete elution of the adsorbed metal ions from the sorbent was carried out using 2.0 mL of 0.5 mol L-1 of HCl. Common electrolytes and metal ions did not interfere with the adsorption and determination of the analytes. The relative standard deviations (RSDs) of this method were lower than 5.0%. The developed method was successfully applied to separation and pre-concentration of trace metal ions from the certified reference material (GBW 08301, river sediment) and real samples with satisfied results. (c) 2008 Elsevier B.V. All rights reserved.