Carrier element-free coprecipitation (CEFC) method for separation and pre-concentration of some metal ions in natural water and soil samples

A simple, rapid and sensitive separation/pre-concentration procedure for Cd(II), Cr(III), Co(II), Cu(II), Fe(III), Pb(II) and Mn(II) ions in environmental samples has been established. The present procedure is based on a combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations of understudy trace metal ions. A cationic surfactant (N-cetyl N,N,N trimethyl ammonium bromide (CTAB)) as coprecipitant was used without adding any carrier element for coprecipitation of understudy ions. The optimum conditions for the coprecipitation process were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant. The pre-concentration factor was found to be 10. The detection limits corresponding to three times the standard deviation of the blank (N = 20) for Cd(II), Cr(III), Co(II), Cu(II), Fe(III), Pb(II) and Mn(II) ions were found as 0.61, 16.8, 12.7, 1.36, 2.08, 4.30 and 0.22 mu g L-1, respectively. The present procedure was successfully applied for separation and pre-concentration of investigated ions in several liquid environmental samples. In order to support the accuracy of the method, the certified reference materials (BCR 141 R calcareous loam soil and CRM025-050 soil) were analyzed. The experimental results are in good agreement with the certified values. (C) 2010 Elsevier Ltd. All rights reserved.