DETERMINATION OF Cr(III), Fe(III), Ni(II), Pb(II) AND Zn(II) IONS BY FAAS IN ENVIRONMENTAL SAMPLES AFTER SEPARATION AND PRECONCENTRATION BY SOLVENT EXTRACTION USING A TRIKETONE REAGENT

A simple, rapid and accurate method was developed and evaluated for the separation and preconcentration of trace levels of Cr(III), Fe(III), Ni(II), Pb(II) and Zn(II) ions in environmental samples, prior to their determinations by flame atomic absorption spectrometry (FAAS). Ethyl 2-(4-methoxybenzoyl)-3-(4-methoxyphenyl)-3-oxopropanoylcarbamate (EMPC) was used as a complexing agent. Effects of some analytical parameters on the extraction yield of the metal ions, such as pH of the aqueous phase, amount of the EMPC reagent, volume of MIBK, effect of ionic strength, back extractant type, sample volume, and foreign ions etc. were investigated. No interferences were observed due to major components and some metal ions in the samples. The limits of detection (LOD) were found in the range 0.3-0.7 mu g L-1. The recoveries were found to be higher than 95%, and the relative standard deviations (RSD) predicted less than 4% (n = 8). The accuracy of the method was checked by analyses of a certified reference material and spiked samples. The developed method was applied to several matrices, such as water and food samples