A new dispersive liquid-liquid microextraction method for preconcentration of copper from waters and cereal flours and determination by flame atomic absorption spectrometry

Abstract

A simple, rapid, sensitive, and inexpensive dispersive liquid-liquid microextraction method was developed for the determination of trace amounts of copper by flame atomic absorption spectrometry (FAAS). N,N'-bis-(2-hydroxy-5-bromobenzyl)-2-hydroxy-1,3-diiminopropane was used as the chelating ligand. Several analytical parameters affecting the microextraction efficiency such as, sample pH, volume of extraction solvent (carbon tetrachloride), concentrations of the chelating ligand and NaCl, and sample volume were investigated and optimized. The effect of the interfering ions on the recovery of copper was also examined. Under the optimum conditions, the detection limit (3 sigma) was 0.75 mu g L-1 for copper with a sample volume of 10 mL, and a preconcentration factor of 20 was achieved. The relative standard deviation (R. S. D) for ten independent determinations of a 10 mu g L-1 solution of Cu(II) was 2.3 %. In order to verify the accuracy of the developed method, different certified reference materials (SLRS-5, QCS-19, Rice flour unpolished high level of Cd NIES 10c) were analyzed and the results obtained were in good agreement with the certified values. The proposed method was applied to tap water, river water, seawater, rice flour, and wheat flour samples. The percentage recovery values for spiked water samples were between 95.4 and 108.4.