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A simple and reliable method for the extraction and determination of trace amounts of copper(II) ions using activated carbon (AC) impregnated by a new Schiff base 5-[(4-heptyloxyphenyl)azo]-N-(4-propyloxyphenyl)-salicylaldimine (HPPS) and atomic absorption spectrometry is presented. Recovery efficiency and the influence of pH value, volume of sample solution, effect of different eluents, and interfering ions were evaluated. The limit of detection (3σ) was 2.62 ng•mL -1 and the relative standard deviation (n＝10) was 1.5%. Under optimum conditions, the copper ions were concentrated 25 fold using 250 mL of sample solution and 10 mL of eluent. This procedure has been successfully applied to the determination of copper in different water samples.

The extraction properties of cone-5, II,17,26,27,arene (1) in 1,2-dichloroethane towards rare-earth metal ions at 25°C have been investigated. The slope analysis showed a 1: I metal/ligand ratio for the extracted species (La, Eu, Er and Y). The distribution coefficients increase with the polarity of the diluents : chloroform < dichloromethane < 1,2-dichloroethane < nitrobenzene. In the competitive extraction of II rare-earth metal ions (La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb and Y), ligand 1 exhibits higher extraction efficiency and a better separation factor than tri-n-octylphosphine oxide.

A new procedure has been developed for chromium speciation in aqueous solution by the use of micellar, ion-association, solid-phase extraction techniques (SPE) followed by flame atomic absorption spectrometry. The method was based on the use of C-18 bonded phase silica SPE disks for retention of ion-associated Cr(VI) with cetyl trimethyl ammonium bromide (CTAB), elution of the retained species and subsequent detection by flame atomic absorption spectrometry (FAAS). Cr(III) was oxidized by potassium persulfate to Cr(VI), then the total chromium was retained on the disk and determined by FAAS. The amount of Cr(III) was calculated by the difference between the total and Cr(VI) values. The calculated limit of detections (LOD) (based on 3sigma) are 15 microg L(-1) and 20 microg L(-1) for Cr(VI) and Cr(III) respectively. No considerable interferences have been observed from other investigated anions and cations and the method has been successfully applied to water samples taken from the Karoon River in Khuzestan province.

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