DEVELOPMENT OF AN EFFICIENT PROCEDURE FOR THE PRECONCENTRATION OF COPPER(II) AFTER SOLID PHASE EXTRACTION ON MODIFIED SAWDUST

A sensitive and selective preconcentration method has been developed for copper(II) using modified sawdust as an adsorbent. Sawdust was chemically modified with diethylenetriamine. Copper as CuCl42- was retained by the adsorbent in the column, eluted by nitric acid and subsequently determined by flame atomic absorption spectrometer. The effect of pH, chloride concentration, volume of the sample and diverse ions on the recovery of the analyte was investigated. A preconcentration factor of 250 was achieved using optimum conditions. The calibration graph was linear in the range 1-150 ng mL(-1) copper in the initial solution. The detection limit (3S(b)) was 0.2 ng mL(-1) and the relative standard deviations were 2.7 and 1.2% for 5 and 50 ng mL(-1) respectively (n = 10). It was revealed that after ten cycles of adsorption and desorption, the adsorbent retained its promising adsorption ability. The method was successfully applied to the determination of copper(II) in different water samples. Obtained results showed that the developed method is relatively simple, accurate, sensitive and selective.