Alumina coated with oxazolone derivative for extraction of trace amounts of cadmium and copper from water and plant samples

A solid phase extraction procedure is proposed for simultaneous separation and preconcentration trace amounts of Cu(II) and Cd(II) using alumina coated with N′-{4-[4-{1-[4-(dimethylamino)phenyl]methylidene}-5-(4-H)oxazolone]phenyle}acetamide and determination by flame atomic absorption spectrometry. Using 0.1 g of the sorbent, the metal ions were sorbed at pH 7 and recovered with 5.0 mL of 0.5 mol L−1 HNO3. It was found that extraction can be performed from the sample volumes of 2000 and 800 mL for Cu and Cd, respectively (preconcentration factors of 400 for Cu and 160 for Cd). Obtained sorption capacities for 1 g sorbent were 8 mg Cu and 14 mg Cd. The linearity was maintained in the concentration range of 0.1 ng mL−1 to 7.0 μg mL−1 for Cu and 0.13 ng mL−1 to 2.0 μg mL−1 for Cd in the original solution. Eight replicate determinations of a mixture containing 1.0 μg mL−1 each of the elements in the final solution gave relative standard deviation ±1.6 and ±1.3% for Cu and Cd, respectively. The detection limit was calculated as 0.06 and 0.05 ng mL−1 for Cu and Cd, respectively. The proposed method was successfully applied to the determination trace amounts of Cu and Cd in the water and plant samples.