Ultratrace determination of lead, cadmium and copper in environmental and biological samples by atomic absorption spectrometry after their separation and preconcentration using octadecyl silica membrane disks modified with a new N-S Schiff base

Pb(II), Cd(II) and Cu(II) ions were separated and preconcentrated by solid-phase extraction on octadecyl-bonded silica membrane disks modified with a new S-N-containing Schiff base ( bis -2-thiophenal propandiamine) (BTPD) followed by elution and atomic absorption spectrometric detection. The method was applied as a separation and detection method for lead(II), cadmium(II) and copper(II) in environmental and biological samples. Extraction efficiency and the influence of sample matrix, flow rate, pH, and type and minimum amount of stripping acid were investigated. The maximum capacity of the membrane disks modified by 4 mg of BTPD was found to be 668 +/- 10, 480 +/- 8 and 454 +/- 7 mug of lead, cadmium and copper, respectively. The limit of detection of the proposed method is 0.25, 0.01 and 0.02 ng/mL for lead, cadmium and copper, respectively.