Hybrid sorbent based on nano alumina – single walled carbon nanotube was applied to preconcentration of Pb(II), Cu(II) and Co(II) from various samples via solid phase extraction technique. The determination of Pb(II), Co(II) and Cu(II) ions was made by flame atomic absorption spectrometry (FAAS). Experimental parameters including pH of sample solution, sample volume, flow rate of sample solution, volume and concentration of eluent that affect the recovery of the analytes have been optimized. Under optimized experimental conditions, analytical parameters including limit of detection, limit of quantification, linear working range, precision and accuracy have been determined. Interfering effects of matrix constituent on the recovery of the analytes were studied. The reusability and adsorption capacity of the new hybrid sorbent were also investigated. The hybrid sorbent was successfully applied for preconcentration of Pb(II), Cu(II) and Co(II) from various samples with recovery values of 101 %, 95 % and 98 %, respectively. The analytical limit of detection was found to be 2.1 μg L-1, 0.9 μg L-1 and 1.1 μg L-1 for Pb(II), Co(II) and Cu(II), respectively. The hybrid sorbent was stable up to 100 runs. Adsorption capacities of the hybrid sorbent were 101.2 mg g-1 for Pb, 76.3 mg g-1 for Co and 53.2 mg g-1 for Cu. The accuracy of the method was confirmed by analyzing certified materials (BCR 150 Skim milk powder, CMI 7003 Silty clay) and spiked real samples. The method has been applied for the determination of analytes in tap water, dam water, soil and tea leaves.
Keywords: Flame atomic absorption spectrometry, Preconcentration, Nano alumina, Carbon nanotube, Solid phase extraction, Trace metal, Limit of detection, Limit of quantification, Precision, Accuracy, Hybrid Nano Sorbent