Application of modified nano-alumina as a solid phase extraction sorbent for the preconcentration of Cd and Pb in water and herbal samples prior to flame atomic absorption spectrometry determination

摘要

The first study on the high efficiency of nanometer-sized γ-alumina coated with sodium dodecyl sulfate-1-(2-pyridylazo)-2-naphthol (SDS-PAN) as a new sorbent solid phase extraction (SPE) has been reported. A microcolumn packed with modified nanometer-sized alumina was used to preconcentrate and separate Cd and Pb in water and herbal samples. The metals were eluted with 2 mL HNO_3 directly and detected with the detection system flame atomic absorption spectrometry (FAAS). Various influencing parameters on the separation and preconcentration of trace metals, such as pH, flow rate, sample volume, amount of sorbent, and concentration of eluent, were studied. Under the optimized operating conditions, the sorption capacities of the modified nano-γ-alumina for Cd and Pb were 11.1 and 16.4 mg g~(-1) respectively. With 500.0 mL sample an enrichment factor of 250 was obtained. The detection limits of this method for Cd and Pb were 0.15 and 0.17 μg L~(-1) and the R.S.D.S were 2.8 and 3.2% (n =10), respectively. The proposed method has been applied to the determination of these metal ions at trace levels in certified reference materials and real samples with satisfactory results.