Preconcentration and determination of lead(II) by microextraction based on suspended cadion covered zirconia nanoparticles in a surfactant media

We have developed a method for the microextraction of lead(II) ion. It is based on the use of suspended zirconia nanoparticles modified with the reagent cadion. Pb(II) ions in the sample are adsorbed onto the modified zirconia nanoparticles suspended in the solution of a non-ionic surfactant. After cloud formation and phase separation by sedimentation, the surfactant rich phase was acidified and diluted to 100 mu L with 3.0 mol L-1 nitric acid and ultrasonicated for a few seconds to desorb the analyte from the sorbent. The mixture was centrifuged and 10 mu L of the supernatant liquid phase along with 10 mu L of the Pd/Mg modifier were submitted to the electrothermal atomic absorption spectrometer. The parameters affecting the extraction efficiency were optimized by the univariable method. Under the optimized conditions, a sample volume of 40 mL resulted in an enhancement factor of 384 and a detection limit (defined as 3S(b)/m) of 2.2 ng L-1. The method was successfully applied to the determination of Pb(II) in water, tea and rice samples. Accuracy was determined by the recovery experiments and the analysis of two certified reference materials.