Optimization of Solid-phase microextraction for determination of lead in high-salt content sample by furnace Atomic Absorption spectroscopy (FAAS )

This work presents a novelty method investigated in pre-concentration of lead ion and matrix effect eliminate in high salinity medium using solid phase microextraction by furnace Atomic Absorption spectroscopy (FAAS ). Graphene@Fe3O4 was used as the sorbent and HNO3 1M was selected as the extraction solvent. Parameters such as: pH, amount of sorbent, time of adsorption and, time of desorption and stirring rate affecting on the extraction efficiency of method has been studied and optimized utilizing two decent optimization methods; factorial design and central composite design (CCD). In the present study, we synthesized Magnetic graphene@Fe3O4 nanosheets as adsorbent for the extraction, pre-concentration, and determination of trace amounts of lead. In spite of great improvements in sensitivity and selectivity of modern analytical methods, the direct determination of these elements in real samples is a difficult task. The main reasons come from the complexity of the matrix and low concentration of analytes in some samples, which are often below the detection limits of available techniques. Thus, the use of separation techniques to overcome matrix interference or enhance sensitivity through pre-concentration of the analyte is required. Fernandez and Manning, Ediger [1-3] found that the presence of NaCl reduced the apparent lead found. If NaCl is a major matrix material, it will produce a large background signal unless it is driven off in the ashing cycle. However, many analyte metals are lost at temperatures lower than that which will drive off the NaCl. The limit of detection and limit of quantification were 4.4 ng L-1 and 14.8 ng L-1, respectively. The accuracy of the method was evaluated by analyzing spiked real sample. Good spiked recoveries over range 84 -102 % were obtained. Under the optimum conditions the calibration graph was linear over the range 5-50 ngL-1. The relative standard deviation was 1% for four repeated determinations at a concentration of 20 ng L-1.