In this research, a novel and efficient quinoline thioacetamide functionalized magnetic graphene oxide composite (GO@Fe3O4@QTA) was synthesized and utilized for dispersive magnetic solid phase preconcentration of Cd(II) and Ni(II) ions in urine and various food samples. A number of diverse methods were employed for characterization of the new nanosorbent. The design of experiments approach and response surface methodology were applied to monitor and find the parameters that affect the extraction performance. After sorption and elution steps, the concentrations of target analytes were measured by employing FAAS. The highest extraction performance was achieved under the following experimental conditions: pH, 5.8; sorption time, 6.0 min; GO@Fe3O4@QTA amount, 17 mg; 2.4 mL 1.1 mol L-l HNO3 solution as the eluent and elution time, 13.0 min. The detection limit is 0.02 and 0.2 ng mL-1 for Cd(II), and Ni(II) ions, respectively. The accuracy of the new method was investigated by analyzing two certified reference materials (sea food mix, Seronorm LOT NO 2525 urine powder). The interfering study revealed that there are no interferences from commonly occurring ions on the extractability of target ions. Finally, the new method was satisfactorily employed for rapid extraction and determination of target ions in urine and various food samples.

Abstract
 1. Introduction
 2. Experimental
  2.1. Reagents and materials
  2.2. Instrumentation
  2.3. Preparation of standard and working solutions
  2.4. Synthesis of quinolinethioacetamide functionalized magnetic GO composite
  2.5. Extraction procedure
  2.6. Real sample pretreatment
  2.7. Experimental design methodology
 3. Results and Discussion
  3.1. Characterization studies
  3.2. Optimization of MSPE parameters
  3.3. Effect of potentially interfering species
  3.4. Effect of sample volume
  3.5. Maximum sorption capacity measurement
  3.6. Analytical performance of the MSPE method
  3.7. Method validation
  3.8. Analytical application of the method in real matrices
 4. Conclusions
 References

• Leila Naghibzadeh(Department of Chemistry, Central Tehran Branch, Islamic Azad University)
• Mahboobeh Manoochehri(Department of Chemistry, Central Tehran Branch, Islamic Azad University) Corresponding Author