Application of Ion-Imprinted Polymer Nanoparticles for Selective Trace Determination of Palladium Ions in Food and Environmental Samples with the Aid of Experimental Design Methodology Ebrahim Ghorbani-Kalhor & Mohammad Behbahani & Jafar Abolhasani Received: 16 October 2014 /Accepted: 1 December 2014 # Springer Science+Business Media New York 2014 Abstract A solid phase extraction method using Pd 2+ ion- imprinted polymer (Pd 2+ -IIP) nanoparticles combined with flame atomic absorption spectrophotometry (FAAS) was de- veloped for the preconcentration and trace detection of palladi- um ions. The Pd 2+ -IIP nanoparticles were obtained by precip- itation polymerization of 4-vinylpyridine (the functional mono- mer), ethylene glycol dimethacrylate (the cross-linker), 2,2′- azobisisobutyronitrile (the initiator), Eriochrome Cyanine R (the lead-binding ligand), and palladium ions (the template ion) in acetonitrile solution. The parameters affecting adsorp- tion and desorption steps were optimized by a Box–Behnken design through response surface methodology. Three variables (pH value, extraction time, and amount of the synthesized IIP) were selected as the main factors affecting sorption step, while four variables (type of eluent, volume of the eluent, concentra- tion of the eluent, and elution time) were selected for desorption step in the optimization study. The optimized values by this optimization method were 30 mg, 15 min, 6.0, HCl, 4.0 mL, 1.8 mol L -l HCl, and 14 min, for amount of polymer, retention time, pH of solution, type, volume, concentration of the eluent, and elution time, respectively. Under the optimized conditions, the detection limit for the proposed method was found to be 0.2 μgL -1 , while the relative standard deviation (RSD) for five replicate measurements was calculated to be <3 %. Finally, the introduced solid phase extraction technique was successfully applied for extraction and determination of Pd 2+ ions in food and environmental samples. Keywords Palladium ions . Ion-imprinted polymer nanoparticles . Food and environmental samples . Response surface methodology . Flame atomic absorption spectrophotometry Introduction Palladium is an element with increasing demands in today’ s industries. In 2007, an amount of 192 t of palladium has been sold in the world market. The main demands are automotive catalyst (55 %), electronics (17 %), jewelry (11 %), and dentistry (9 %) (Banham 2008), especially due to the catalytic properties it is widely used in the synthesis of many materials. Unfortunately, elevated level of palladium compared to geo- chemical background (Helmers et al. 1998) has been found in airborne particulate matter (Tilch et al. 2000), road dust (Boch et al. 2002), soil (Behbahani et al. 2014a), and grass (Ely et al. 2001). Anthropogenic palladium has been reported to be mobile and bioaccumulated by aquatic organisms and gener- ally to a larger extent than other platinum group elements (Van de Velde et al. 2000; Sures et al. 2001). Moreover, metallic palladium has an allergenic potential on humans (Van Ketel and Ntebber 1981). Therefore, monitoring of palladium in environmental samples has great importance with respect to estimation of the future risk of the human health and the ecosystem. The toxicity of palladium demands for practical techniques to remove it from the environment. In addition, because of the high economic value of palladium, its separa- tion even in trace amounts is beneficial. Some of the valuable techniques including ET-AAS (Zheng et al. 2007), ICP-AES flame atomic absorption spectrometry (FAAS) (Behbahani et al. 2014b; Bagheri et al. 2012a), ICP-MS (Krishna et al. 2009), and total reflection XRF spectrometry have been used for palladium determination. The abovementioned methods E. Ghorbani-Kalhor (*) : J. Abolhasani Department of Chemistry, Tabriz Branch, Islamic Azad University, Tabriz, Iran e-mail: ekalhor@iaut.ac.ir M. Behbahani Department of Chemistry, Shahid Beheshti University, G.C., Tehran 1983963113, Iran Food Anal. Methods DOI 10.1007/s12161-014-0057-7