Ultrasonic-Assisted Micro Solid Phase Extraction of Arsenic on a New Ion-Imprinted Polymer Synthesized from Chitosan-Stabilized Pickering Emulsion in Water, Rice and Vegetable Samples
Pickering emulsion polymerization has been employed for the Ultrasonic assisted-micro solid phase extraction (UA-µSPE) of ultra trace arsenic species by a new magnetic ion imprinted polymer (MIIP) prior to hydride generation atomic absorption spectrometry. Hydride generation atomic absorption spectrometry (HGAAS) has been used due to its fast analysis time, simplicity, acceptable selectivity and inexpensive cost. 2-acetyl benzofuran thiosemicarbazone (2-ABT) as a new chelating agent and core- shell hydrophobic magnetic nanoparticles was synthesized and the polymerization was carried out at the presence of arsenic - ligand complex, crosslinker, monomer, initiator, stabilizing agent and water-oil emulsion magnetic carrier. The polymerization of IIP is usually carried out by covalent or non-covalent interactions between functional monomer and targeted template ion. The use of ultrasonic waves in polymerization process due to the cavitation effect and acoustic shock through physical phenomena such as micro-streaming and micro-turbulence can lead to dramatic increase in mass transfer, faster start-up and operative mixing and micro-mixing. Therefore, an improvement in the preconcentration efficiency of the method by decreasing the external and internal resistance of the mass transfer of the analyte is achieved. Introducing of magnetism to nano-adsorbents can provides a relatively rapid and easy procedure to separate them from aqueous phase by employing appropriate magnetic field. In addition to eliminating the centrifuge stage, deposition of polymer on these nanoparticles leads to an increase in surface area and ease of access to active polymer sites which can significantly improve the kinetic of metal absorption. In pickering emulsion polymerization method, solid colloidal particles act as stabilizers between two immiscible phases to form an emulsion and it is used to prepare of controlled size and stable nano-absorbent. In order to stabilize pickering emulsion polymerization in MIIP formulation, suitable stabilizers should be used. Chitosan with some unique properties such as biocompatibility, biodegradability and non-toxicity can be a good candidate for this purpose. Furthermore this biopolymer adsorbs heavy metals by chemisorption because of its amino and hydroxyl functional groups. In second step, the nanoparticles and polymers were characterized. The analytical parameters such were selected and optimozed by Plackett–Burman and Box–Behnken designs respectively. Linear dynamic range, detection limit and relative standard deviation were 0.01-85.000 µg.L-l, 0.003 µg.L-l, and 3.21%, respectively. The proposed preconcentration procedure was successfully applied to the determination of arsenic ion in a wide range of food samples with different and complex matrixes.