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چکیده
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Molecular imprinting is a technique that creates recognition sites by polymerization of functional monomers and cross linkers in the presence of the template molecule. Molecularly imprinted polymer (MIP) employed as solid-phase microextraction (SPME) coating for effective and selective separation of template [1]. Natural compounds, like tragacanth gum (TG), due to unique physical, chemical and biological properties such as non-toxicity, biocompatibility, eco-friendliness and stability over wide pH ranges, have been find a lot of application in recent years [2]. In this study the TG molecule, due to presence of plenty hydroxyl and carboxylic acid groups was employed as crosslinking agent to create a novel MIP-SPME fiber for extraction of chrysophanol. To improve fiber stability and lifespan, a surface modified stainless steel wire (SSW), was used as supporting material. Polydopamine was used to covalently functionalize SSW, then the MIP was prepared by radical polymerization using chrysophanol as a template, vinyl imidazole (VI) as a functional monomer and TG as a crosslinking agent. The fiber was characterized by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR). Additional properties of fiber were also studied by complementary tests such as adsorption and extraction capacity experiments. Also, the extraction conditions, including pH, extraction time, desorption time, and desorption solvent were optimized. Finally, the efficiency of the fiber was evaluated with high-performance liquid chromatography with ultraviolet detector (HPLC-UV) for determination of chrysophanol in a urine sample. It was found that the mechanism of adsorption follows the Langmuir model, with the maximum capacity of 178.57 ng. In comparison to non-imprinted polymer coating, the MIPSPME coating exhibited significantly higher extraction amounts and excellent selectivity to the chrysophanol. The limit of quantification was 8.95 ng mL-1 . The recovery for the spiked sample ranged from 94.01% to 96.20%, with the relative standard deviation (RSD) of 4.30% to 5.06% for single fiber and between fibers, respectively.
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