Computational Design Of Rhodamine 6G Molecularyl Imprinted System And Preparation, Application Of Boron-doped Nano-adsorbent

Rhodamine 6G(Rh6G), a derivative of xanthene dyes, has been widely used as a colorant in textile and foodstuffs. The use of Rh6 G for food coloring has raised serious concerns for the chronic toxicity,carcinogenicity, reproductive and developmental toxicity towards humans and animals, and then has been banned in food stuff by many countries.However, due to its low cost and high effectiveness, this harmful dye is still used by unethical manufacturers and will probably continue to be used in food coloring in some parts of the world. Therefore, the researches on the detection method of Rh6 G has been paid close attention.Due to multi-components of food samples, low content of the food additives, and serious interference of the background, development of highly sensitive and selective methods, such as micro solid-phase extraction using molecularly imprinted nano-adsorbent combined with the common analytical methods to detect Rh6 G, is of great significancefor human's food safety and environmental monitoring.In this paper, on the bases of computational design of molecularly imprinted system and optimizing selection of the suitable functional monomers for Rh6 G, an OA9(34) orthogonal array design was utilized to optimize the dosages of the monomers and the template, and a novel core–shell magnetic nano-adsorbent with surface molecularly imprinted polymer(MIP) coating for specific extraction of Rh6 G was prepared. The nano-adsorbent was then applied to dispersive micro solid-phase extraction(DMSPE) coupled with high-performance liquid chromatography(HPLC) for trace determination of Rh6 G in food, water and other related samples.(1) The molecularly imprinted system of Rh6 G was studied by density functional theory(DFT). The conformational optimizations and binding energies for the complexes of Rh6G-monomers were calculated by DFT method at B3LYP/6–31+G level with Gaussian 09 software. The results show that the complex formed among Rh6 G, dopamine(DA) and m-aminophenylboronic(APBA) with the mole ratio of 1:2:1 has highest stability compared with the corresponding Rh6G-p-phenylenediamine complex and Rh6G-aniline complex.(2) A novel core–shell magnetic nano-adsorbent with MIP coating was fabricated and then applied to DMSPE followed by determination of Rh6 G using HPLC. The MIP coating was prepared by copolymerizationof DA and APBA, both acting as functional monomers and cross-linkers,in the presence of Rh6 G, acting as template. The selection of the suitable functional monomers was based on the interaction between different monomers and the template using the density functional theory. The ratios of the monomers to template were further optimized by an OA9(34)orthogonal array design. The binding performances of the adsorbent were evaluated by static, kinetic and selective adsorption experiments. The results reveal that the as-developed adsorbent possesses remarkable affinity and binding specificity for Rh6 G because of the enhanced Lewis acid-base interaction between the B(?) embedded in the imprinted cavities and the template. The nano-adsorbent was successfully applied to DMSPE coupled with HPLC for trace determination of Rh6 G in real samples with a detection limit of 2.7 nmol L-1. Spiked recoveries ranged from 93.0 to 99.1%, 89.5 to 92.7%, and 86.9 to 105% in river water,matrimony vine and paprika samples, respectively, with relative standard deviations of less than 4.3%.