Specific recognition of cationic paraquat in environmental water and vegetable samples by molecularly imprinted stir-bar
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ORIGINAL PAPER
Specific recognition of cationic paraquat in environmental water and vegetable samples by molecularly imprinted stir-bar sorptive extraction based on monohydroxylcucurbit[7]uril–paraquat inclusion complex Jianmei Yao 1 & Lingxue Zhang 1 & Jinfeng Ran 1 & Shasha Wang 1 & Nan Dong 1,2 Received: 27 March 2020 / Accepted: 17 August 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Molecularly imprinted stir-bar coatings were created based on a hydroxylcucurbit[7]uril–paraquat inclusion complex. The inclusion complex that contained paraquat (PQ) as a template and monohydroxylcucurbit[7]uril ((OH)Q[7]) as a monomer was preassembled mainly through cavity inclusion interaction of (OH)Q[7] to form a one-dimensional self-assembly structure. The inclusion complex was anchored chemically on the surface of a glass stir bar with hydroxy-terminated poly(dimethylsiloxane) by the sol–gel technique to obtain a molecularly imprinted polymer-coated stir bar (MIP-SB). The molecularly imprinted coating showed specific adsorption for cationic PQ in aqueous media. Other quaternary amine compounds with a similar structure that coexisted in the solution, such as ethyl-viologen, diquat, and difenzoquat, were almost not extracted by the prepared MIP-SB. The sorptive capacity of the MIP-SB for PQ was nearly four times that of the non-imprinted stir bar (NIP-SB). The recognition mechanism indicated that the selectivity and extraction capacity resulted mainly from the imprinted cavity in the polymer that was formed by a one-dimensional assembly structure consisting of the (OH)Q[7]–PQ inclusion complex. The imprinted cavity was complementary to the PQ in shape, size, and functionality. A method to determine PQ in environmental water and vegetable samples was developed by combining MIP-SB sorptive extraction with HPLC-UV. The linear range was from 100 to 10,000 ng L−1 with a 8.2 ng L−1 detection limit for water samples and 0.02–0.85 mg kg−1 with a 0.005 mg kg−1 detection limit for vegetable samples. The limit of detection for both samples was lower than the EU-established maximum residual levels and that of other previously reported methods. The average recoveries were 70.0–96.1% with a relative standard deviation ≤ 7.6%, which showed the successful application in real sample analysis. Keywords Cucurbit[7]uril . Imprinted polymer coating . One-dimensional self-assembly . Vegetable samples
Introduction Paraquat (PQ), 1,1-dimethy-4,4-bipyridine dichloride, is a herbicide that has been used extensively in agriculture for decades. PQ has a high solubility in water; enters the Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-020-04491-5) contains supplementary material, which is available to authorized users. * Nan Dong [email protected] 1
School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
2
Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guiyang 550025, China
environment easily to affect
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