Zhigang Xu

Barbell-shaped stir bar sorptive extraction using dummy template molecularly imprinted polymer coatings for analysis of bisphenol A in water

This study reports the development of a novel dummy template molecularly imprinted polymer (MIP)-coated barbell-shaped stir bar. The MIP stir bar coatings were prepared by using 2,2-bis(4-hydroxyphenyl)butane (BPB), 4,4-dihydroxydiphenylmethane (BPF), 4-tert-butylphenol (PTBP), and tetrabromobisphenol A (TBBA) as dummy templates using a capillary in situ polymerization method. Uniform coatings can be prepared controllably. The method is simple, easy, and reproducible. The barbell-shaped stir bar was developed by using medical silicone tubes as wheels. The wheels could be removed and reinstalled when necessary; therefore, the barbell-shaped stir bar was easy to disassemble and reassemble. The novel MIP-coated stir bar showed good selectivity for the target analyte, bisphenol A (BPA). The established method is selective and sensitive with a lower detection limit for BPA of 0.003xa0μg/L. The dummy template MIP-coated stir bar is suitable for trace BPA analysis in real environmental water samples without template leakage. The novel stir bar can be used at least 100 times.

β-Cyclodextrin molecularly imprinted solid-phase microextraction coatings for selective recognition of polychlorophenols in water samples

AbstractA series of β-cyclodextrin derivatives were designed and synthesized. The derivatives were investigated as functional monomers in molecularly imprinted polymeric solid-phase microextraction (MIP-SPME) fiber coatings. The coatings, with a layer thickness of 250 μm, were immobilized onto stainless steel using a capillary tube as a mold. This study employed a simple, easy, and reproducible method to prepare uniform coatings for polychlorophenols extraction. The combination of molecular inclusion effects and the molecular imprinting sites was expected to enhance the molecular recognition ability for polychlorophenols. Compared with non-imprinted polymer coatings and MIP coatings with methacrylic acid as the functional monomer, the β-cyclodextrin MIP-SPME coatings exhibited significantly higher extraction amounts and excellent selectivity to the template of triclosan. The MIP-SPME coatings exhibited a favorable synergistic extraction capacity resulting from the β-cyclodextrin cavity and molecularly imprinted binding sites. The method of β-cyclodextrin MIP-SPME coupled with high performance liquid chromatography (HPLC) for triclosan and polychlorophenols analysis in real water samples was developed. The limit of quantification was 1 μg/L for the three polychlorophenols. The recovery for three analytes ranged from 83.71% to 109.98%, with the relative standard deviation (RSD) of 2.83% to 12.19%. The β-cyclodextrin MIP-SPME fiber coatings could be used for at least 100 cycles.n Graphical AbstractSynergistic effects in β-cyclodextrin MIP-SPME

Mixed-Template Molecularly Imprinted Technique and its Application Research

Molecularly imprinted techniques have been rapidly developed in recent decade. Some novel molecularly imprinted techniques and some novel application forms of molecularly imprinted polymers have been developed. And it has been widely used in sample pretreatment. In this paper, novel mixed-template molecularly imprinted techniques are introduced. The development and applications of mixed-template molecularly imprinted techniques in recent decade are reviewed, including dual-template molecularly imprinted technique and multi-template molecularly imprinted technique, and its application in chromatographic solid phase, solid phase extraction and microsphere extraction. Moreover, the trends of mixed-template molecularly imprinted techniques in sample pretreatment are prospected.

Molecularly Imprinted Polymers for the Analysis of Environmental Estrogen Bisphenol A

Molecularly imprinted polymer (MIP) has the characteristics of predetermination, specific recognition and practicability. It can eliminate the interference of complicated matrix. It has been widely used as selective adsorption material in sample preparation. Bisphenol A is a common endocrine disruptor in environment. Its toxic effects and analysis have attracted widespread concern. In this paper, the molecularly imprinted sample preparation techniques for bisphenol A were comprehensively reported, including molecularly imprinted microspheres extraction, molecularly imprinted solid phase extraction, molecularly imprinted solid phase microextraction, molecularly imprinted stir bar sorptive extraction and molecularly imprinted membrane extraction. Moreover, the trends of BPA-molecularly imprinted techniques are prospected.