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In this work, a molecularly imprinted sensor employing copper sulfide (CuS) as a novel signal probe was successfully developed for ultrasensitive and selective determination of sulfathiazole (STZ). The reduction signals of Cu 2+ produced in the process of electron transfer of CuS containing large amounts of Cu 2+ are easy to be captured, which provide high electrochemical signals. Moreover, gold nanoparticles@covalent organic framework with excellent conductivity was introduced on the electrode surface for signal amplification and facilitating electron transfer processes of CuS. Under optimized testing conditions, the proposed sensor offered a linear DPV response to STZ over a very wide concentration range (1.0 × 10 -4 to 1.0 × 10 -11 mol L -1 ), with a limit of detection of 4.3 × 10 -12 mol L -1 . Fodder and mutton samples spiked with STZ were analyzed using this sensor, and the satisfactory recoveries ranging from 83.0% to 107.2% were obtained. In addition, the proposed sensor was used to determine the concentration of STZ in chicken liver and pork liver, with quantification results being near identical to those determined by high-performance liquid chromatography., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Organophosphorus pesticides have been widely used in agricultural production. However, the wide use of organophosphate also results in pesticide residues on the plant, which are harmful to human health because of their potential mutagenic and carcinogenic properties. Therefore, it is vital to develop a sensitive and effective analysis method to control pesticide residues., Results: In this study, a novel molecularly imprinted capillary monolithic column was prepared using trichlorfon as the template molecule by combining non-hydrolytic sol-gel process with a molecular imprinting technique. The resulting material was characterized by scanning electron microscopy and Fourier transform infrared. Under capillary electrochromatography, the effects of voltage, pH, ACN content and concentration of buffer solution on the electro-osmotic flow (EOF) of imprinted capillary monolithic column were evaluated in detail. Using this prepared material as stationary phase for capillary electrochromatography, a novel method of molecularly imprinted capillary electrochromatography (MICEC) for the detection of trace trichlorfon residues in vegetables was developed. Under optimal conditions, appreciable sensitivity was achieved with a LOD (S/N = 3) of 92.5 µg kg(-1) and method quantitation limit (MQL) of 305.3 µg kg(-1), respectively. The linear ranges of the calibration graph were 0.1 µg L(-1) to 10 mg L(-1). The peak area precision (RSD) for five replicate extractions of 0.01 mg L(-1) trichlorfon standard aqueous solution was 4.5%. To evaluate the accuracy of this method, the blank cucumber and cauliflower samples spiked with trichlorfon were extracted and analyzed by this method with good recoveries, ranging from 80.2% to 95.8%. Moreover, this method was successfully applied to the quantitative detection of the trichlorfon residues in leek samples., Conclusion: With good properties of high sensitivity and simple pre-treatment, this MICEC method could provide a new tool for the rapid determination of trace trichlorfon residue in complex food samples., (© 2013 Society of Chemical Industry.)

How to determine trace multipesticide residues in fruits is an important problem. This paper reports a molecularly imprinted polymer (MIP) that was prepared using 4-(dimethoxyphosphorothioylamino)butanoic acid as the template, acrylamide as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. The novel imprinted polymer was characterized by static and kinetic adsorption experiments, and it exhibited good recognition ability and fast adsorption-desorption dynamicd toward trichlorfon, malathion, acephate, methamidophos, omethoate, dimethoate, phosphamidon, monocrotophos, and methyl parathion. Using this imprinted polymer as sorbent, matrix solid-phase dispersion coupled to gas chromatography for simultaneous determination of nine trace organophosphorus pesticide residues was first presented. Under the optimized conditions, the LOD (S/N = 3) of this method for the nine organophosphorus was 0.3-1.6 μg kg(-1); the RSD for three replicate extractions ranged from 1.2 to 4.8%. The apple and pear samples spiked with nine organophosphate pesticides at levels of 20 and 100 μg kg(-1) were determined according to this method with good recoveries ranging from 81 to 105%. Moreover, this developed method was successfully applied to the quantitative detection of the nine organophosphorus pesticide residues in orange samples.

How to determine the multipesticide residues in vegetables is an important problem. In this study, a new molecularly imprinted polymer was synthesized using O,O-dimethyl thiophosphoryl chloride, an intermediate for the manufacture of organophosphorous pesticides, as the template. Characterization test indicated that the synthesized polymer exhibited good recognition and selectivity for dichlorvos, methamidophos, acephate, folimat, monocrotophos, parathion-methyl, phosphamidon, and malathion. A molecularly imprinted SPE coupled to GC for simultaneous separation and determination of eight organophosphorous pesticides residues was developed. Under optimal conditions, the linear range of this method was 0.001-10.0 mg/L. The LOD of this method was in the range of 0.13-0.90 μg/kg. With a flow rate of 2.5 mL/min for loading 100 mL, the enrichment factor in the range of 25-480 for the eight organophosphorous pesticides was obtained. The RSD of the eight organophosphorous pesticides based on five replicates was from 1.50 to 4.09%. The accuracy of the proposed method was evaluated by recovery measurements on spiked samples, and good recovery rates ranging from 80.11 to 97.70% were achieved. Moreover, this method was evaluated for the quantitative detection of eight organophosphorous pesticide residues in leek and pakchoi samples., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Olaquindox, as one of the antimicrobial growth accelerants, is usually used in livestock production to improve feed efficiency. Due to health concerns over possible carcinogenic, mutagenic and photoallergenic effects of olaquindox on animals, the development of simple, rapid and sensitive analytical method for determination of olaquindox is crucial and necessary., Results: In this study, a surface molecularly imprinted polymer was prepared by a molecular imprinting technique in combination with a sol-gel process using activated silica gel as a support material. This imprinted material exhibited with good recognition and selective ability, and fast adsorption-desorption dynamics toward olaquindox. Using it as the recognition element, a new on-line molecularly imprinted solid phase extraction coupled with chemiluminescence sensor for the determination of olaquindox was developed. The factors affecting preconcentration of the analytes and sensitivity of the method were all investigated. Under the optimal condition, the linear range of the calibration graph was between 2 × 10(-8) and 1 × 10(-6) g mL(-1) , and the detection limit of this method was 7 × 10(-9) g mL(-1) . The blank chick feed samples spiked with olaquindox at 0.3, 0.9 and 1.5 µg g(-1) levels were extracted and determined by this presented method with recoveries ranging from 87% to 94%. This method was validated by high-performance liquid chromatography and the results correlated well with those obtained by both methods. Moreover, this method was quantitatively analysed with two contaminated chick feed samples., Conclusion: This study will provide a sensitive and fast method for the monitoring of olaquindox residues in foods., (Copyright © 2012 Society of Chemical Industry.)

Background: Olaquindox, one of the antimicrobial growth accelerants, is usually used as a feed additive in livestock production to improve feed efficiency. Due to health concerns over possible carcinogenic, mutagenic and photoallergenic effects of olaquindox on animals, the development of a simple, rapid and sensitive analytical method for determination of olaquindox is crucial and necessary., Results: In this paper, a novel and hydrophilic functionalised material of olaquindox-imprinted polymer was synthesised in aqueous solution by a surface molecular imprinting in combination with a sol-gel process. This imprinted material was characterised by Fourier transform infrared, scanning electron microscopy, and static and kinetic adsorption experiments, and results showed that it had good recognition and selective ability, and fast adsorption-desorption dynamics for olaquindox. Applying the prepared material as sorbent, a method of molecularly imprinted solid-phase extraction (MISPE) for separation and analysis of olaquindox residues in feeds coupled with HPLC was presented. Under the selected MISPE condition, the detection limit (S/N = 3) for olaquindox was 68.0 ng L(-1), the RSD for five replicate extractions of 50 µg L(-1) olaquindox was 9.8%. The blank chick feed samples spiked with olaquindox at 0.0025 and 0.010 mg g(-1) levels were extracted and determined by the developed method, with recoveries ranging from 90% to 96%., Conclusion: This method was applied for enrichment and analysis of olaquindox in animal feed samples with good accuracy and repeatability. This study will provide a sensitive and fast method for the monitoring of olaquindox residues in foods., (Copyright © 2011 Society of Chemical Industry.)

Abstract: In this study, a molecularly imprinted polymer (MIP)‐fluorescent probe based on hydrophobic CdSe/ZnS quantum dots (CdSe/ZnS@MIP) was designed and synthesized by bulk polymerization for detecting methamidophos (MAP). The CdSe/ZnS@MIP was characterized by Fourier‐transform infrared spectroscopy, thermo‐gravimetric analysis and adsorption properties, and it exhibited good adsorption capacity and fluorescent stability, and excellent selectivity. Under optimal conditions, the fluorescence showed a good linear decrease in the range of 3.50 × 10−7–0.71 × 10−3 mol/L with a correlation coefficient of 0.995. The limit of detection of the fluorescent probe was 9.16 × 10−8 mol/L, and the relative standard deviation of the method for nine replicate analyses of 4.0 × 10−6 mol/L MAP was 4.1%. Apple and pear samples spiked with MAP at three levels were extracted and determined by the presented method with good recoveries (89.7%–94.9%). The accuracy of the method was verified by gas chromatography for the detection of kidney beans, leek and cucumber samples, and no significant difference was observed for the results of two methods. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a new sensor of molecularly imprinted solid‐phase extraction coupled with flow‐injection chemiluminescence for the detection of monocrotophos was fabricated. The molecularly imprinted polymer was synthesized by the bulk polymerization, using monocrotophos, methacrylic acid, and ethylene glycol dimethacrylate as the template molecule, functional monomer, and cross‐linker, respectively. The adsorption and recognition ability of the imprinted polymer toward monocrotophos was investigated. Factors influencing preconcentration of the analytes and sensitivity of the method were optimized. Under the optimal conditions, the chemiluminescence intensity was linearly proportional to the concentration of monocrotophos range from 0.0023 to 10 mg/L, and the limit of detection of the method was 0.001 mg/L. Rape (Brassica napus) and pakchoi (Brassica rapa subsp. chinensis) samples spiked with monocrotophos at three levels were analyzed by the developed method with recoveries between 89.3% and 105.9%. This method was successfully applied to the determination of monocrotophos in spinach samples, and the results were verified by gas chromatography method. [ABSTRACT FROM AUTHOR]

BACKGROUND Organophosphate pesticide residues are harmful to human health because of their potential mutagenic and carcinogenic properties. Therefore, it is of great importance to development an accurate and reliable analytical method to prevent their uncontrolled effects on environmental pollution and human health. RESULTS This study reports a new method of molecularly imprinted solid-phase extraction coupled with high-performance liquid chromatography (MISPE-HPLC) for simultaneous determination of two organophosphate pesticides residues. Two types of molecularly imprinted polymers (MIPs) were prepared using the trichlorfon and monocrotophos as the template molecule, respectively, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The recognition ability and adsorption-desorption dynamic of each imprinted polymer toward the trichlorfon or monocrotophos were characterised. Using the mixture of trichlorfon-MIP and monocrotophos-MIP (20:80, wt/wt) as solid-phase extraction sorbent, the factors affecting the pre-concentration on the analytes and the sensitivity of the MISPE-HPLC method were optimised. Under optimal condition, the linear range was 0.005-1.0 mg L−1. The limit of detection was 4.2 µg g−1 for trichlorfon, and 1.2 ng g−1 for monocrotophos. The peak area precision [Relative standard deviation (RSD)] for three replicates was 2.9-4.5%. The blank rape and cauliflower samples spiked with trichlorfon and monocrotophos at 0.05 and 0.005 µg g−1 levels were extracted and determined by this method with recoveries ranging from 88.5% to 94.2%. Moreover, this method was successfully applied to the quantitative detection of the trichlorfon and monocrotophos residues in leek samples. CONCLUSION With good properties of high sensitivity, simple pre-treatment and low cost, this MISPE-HPLC method could provide a new tool for the rapid determination of multi-pesticide residues in the complicated food samples. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

An organic-inorganic hybrid functionalized material was successfully synthesized by a surface molecular imprinting technique combined with a nonhydrolytic sol-gel (NHSG) process using acrylamide (AA) as the template, methacrylic acid as the functional monomer, methacryloxypropyltrimethoxysilane as the cross-linker and magnetic chitosan (CTS) microspheres as the support material. The adsorption ability and selectivity of this material toward AA was characterized. Experimental results showed that the imprinted polymer exhibited better recognition and selective performance toward AA than the nonimprinted polymer (NIP). The saturated binding capacity (Qmax) was 104.68 mg/g, and the equilibrium dissociation constant was 263.16 mg/mL. This prepared material also offered fast kinetics for the adsorption and desorption of AA. After shaking for 5 min, an adsorption capacity of 4.71 mg/g was obtained, and it almost reached the adsorption equilibrium within 90 min. [ABSTRACT FROM PUBLISHER]

In this study, a novel functionalized material for selective recognition of Sudan III was synthesized by a molecular imprinting technique in combination with a sol-gel process on the activated silica gel surface. The imprinted polymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and adsorption experiments. The results showed that this material exhibited a high adsorption capacity with selective ability toward Sudan III. Its saturated binding capacity was 12.16 mg/g. It offered a fast kinetics for the adsorption of Sudan III; 71.67% of the saturated adsorption capacity was obtained within a shaking period of 5 min, and the adsorption equilibrium was almost reached within 120 min. With good performance, this functionalized polymer was suitable as a new selective sorbent for application in solid phase extraction. [ABSTRACT FROM AUTHOR]

In this study, a hydrophilic polymer was synthesized by a room temperature ionic liquid-mediated surface molecular imprinting technique in combination with a sol-gel process using water as solution. The novel polymer was evaluated and characterized, and the results indicated that it exhibited higher adsorption capacity and more selective ability in water environment than the traditional imprinted polymer synthesized using methanol. The saturated binding capacity of the novel polymer was 9.62 mg g-1 and the equilibrium dissociation constant was 769.2 m g mL-1. This imprinted polymer offered a faster kinetics for the adsorption of olaquindox in water, 1.45 mg g-1 of binding capacity was obtained within a shaking period of 60 min, and the adsorption equilibrium was almost reached within 180 min. [ABSTRACT FROM AUTHOR]

Pesticide residue in vegetables is a serious problem that has adverse effects on human health. In our study, we designed and synthesized a molecularly imprinted polymer that can selectively recognize trichlorfon. Using the polymer material as biomimetic antibody, we developed a biomimetic immunoassay-capillary electrophoresis method with improved sensitivity for the detection of trichlorfon. We evaluated the competitive reactions between HRP labeled trichlorfon hapten and free trichlorfon with the biomimetic antibody. Factors that affected the sensitivity of our method were tested in detail. Under optimal conditions, the limit of detection (LOD, IC 15 ) and the sensitivity (IC 50 ) of this method were 0.16 mg L −1 and 0.13 μg L −1 for trichlorfon. We used this method to determine the trichlorfon spiked in the kidney bean and cucumber samples with recoveries ranging from 78.8% to 103%. We also detected residual trichlorfons in the leek samples, and these results were verified by gas chromatography method. [ABSTRACT FROM AUTHOR]

A direct competitive biomimetic immunosorbent assay method based on molecularly imprinted polymer was developed for the determination of trichlorfon. A CdSe/ZnS quantum dot label was used as the marker. The hydrophilic imprinted film was synthesized directly on the surface of a 96-well plate, and characterized by Fourier-transform infrared spectroscopy and thermo-gravimetric analyses. The method exhibited high stability, selectivity, and sensitivity. Under optimal conditions, the limits of detection and sensitivity of the biomimetic immunosorbent assay method were 9.0 μg L −1 and 5.0 mg L −1 (0.1 mg kg −1 and 62.5 mg kg −1 for vegetable sample), respectively. Low cross-reactivity values of 19.2% and 15.6% were obtained for the structural analogues. Spinach and rape samples spiked with trichlorfon were extracted and determined by this method with recoveries ranging from 83.6% to 91.1%. The method was applied for the detection of trichlorfon residues in leek and cucumber samples, and results correlated well with those obtained using GC. [ABSTRACT FROM AUTHOR]