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Magnetic molecular imprinted polymers with ionic liquid used as an auxiliary solvent (IL@MMIPs) for the recognition of the methyl carbamate pesticide carbaryl (CBR) in foodstuff have been synthesized. The properties and application of IL@MMIPs were determined. The kinetic and isotherm adsorption processes were found to follow the pseudo-second-order and the Scatchard models, respectively. The selective experiment showed that the IL@MMIPs exhibited good selectivity to CBR compared to magnetic nonimprinted polymers with IL (IL@MNIPs). By using the IL@MMIPs as an adsorbent for the enrichment of CBR in food samples, the limit of detection (LOD, S/N = 3) and the limit of quantitation (LOQ, S/N = 10) of this method were 3 μg kg−1 and 10 μg kg−1, respectively. Compared with the traditional method, the IL@MMIP method has better recoveries (83.23–99.83%), precision (1.12–2.09%), and stabilization (intraday, 1.08–2.81%; interday, 2.26–3.30%). IL@MMIPs are an ideal adsorbent that could be applied to conveniently detect CBR in complex food, and the proposed method can be considered as a selective and sensitive alternative to traditional methods with affordable cost, avoiding the complex pretreatment procedure. [ABSTRACT FROM AUTHOR]

The authors have synthesized a phosphorescent probe of type SiO2-QD-MIP, where QD stands for Mn:ZnS quantum dots and MIP is a polymer coating that was molecularly imprinted with cephalexin. The nanoprobe with high specificity was prepared via sol-gel polymerization using thioglycolic acid (TGA)-modified QDs as luminescent materials, cephalexin as the template, 3-aminopropyltriethoxysilane as the functional monomer, and tetraethoxysilane as the crosslinking agent. The SiO2-QD-MIPs were characterized by X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectrometry. The orange emission of the probe, with excitation/emission maxima at 295/590 nm, decreases linearly in the 2.5–50 μg·L−1 cephalexin concentration range with a limit of detection (LOD) of 0.81 μg·L−1. The nanoprobe was successfully applied to the determination of cephalexin in (spiked) raw milk and milk powder. The recoveries ranged from 91.7 to 103.7%. [ABSTRACT FROM AUTHOR]

• Magnetic molecular imprinted polymers were synthesized successfully for cephalexin. • The MMIPs of cephalexin have high adsorption capacity, short adsorption equilibrium time and outstanding magnetism. • MMIPs exerted good recovery, precision, and stability in determining CFX in food. • Along with simplicity, MMIPs-HPLC method is applicable to food sample. A highly selective and effective method was successfully developed using magnetic molecular imprinted polymers (MMIPs) as solid-phase extraction (SPE) coupled with high performance liquid chromatography-ultraviolet detector (HPLC-UV) to rapidly determine cephalexin (CFX) in complex animal-derived food. MMIPs were creatively synthesized via suspension polymerization using Fe 3 O 4 magnetic nanoparticles as supporter, CFX as template, acrylamide (AM) as functional monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. The MMIPs were characterized using X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The binding process fitted well with pseudo-second-order model with good selectivity. Scatchard plot analysis suggested that MMIPs have two types of binding sites with the Q max of 24.18 mg g−1 and 40.25 mg g−1, respectively. And Langmuir model proved that the recognition sites were uniformly distributed in a monolayer on the surface of MMIPs. The methodological assessment showed good applicability of MMIPs with excellent recovery (85.5%–94.0%), precision (1.2%–2.4%), and stability (intra-day 1.3%–3.6%; inter-day 2.6%–4.3%) in determining CFX content. In addition, the linearity of the calibration curve was good in the range of 0.02–5.00 mg L−1, with a sensitive detection limit of 5.00 μg kg−1. The results above suggest that the obtained MMIPs exert good performance for separation of CFX in animal-derived food, and the proposed method is suitable for the reliable determination of CFX in complex samples. [ABSTRACT FROM AUTHOR]

Abstract In this study, an efficient, selective, and simple analytical method for the extraction of chloramphenicol (CAP) from food using magnetic molecularly imprinted polymers (MMIPs) as the solid-phase extraction (SPE) sorbent was successfully developed. MMIPs with varying ratios of methacrylic acid to acrylamide were prepared by suspension polymerization on the surface of double-bond-modified Fe 3 O 4 magnetic nanoparticles. Further, these MMIPs were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, as well as using a vibrating sample magnetometer. Furthermore, the adsorption capacities of MMIPs and MNIPs were investigated by binding experiments. Methodology evaluation for the detection of CAP from food was carried out using MMIPs as the SPE sorbent. By using an external magnetic field, MMIPs were separated by a simple and rapid method. The diameter of the so-obtained MMIPs, exhibiting good monodispersity, was 400–700 nm. The MMIPs exhibited the maximum apparent adsorption capacity of up to 42.60 mg g−1 with good selectivity. For the detection of food samples, the linear response range was 0.02–10.00 mg L−1, with a detection limit of 10 μg L−1, and intra- and inter-day stabilities ranged from 1.34% to 1.89% and from 1.76% to 2.77%, respectively, with good recoveries (95.31%–106.89%) and satisfactory relative standard deviations (1.21%–2.60%). Highlights • Two kinds of functional monomers were used to prepare MMIPs targeted to chloramphenicol for the first time. • MMIPs have high adsorption capacity and selectivity for chloramphenicol. • The method which used MMIPs showed sensitive detection limit, high recoveries, good precision and stability. [ABSTRACT FROM AUTHOR]

• Soybean hulls as raw materials can improve resource utilization and reduce costs. • Molecular imprinting techniques confer selectivity to common adsorbents. • Biochar is used as a carrier to improve the adsorption and mass transfer rate. • Solid-phase extraction improves the convenience of solid-liquid separation. The residue of carbaryl in food is a threat to human health. In this study, activated soybean shell biochar (A-SBC) was used as a carrier, methacrylic acid (MAA) was used as a functional monomer, and carbaryl was used as a template molecule to synthesize the activated biochar surface molecularly imprinted polymer (A-SBC@MIP). The synthesized A-SBC@MIP was characterized by SEM, FT-IR, XRD and XPS techniques, and then applied as adsorbent for carbaryl removal. The adsorption capacity of A-SBC@MIP for carbaryl was 8.6 mg‧g−1 and the imprinting factor was 1.49 at the optimum ionic strength and pH. The kinetic and isothermal data indicated that it had fast mass transfer rate and high binding capacity(Qmax=47.9 mg‧g−1). A-SBC@MIP showed good regenerative properties and the adsorption of carbaryl was excellent in its structural analogues. A solid-phase extraction (SPE) column composed of A-SBC@MIP was developed for the detection of rice and corn under optimized conditions, with recoveries of 93–101% for the spiked carbaryl. The limit of detection (LOD) of the method was 3.6 μg‧kg−1 with good linearity (R2=0.994) in the range of 0.01–5.00 mg‧L−1. The results show that the developed MIPs-SPE can enrich carbaryl from food samples as a specific and cost-effective method. [ABSTRACT FROM AUTHOR]

[Display omitted] • A MQD-MIPs probe has been firstly fabricated for detecting norfloxacin residual in food. • Mn-Zns QDs endow the probe better anti-interference to analyte with self- fluorescence. • Fe 3 O 4 nanoparticles as core improved the separation speed and stability of the probe. • The possible phosphorescence quenching mechanism of MQD-MIPs to norfloxacin was discussed. • The peobe can rapidly detect trace norfloxacin (LOD = 0.80 μg·L−1) within 40 min. This paper reports the development of a novel probe based on magnetic room-temperature phosphorescence quantum dots with molecularly imprinted polymers (MQD-MIPs) for the rapid detection of trace norfloxacin (NFX) residual in complex food matrix. The highly selective probe was constructed by surface molecular imprinting technology using magnetic materials (Fe 3 O 4 nanoparticles) as core, Mn-doped ZnS quantum dots (Mn-ZnS QDs) as phosphorescent materials, NFX as template, 3-aminopropyltriethoxysilane as functional monomer, and tetraethoxysilane as crosslinking agent. The as-obtained MQD-MIPs were characterized in detail by transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectrometry, and vibrating sample magnetometer. A magnetic strength of 37.64 emu g−1 was recorded. Also, the probe displayed excellent room temperature phosphorescence properties with excitation/emission peaks at 300/590 nm. Under the optimized conditions, the detection time was less than 40 min, phosphorescence intensity varied linearly with concentration from 1 to 90 μg·L−1, and detection limit reached as low as 0.80 μg·L−1. Furthermore, the MQD-MIPs-based probe successfully detected norfloxacin residues in spiked fish and milk samples with recoveries of 90.92–111.53% and RSD <7%, outperforming the standard control method-HPLC-FLD (recoveries of 85.89–118.28%). [ABSTRACT FROM AUTHOR]