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Tetracyclines and fluoroquinolones are common antibacterial drugs used in aquaculture, and their residues may pose a risk to human health. The low concentration of drug residues and complex matrixes such as fats and proteins in aquatic products necessitate the urgent development of efficient sample pretreatment methods. Solid phase extraction (SPE) is the most common sample pretreatment method, in which the core is an adsorbent. Compared with traditional SPE adsorbents, nanofiber mat (NFsM) has more interaction sites because of their large specific surface area. Furthermore, NFsMs modified with specific functional groups can significantly improve the extraction efficiency of tetracyclines and fluoroquinolones. Polydopamine (PDA) is spontaneously synthesized by the oxidative self-polymerization of dopamine-hydrochloride in alkaline solutions (pH>7.5). Because of its rich amino and catechol groups, PDA can form π-π stacking, electrostatic attraction, hydrophobic interaction, and hydrogen bonding interactions with target molecules. By exploiting the above advantages, polystyrene (PS) NFsM, as a template, was prepared by the electrostatic spinning method, and PDA-PS NFsM was obtained by functional modification of PDA through self-polymerization. Fourier transform infrared spectroscopy (FT-IR) and field-emission scanning electron microscopy (FESEM) were used to characterize the synthesized PS NFsM and PDA-PS NFsM. It was proved that PDA was successfully modified on the PS NFsM, with the SEM images revealing a rough outer core shell structure and an inner honeycomb structure. Subsequently, the handmade SPE column with PDA-PS NFsM was completed. A novel and efficient screening analytical method based on PDA-PS NFsM for the simultaneous determination of three tetracyclines (tetracycline (TET), chlortetracycline (CTC), and oxytetracycline (OTC)) and three fluoroquinolones (enrofloxacin (ENR), ciprofloxacin (CIP), and norfloxacin (NOR)) in fish by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established. The SPE procedure was optimized to develop an efficient method for sample preparation. Evaluate parameters including the amount of NFsM usage, ionic strength, flow rate of the sample solution, composition of eluent, and breakthrough volume were investigated. Only (20±0.1) mg of PDA-PS NFsM was sufficient to completely adsorb the targets, and the analytes retained on NFsM could be eluted by 1 mL of formic acid-ethyl acetate (containing 20% methanol) (1∶99, v/v). The residues were redissolved in 0.1 mL 10% methanol aqueous solution containing 0.2% formic acid. In addition, no adjustment of the pH and ionic strength of the sample solutions was required, and the breakthrough volume was 50 mL. The limits of detection (LODs) and limits of quantification (LOQs) of the six target compounds were measured at 3 times and 10 times the signal-to-noise ratio (S/N), respectively. The LODs and LOQs were 0.3-1.5 μg/kg and 1.0-5.0 μg/kg, respectively. The linear ranges of the six target compounds were LOQ-1000 μg/kg, and the coefficient of determination (R2) was greater than 0.999. To evaluate the accuracy and precision, blank spiked samples at three levels (low, medium, and high) were prepared for the recovery experiments, and each level with six parallel samples (n=6). The recoveries ranged from 94.37% to 102.82%, with intra-day and inter-day relative standard deviations of 2.38% to 8.06% and 4.10% to 9.10%, respectively. To evaluate the purification capacity of PDA-PS NFsM, the matrix effects before and after SPE were calculated and compared. Matrix effects before SPE were -12.98% to -38.68%. After the completion of SPEbased on PDA-PS NFsM, the matrix effect of each target analyte was significantly reduced to -2.15% to -7.36%, which proved the significant matrix removal capacity of PDA-PS NFsM. Finally, the practicality of this method was evaluated by using it to analyze real samples. This SPE method based on PDA-PS NFsM is efficient, practical, and environmentally friendly, and it has great potential for use in the routine monitoring of drug residues in fish.

Using electrospun chitosan/polyethylene oxide nanofibers mat (CS/PEO NFM) as carrier, Cu@CS/PEO NFM, a new tetracycline (TC) solid-state colorimetric sensor, were simply prepared by directly immobilizing Cu

Sensitive and real-time tetracycline (TC) monitoring method is of great significant for food safety and human health. Herein, a novel TC dynamic sensing mode based on a solid-phase nanofiber mat (NFM) sensor SP@COF/SDBS/PS NFM was constructed for the first time, where spiropyran-modified covalent organic framework (SP@COF) with red emissions (λ

Tetracyclines and fluoroquinolones are common antibacterial drugs used in aquaculture, and their residues may pose a risk to human health. The low concentration of drug residues and complex matrixes such as fats and proteins in aquatic products necessitate the urgent development of efficient sample pretreatment methods. Solid phase extraction (SPE) is the most common sample pretreatment method, in which the core is an adsorbent. Compared with traditional SPE adsorbents, nanofiber mat (NFsM) has more interaction sites because of their large specific surface area. Furthermore, NFsMs modified with specific functional groups can significantly improve the extraction efficiency of tetracyclines and fluoroquinolones. Polydopamine (PDA) is spontaneously synthesized by the oxidative self-polymerization of dopamine-hydrochloride in alkaline solutions (pH7.5). Because of its rich amino and catechol groups, PDA can form

Polydopamine polystyrene nanofibers mat (PDA-PS NFsM) was prepared as an adsorbent for the simultaneous removal of multiple antibiotic residues in environmental water for the first time. PDA-PS NFsM can directly be used to adsorb 18 antibiotic residues belonging to 8 classes without any pretreatment of water samples. The adsorption process was completed within 5 min. All antibiotics could be removed at the same time, and the removal rate of each target was above 85%. Moreover, the used PDA-PS NFsM can be easily separated from the environmental water by taking out directly, and can be reused for 10 times after simple regeneration. The thermodynamic and kinetic properties of PDA-PS NFsM adsorption of antibiotic residues were further investigated consequently. It was found that the adsorptions of PDA-PS NFsM to the targets were spontaneous and endothermic process (ΔG 0, ΔS>0). The results of adsorption kinetic experiments illustrated that the adsorption process was rapid, the adsorption equilibrium of which can be reached in 5 min. Adsorption isotherm experiments proved that the adsorption process of PDA-PS NFsM was consistent with Langmuir adsorption (R2 > 0.994), and the maximum adsorption capacity of PDA-PS NFsM towards all targets were 123.76 mg g−1. The developed method is rapid and simple, and can efficiently adsorb and remove a variety of antibiotics in environmental water, which has good practical application prospect.

Polydopamine/polystyrene fibers mat (PDA-PS FsM) was prepared as a novel solid phase extraction (SPE) adsorbent for the simultaneous extraction of multi-class veterinary drug residues in animal-original foods. On this basis, a screening method for the determination of 18 veterinary drug residues in 8 classes by UPLC-MS/MS was established. PDA-PS FsM was confirmed to have good adsorption-desorption performance. By comparing the matrix effect before and after SPE, it was proved that PDA-PS FsM had significant matrix removal ability. The whole sample preparation process was less than 5 min, only 20 mg PDA-PS FsM and 2.5 mL of organic solvent were needed. The limits of detection of the target analytes ranged from 0.1 to 3.2 μg kg−1, and the recoveries ranged from 92.59% to 102.86%, with the intra-day and inter-day relative standard deviations of 2.11%–10.57%, revealing satisfactory accuracy and precision. Finally, the practicability of the method was evaluated.

In this study, polyaniline modified polyacrylonitrile nanofibers mat (PANI NFsM) was prepared as a novel adsorbent for the solid-phase extraction (SPE) of non-steroidal anti-inflammatory drug residues in meat or egg samples. The solvent extracts of samples were simply diluted with water to perform the SPE, and then the eluent was directly analyzed. Significant reduction of the matrix effect was obtained after SPE using only 5 mg of PANI NFsM. The entire sample preparation time is 5–10 times lower than the existing methods. The limits of detection of the target analytes ranging from 0.6 to 12.2 µg kg−1 had already met the demand of food safety monitoring by only 1 g sample. The recoveries ranged from 85.18% to 107.31%, with the intra-day and inter-day relative standard deviations of 2.74% to 16.01%, revealing satisfactory accuracy and precision. Finally, real samples analyses were applied to verify the practicability of the method.

Pyrene functionalized polyacrylonitrile nanofibers mat (Py-PAN NFM) was prepared via a green approach based on deep eutectic solvents. The Py-PAN NFM was further employed as solid-state fluorescent sensors for determining 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT) in real water samples. In order to adapt to the hydrophobicity of Py-PAN NFM surface, the water samples were extracted by dichloromethane, and then the extraction solvents were directly dropped onto the Py-PAN NFM. The conversion of sample polarity ensures that Py-PAN NFM does not need to be immersed in the water samples for a long time. The target TNT and DNT can immediately interact with the pyrene fluorophores on surface of Py-PAN NFM, thus accelerating the detection speed. Because the targets were also enriched through the conversion process, the sensing sensitivity has been significantly improved and the limits of detection of TNT and DNT can reach 8.81 × 10−9 M and 2.74 × 10−8 M, respectively. The Stern–Volmer plots for fluorescence quenching by TNT and DNT displayed an overall linearity in the entire tested concentration range with quenching constants of 2.57 × 106 M−1 and 3.15 × 105 M−1, respectively. Moreover, the selectivity study indicated that other nitro compounds have an insignificant effect on the fluorescence sensing detection of TNT and DNT, and Py-PAN NFM can be reused at least 6 times without degradation in fluorescence-quenching performance. The theoretical calculations demonstrated that photoinduced electron transfer was involved in the quenching process and the fluorescence lifetime measurements revealed that a static quenching mechanism was suitable to explain the quenching behavior. The experimental results fully proved the practicability of this method in the rapid and sensitive monitoring of nitroaromatic compounds.