Use of phenyl/tetrazolyl-functionalized magnetic microspheres and stable isotope labeled internal standards for significant reduction of matrix effect in determination of nine fluoroquinolones by liquid chromatography-quadrupole linear ion trap mass spectrometry

Advances in magnetic analytical extraction techniques for detecting antibiotic residues in edible samples

The widespread use of antibiotics in agricultural and animal husbandry to treat bacterial illnesses has resulted in a rise in antibiotic-resistant bacteria. These bacteria can grow when antibiotic residues are present in food items, especially in edible animal products. As a result, it is crucial to monitor and regulate the amounts of antibiotics in food. Magnetic analytical extractions (MAEs) have emerged as a potential approach for extracting antibiotic residues from food using magnetic nanoparticles (MNPs). Recent improvements in MAEs have resulted in the emergence of novel MNPs with better selectivity and sensitivity for the extraction of antibiotic residues from food samples. Consequently, this review paper addresses current developments in MAE for extracting antibiotic residues from edible samples. It also provides a critical analysis of contemporary MAE practices. The current issues and potential future developments in this field are also discussed, thereby providing a framework for future study paths.

Triblock copolymer–grafted restricted access materials with zwitterionic polymer outer layers for highly efficient extraction of fluoroquinolones and exclusion of proteins

High-selectivity and high-exclusion restricted access materials (RAMs) benefit the analysis of biological samples. Herein, triblock copolymer-functionalized poly(4-vinylbenzyl chloride-co-divinylbenzene) (P_VBC/DVB) microspheres were prepared via the sequential surface-initiated atom radical polymerization of hydrophobic styrene (St), ionic vinylimidazole (VIm), and zwitterionic sulfobetaine methacrylate (SBMA), affording RAMs with multiple interaction-adsorption sites and zwitterionic polymer exclusion sites on the internal and external surfaces of P_VBC/DVB. The preferential extraction of fluoroquinolones (FQs) is realized based on the hydrophobic/π-π/ion exchange interactions due to the grafted poly-St-VIm, and the zwitterionic poly-SBMA block in the triblock copolymers can efficiently exclude various proteins. A sensitive detection method for FQs in chicken was established by solid phase extraction with RAMs as adsorbent combined with UPLC-MS/MS, achieving wide linearity (2.0-200.0 ng mL^-1), low limit of detection (0.5 μg kg^-1) and limit of quantification (1.5 μg kg^-1), and good inter- and intraday precision with satisfactory recoveries (104.1%-117.7% and 115.3%-121.2% with RSDs < 12%).

Advances of stable isotope technology in food safety analysis and nutrient metabolism research

Food quality, safety, and the regulatory metabolism of food nutrients in cells are primary factors in determining human health. However, residues of undesirable or hazardous compounds in food products and dysregulation in the nutrient metabolism inevitably occur occasionally. For years, chromatography-mass spectrometry technology has been recognized as an essential research tool in food analysis and nutrient metabolism research, and it is more accurate and robust when coupled with stable isotopes. In this study, we summarize the applications of stable isotope technology in the quantification of contaminant residues (pesticides, veterinary drugs, mycotoxins, polycyclic aromatic hydrocarbons, and other hazardous compounds) in foods and in the nutrients (glucose, lipids, amino acids and proteins) metabolism research. The aim of this review was to serve as a reference for providing effective analysis techniques for protecting food quality and human health, and to pave the way for the broader application of stable isotope technology.

Self-synthesized TiO2 nanoparticles-pH-mediated dispersive solid phase extraction coupled with high performance liquid chromatography for the determination of quinolones in biological matrices

A simple and efficient pH-mediated dispersive solid phase extraction (dSPE) based on terbium doped titanium dioxide nanoparticles (TiO₂-Tb NPs) combined with high performance liquid chromatography (HPLC) has been firstly developed for the determination of quinolones (QNs) in various biological samples. The adsorption kinetics and isotherms were investigated to indicate that the kinetic and equilibrium adsorption were well-described by pseudo-second order kinetic and Henry, Langmuir isotherm model, respectively. The parameters influencing the extraction performance were systematically investigated. The QNs are transferred into TiO₂-Tb NPs in the first step at pH = 6.0 and eluted into acidic aqueous phase at pH = 2.5 in the second step. Under the optimum extraction and determination conditions, a linearity range with the coefficient of determination (R²) from 0.9977 to 0.9991 were obtained in a range of 10-10,000 ng mL^-1. The limits of detection (LODs) based on a signal-to-noise ratio of 3 were 3.3 ng mL^-1. The recoveries of the three QNs in human urine, rabbit plasma and serum samples ranged from 69.3% to 117.6%, with standard deviations ranging from 2.4% to 9.9%. Therefore, this pH-mediated dSPE-HPLC method exhibited the advantages of remarkable sensitivity, ease of operation, rapidity, low cost and environmental friendliness.

Polyethyleneimine-functionalized Fe3O4/attapulgite particles for hydrophilic interaction-based magnetic dispersive solid-phase extraction of fluoroquinolones in chicken muscle

Fluoroquinolone (FQ) residues in foods of animal origin may threaten public health but are challenging to determine because of their low contents and complex matrices. In this study, novel polyethyleneimine-functionalized Fe₃O₄/attapulgite magnetic particles were prepared by a simple co-mixing method and applied as hydrophilic sorbents for the magnetic dispersive solid-phase extraction (MSPE) of three FQs, i.e., ciprofloxacin, norfloxacin, and enrofloxacin, from chicken muscle samples. The preparation of the magnetic particles was of high reproducibility and the products could be reused many times with high adsorption capacity. The key experimental factors possibly influencing the extraction efficiencies, including sample solution, extraction time, sample loading volume, desorption solution, desorption time, and elution volume were investigated. Under optimum MSPE conditions, the analytes in chicken muscle samples were extracted and then determined by RPLC-MS/MS in MRM mode. Good linearity was obtained for the analytes with correlation coefficients ranged from 0.9975 to 0.9995. The limits of detection were in the range of 0.02-0.08 μg kg^-1, and the recoveries of the spiked FQs in chicken muscle samples ranged from 83.9 to 98.7% with relative standard deviations of 1.3-6.8% (n = 3). Compared with the traditional MSPE methods based on hydrophobic mechanism, this hydrophilic interaction-based method significantly simplifies the sample pretreatment procedure and improves repeatability. This method is promising for accurate monitoring of FQs in foods of animal origin.

Determination of fluoroquinolones in foods using ionic liquid modified Fe3O4/MWCNTs as the adsorbent for magnetic solid phase extraction coupled with HPLC

In this work, a simple and sensitive method based on Fe₃O₄/multi-walled carbon nanotubes/ionic liquid (Fe₃O₄/MWCNTs/IL) as the adsorbent for magnetic solid phase extraction coupled with high performance liquid chromatography was developed for the determination of trace fluoroquinolones in foods. After a simple one-pot solvothermal synthesis, Fe₃O₄/MWCNTs were further modified with an amine-terminated ionic liquid to enhance their dispersibility and extraction capacity. The morphology, structure and magnetic properties of the composite adsorbent were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectrometry and vibrating-sample magnetometry. Under the optimized extraction and detection conditions, the studied fluoroquinolones were enriched effectively and separated well and their UV signals were linear to their concentrations in the range of 4-1000 ng mL^-1, with correlation coefficients ranging from 0.9958 to 0.9990. The enrichment factors were 29.1-43.9 fold and the limits of detection were 0.33-0.78 ng mL^-1. The spiked recoveries were 85.4-105.9% for milk and 85.2-103.7% for pork samples, with relative standard deviations of 0.8-5.7%. The developed method provided a fast, sensitive and reliable determination platform for fluoroquinolones in complex real samples.

Au nanoparticle preconcentration coupled with CE-electrochemiluminescence detection for sensitive analysis of fluoroquinolones in European eel (Anguilla anguilla)

In this work, a novel method based on gold nanoparticle preconcentration coupled with CE for electrochemiluminescence detection of ciprofloxacin, enrofloxacin, ofloxacin, and norfloxacin in European eels was developed. The addition of gold nanoparticles induced the rapid enrichment of fluoroquinolones, which was simpler than the conventional enrichment approaches such as solid phase extraction and solid-phase microextraction. More than 100 times enrichment was observed after gold nanoparticle aggregation-based preconcentration. The CE-electrochemiluminescence parameters that affected the separation and detection were optimized. Under the optimized conditions, the linear ranges for the four fluoroquinolones were 0.090-8.0 μmol L-1 with the detection limits between 0.020 and 0.050 μmol L-1. The proposed approach showed the advantages of high sensitivity, high selectivity, a wide linear range, and a low detection limit. It was used to analyze fluoroquinolones in European eel, and the results showed that the developed method can satisfy the detection requirements for fluoroquinolone determination in aquatic products set by China and the European Union.

Comparison of Sample Preparation and Determination of 60 Veterinary Drug Residues in Flatfish Using Liquid Chromatography-Tandem Mass Spectrometry

This study was performed to optimize the analytical method for multi-residues of 60 compounds in flatfish samples. Three sample preparation methods were tested to identify the optimal recovery conditions for target analytes. As a result, 10 mL of water/acetonitrile (1:4, v/v) was used to extract analytes from fish samples. For purification, C₁₈ and 10 mL of acetonitrile saturated hexane were used to treat the samples. After evaporation and reconstitution, the fish samples were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry. The proposed method was validated according to the CODEX guidelines (CAC/GL-71). Our results showed the recoveries of 73.2%-115% and coefficients of variation of 1.6%-22.1%. The limit of quantification was 0.0005-0.005 mg/kg in the fishery products. In analysis of real samples, no samples exceeded the limit of quantification. This analytical method can be used for multi-residue screening and confirmation of the residues of veterinary drugs in fishery products.