Rapid multi-residue LC-MS/MS determination of nitrofuran metabolites, nitroimidazoles, amphenicols, and quinolones in honey with ultrasonic-assisted derivatization - magnetic solid-phase extraction

Relative Matrix Effect in the Quantification of Nitroimidazoles and Dyes in Meat, Eggs, Shrimp, and Fish Using an Ethyl Acetate/Salting-Out Extraction and Isotope Dilution Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

This paper presents the validation of a multiresidue method for quantifying seven nitroimidazoles and four dyes in poultry, pork, beef, eggs, shrimp, and fish. The average matrix factors of standard normalized to IS (0.82-1.12) indicated no significant matrix effect, and the CV % values (2.26-12.10%) complied with the 20% limit of the Commission Implementing Regulation 2021/808. However, medium suppression (50-80%) or enhancement (120-150%) was observed in 4.29% and 2.14% of the individual matrix extracts, respectively. The linearity ranges (in μg kg-1) were 0.50-3.0 for nitroimidazoles and 0.25-1.5 for dyes, and the determination coefficients (R2) were at least 0.9688. The limits of quantitation were the lowest calibration levels. Analyte recovery and reproducibility were satisfactory (fREC: 77.95-115.0%; CV: 5.09-27.24%). The decision limits (CCα) (in μg kg-1) were 0.59-1.00 for nitroimidazoles and 0.29-0.46 for dyes and complied with the EURLs minimum method performance requirements (1.0 and 0.5 μg kg-1, respectively).

Novel solid-phase extraction promotes simultaneous colloidal gold immunochromatographic assay of malachite green, leuco-malachite green, chloramphenicol, and semi-carbazone metabolites in aquatic products

Solid phase extraction (SPE) using traditional column materials offers several advantages, but its ability to simultaneously extract and purify commonly used veterinary drugs, such as chloramphenicol, malachite green, leuco-malachite green and semi-carbazone, remains unproven.Therefore, in the present study, a rapid analytical method based on ultrasound-assisted SPE combined with colloidal gold test strips was developed and applied herein to determine the residues of these veterinary drugs in common aquatic products. Under optimized conditions, the method achieved a limit of detection in the range of 0.01-0.5 μg/kg, inter-day RSDs of the spiked samples in the ranges of 0.99-5.58 % and 1.6-7.2 %, and absolute recoveries in the range of 84.2-112.9 % using the colloidal gold immunoassay and enzyme-linked immunosorbent assay methods, respectively. The SPE column efficiently enriched the four veterinary drugs simultaneously, showing considerable potential for determining common veterinary drug residues in aquatic products.

Lignocellulosic carbon sheets-based hybrid electrochemical sensor for ultra-sensitive detection of chloramphenicol

Efficient detection of chloramphenicol (CAP) in the environment and food products is crucial for addressing global health and environmental safety concerns. This study presents the development of a cost-effective hybrid electrocatalyst comprising lignocellulosic carbon sheets, graphene oxide, and manganese oxide (LCSs/GO@MnO2) for CAP detection using a simple electrochemical sensor fabricated on a glassy carbon electrode (GCE) substrate. The synergistic interaction between LCSs, GO, and MnO2 enhance the electroactive surface area of GCE, facilitating effective dispersion and electrode modification. This composite material significantly improves electrical conductivity and provides numerous electroactive sites for electrochemical CAP detection via voltammetric techniques. The developed sensor demonstrates a rapid electron transfer rate, enhancing electrode sensitivity for CAP detection at a low overpotential (-0.5717 V) and an optimal pH (7.0). The sensor exhibits a wide linear range (0.017-477.247 μM), excellent sensitivity (105.22 μA μM-1 cm-2), and a low limit of detection (1.2 nM) with enhanced charge carrier efficiency. Additionally, the sensor shows good cycle stability, reproducibility, selectivity, and trace-level CAP sensing applicability in food samples at a low cost. These features make the sensor a promising platform for monitoring antibiotics in various applications.

Development of a novelly selective HPLC-chemiluminescence method by targeting degradation intermediates of nitroimidazoles and its application in animal food products

Residues of nitro-containing drugs in food and the environment have aroused social concern because of their excessive use for the treatment of human and animal diseases. The disadvantages of complex and time-consuming pretreatments in existing methods make it imperative to develop novel methods. Herein, with the aid of recognition probe MCLA, an excellent selective method for the detection of nitroimidazoles (NDZs) was developed based on high-performance liquid chromatography combined with ultraviolet (UV) degradation and chemiluminescence (HPLC-UV-CL). The study proposed an innovative process for the formation of SO4 •-, •OH, and •NO via advanced oxidation processes of NDZs. Six studied NDZs achieved baseline separation within 24 min with detection limits as low as 3 ng/mL (S/N = 3). The proposed method is efficient, cost-effective, and does not require complicated purification steps. This study presents a unique approach for the detection of nitro-containing contaminants and provides new insights into monitoring advanced oxidation processes.

A comprehensive review on the pretreatment and detection methods of nitrofurans and their metabolites in animal-derived food and environmental samples

In recent years, the residues of nitrofurans (NFs) and their metabolites in animal-derived food and environmental samples have gained widespread attention. The parent drugs and their metabolites have displayed significant toxicity to human health including carcinogenic, mutagenic and teratogenic effects, leading to banned in animal husbandry in many countries. Hence, monitoring the residues of NFs is necessary to guarantee public health and ecological security. This review aims to summarize and assess the structural properties, residue status, sample pretreatment methods (liquid-liquid extraction, solid-phase extraction, Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS), and field-assisted extraction), and detection methods (chromatographic analysis, immunoassay, and some innovative detection methods) for NFs and their metabolites in animal-derived food and environmental samples. This paper provides a detailed reference and discussion for the analysis of NFs and their metabolites, which can effectively promote the establishment of innovative detection methods for NFs and their metabolites residues.

CeFe nanofibrous carbon nanozyme integrated with smartphone for the point-of-care testing of norfloxacin in water

The overuse of antibiotics has led to the severe contamination of water bodies, posing a considerable hazard to human health. Therefore, the development of an accurate and rapid point-of-care testing (POCT) platform for the quantitative detection of antibiotics is necessary. In this study, Cerium oxide (CeO2) and Ferrosoferric oxide (Fe3O4) nanoparticles were simultaneously encapsulated into N-doped nanofibrous carbon microspheres to form of a novel nanozyme (CeFe-NCMzyme) with a porous structure, high surface area, and N-doped carbon material properties, leading to a considerable enhancement of the peroxidase (POD)-like activity compared with that of the CeO2 or Fe3O4 nanoparticles alone. The POD-like activity of CeFe-NCMzyme can be quenched using L-Cysteine (Cys) and subsequently restored by the addition of a quinolone antibiotic (norfloxacin, NOR). Therefore, CeFe-NCMzyme was used as a colorimetric sensor to detect NOR via an "On-Off" model of POD-like activity. The sensor possessed a wide linear range of 0.05-20.0 μM (R 2 = 0.9910) with a detection limit of 35.70 nM. Furthermore, a smartphone-assisted POCT platform with CeFe-NCMzyme was fabricated for quantitative detection of NOR based on RGB analysis. With the use of the POCT platform, a linear range of 0.1-20.0 μM and a detection limit of 54.10 nM were obtained. The spiked recoveries in the water samples were ranged from 97.73% to 102.01%, and the sensor exhibited good accuracy and acceptable reliability. This study provides a portable POCT platform for the on-site and quantitative monitoring of quinolone antibiotics in real samples, particularly in resource-constrained settings.

Two flavors in adulterated sesame oil: discovery, confirmation, and content regularity study

Exploring and accurately detecting new adulteration markers in sesame oil is an important measure for sesame oil adulteration monitoring. In this study, two endogenous flavors sulfurol and γ-nonalactone which can be used as potential adulteration markers were first discovered in sesame oil and accurately quantified. First, the two endogenous flavors were discovered using gas chromatography-mass spectrometry (GC-MS), and their structures were confirmed by comparing the mass spectrograms with the NIST spectral library. Then the liquid chromatography-tandem mass spectrometry (LC-MS/MS) method using direct methanol extraction pretreatment and vanillin-D3 as an internal standard was developed for rapid quantitation and application. The method was successfully validated with recoveries ranging from 88.5% to 102.2% and relative standard deviations between 2.6% and 10.5% (n = 6). The combined method of GC-MS and LC-MS/MS was indicated to be efficient and highly sensitive for detection of sulfurol and γ-nonalactone in edible oil. Subsequently, 31 sesame oils from the market were detected, revealing that 31 samples contained the identified flavors within a relatively consistent range. However, the concentration of these flavor substances in one sample was abnormally high, indicating that there was a potential risk of adulteration. Therefore, the developed method shows good potential for quality evaluation and adulteration screening of sesame oil.

Aggregation-induced-emission red carbon dots for ratiometric sensing of norfloxacin and anti-counterfeiting

The detection of trace antibiotic residues holds significant importance because it's related to food safety and human health. In this study, we developed a new high-yield red-emitting carbon dots (R-CDs) with aggregation-induced emission properties for ratiometric sensing of norfloxacin. R-CDs were prepared in 30 min using an economical and efficient microwave-assisted method with tartaric acid and o-phenylenediamine as precursors, achieving a high yield of 34.4 %. R-CDs showed concentration-dependent fluorescence and aggregation-induced-emission properties. A ratiometric fluorescent probe for detecting the norfloxacin was developed. In the range of 0-40 μM, the intensity ratio of two emission peaks (I445 nm/I395 nm) towards norfloxacin show good linear relationship with its concentrations and a low detection limit was obtained (36.78 nM). In addition, complex patterns were developed for anti-counterfeiting based on different emission phenomenon at different concentrations. In summary, this study designed a novel ratiometric fluorescent probe for detection of norfloxacin, which greatly shortens the detection time and improves efficiency compared with high-performance liquid chromatography and other methods. The study will promote the application of carbon dots in anti-counterfeiting and other related fields, laying the foundation for the preparation of low-cost photosensitive anti-counterfeiting materials.