Aqueous fate of furaltadone: Kinetics, high-resolution mass spectrometry - based elucidation and toxicity assessment of photoproducts.

Furaltadone (FTD) is an antibiotic belonging to the nitrofurans group. It has been broadly used in livestock and aquaculture for therapeutic purposes, as well as for stimulating promotion. Although the European Union has imposed restrictions on the use of FTD since 1995 due to concerns regarding its toxicity, in many cases FTD has been excessively and/or illegally applied in productive animals in developing countries, because of its high efficacy and low-cost. Unlike other nitrofuran compounds, the hydrolytic and photolytic behavior of FTD in natural aquatic systems has not been thoroughly investigated. To this end, hydrolysis in different pH values and photolysis in aquatic environment, including lake, river and sea water have been both examined. Hydrolysis was found to have an insignificant impact on degradation of FTD in the aquatic environment relevant pH values, whereas indirect photolysis proved to be the main route of its elimination. The identification of tentative photoproducts (PPs) was performed using ultra high performance liquid chromatography coupled to hybrid LTQ/Orbitrap high resolution mass spectrometry. A possible pathway for photolytic transformation of FTD was proposed. Additionally, in silico simulations were used to evaluate the toxicity such as the mutagenicity of FTD and PPs. Complementary to the low-cost and time-limited simulations, an in vitro method (Vibrio Fischeri bioluminescence) was also used to assess ecotoxicity.

Simultaneous detection of three nitrofuran antibiotics by the lateral flow immunoassay based on europium nanoparticles in aquatic products.

Nitrofuran (NF) antibiotics have been banned worldwide in aquaculture due to their potential carcinogenicity and mutagenicity. Because of the short half-life of NF antibiotics, an easy and sensitive multiple lateral flow immunoassay (mLFIA) based on europium nanoparticles (EuNPs) has been successfully established to simultaneously and quantitatively detect 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), 3-amino-2-oxazolidinone (AOZ) and sodium nifurstylenate (NFS) in aquatic products. The EuNP-mLFIA assay was accomplished within 10 min. The limits of detection (LODs) for AOZ, AMOZ and NFS were 0.013, 0.019 and 0.023 ng/mL, respectively. The average recoveries of AOZ, AMOZ and NFS were 98.0-104.4%, 96.0-102.6% and 98.0-102.8%, respectively. It showed satisfactory consistency, and the feasibility was validated by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Briefly, this method will become a powerful tool for monitoring multiple NF antibiotics and provide promising applications in the field of food safety and environmental testing.

Potential negative effect of long-term exposure to nitrofurans on bacteria isolated from wastewater.

Nitrofurans are broad-spectrum bactericidal agents used in a large quantity for veterinary and human therapy. This study reports the long-term impact of two nitrofuran representatives, nitrofurantoin (NFT) and furaltadone (FTD) on the bacterial strains Sphingobacterium siyangense FTD2, Achromobacter pulmonis NFZ2, and Stenotrophomonas maltophilia FZD2, isolated from a full-scale wastewater treatment plant. Bacterial whole genome sequencing was used for preliminary strains characterization. The metabolomic, electrochemical, and culture methods were applied to understand changes in the bacterial strains after 12-month exposure to nitrofurans. The most significantly altered metabolic pathways were observed in amino acid and sugar metabolism, and aminoacyl-tRNA biosynthesis. Disrupted protein biosynthesis was measured in all strains treated with antibiotics. Prolonged exposure to NFT and FTD also triggered mutagenic effects, affected metabolic activity, and facilitated oxidative stress within the cells. Nitrofuran-induced oxidative stress was evidenced from an elevated activity of catalase and glutathione S-transferases. NFT and FTD elicited similar but not identical responses in all analyzed strains. The results obtained in this study provide new insights into the potential risks of the prolonged presence of antimicrobial compounds in the environment and contribute to a better understanding of the possible impacts of nitrofuran antibiotics on the bacterial cells.

Facile synthesis of triazine-based porous organic polymer for the extraction and determination of nitrofuran metabolites residues from meat samples with ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry.

In this work, a novel triazine-based porous organic polymers, TAPT-BPDD, was firstly synthesized by a facile method at room temperature. After characterized by FT-IR, FE-SEM, XRPD, TGA, and nitrogen-sorption experiments, TAPT-BPDD was applied as solid-phase extraction (SPE) adsorbent for the extraction of four trace nitrofuran metabolites (NFMs) from meat samples. The key parameters including the adsorbent dosage, sample pH, type and volume of eluents, type of washing solvents were evaluated in the extraction process. Combined with ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UHPLC-QTOF-MS/MS) analysis, good linear relationship (1-50 µg·kg-1, R2>0.9925) and low limits of detection (LODs, 0.05-0.56 µg·kg-1) were obtained under the optimal conditions. When spiked at different level, the recoveries were in the range of 72.7-111.6%. The adsorption isothermal model and extraction selectivity of TAPT-BPDD were also studied in detail. The results showed that TAPT-BPDD was a kind of promising SPE adsorbent for the enrichment of organics in food samples.

Fast screening method to determine metabolites of nitrofurans in chicken meat using partitioned dispersive liquid-liquid microextraction combined with HPLC/DAD.

Methods have been developed for the hydrolysis and derivatisation of protein-bound metabolites of nitrofurans and for the extraction of 2-nitrobenzaldehyde derivatives of the metabolites from chicken meat. In this work, the time needed for hydrolysis and derivatisation was reduced from the conventional 16 h to 90 min. Based on partitioned dispersed liquid-liquid microextraction, a method for extracting 2-nitrobenzaldehyde derivatives of metabolites from crude chicken meat has been developed. Under the optimised experimental conditions, enrichment factors (EFs) ranging from 92.8 to 208.9 were obtained. The method was linear over the range of 10-600 µg kg-1 with determination coefficients (r2) between 0.9979 and 0.9996. Intraday and interday repeatability expressed as a percentage RSD, ranged from 2.2% to 11.2%, and 2.7% to 12.4%, respectively. LOD of 1.07-2.25 µg kg-1 and LOQ of 3.09-6.2 µg kg-1 were obtained. The proposed method was applied in the analysis of metabolites of nitrofurans in chicken meat obtained from farmers using them for their domestic consumption and proved free of the analytes. A recovery of 85.2-109.4% with a %RSD ranging between 3.4% and 13.7% was obtained at three spiking levels. The proposed method was successfully further applied for the analysis of target analytes in chicken meat samples purchased from different supermarkets around Roodeport, Gauteng (South Africa). There was no target analyte detected in the analysed samples. Therefore, the developed methods can be used for monitoring the corresponding metabolites of nitrofurans in chicken meat.

Dual-color aggregation-induced emission nanoparticles for simultaneous lateral flow immunoassay of nitrofuran metabolites in aquatic products.

Nitrofurans such as furaltadone and nitrofurantoin are a type of synthetic broad-spectrum antibiotics. Various fluorescent nanomaterials have been used as labeling materials in immunochromatographic assays (ICAs) for nitrofurans detection. However, previous fluorescent nanomaterials can undergo aggregation-caused quenching, leading to a decrease in the detection sensitivity. In this study, we developed a multiplex immunochromatographic assay (mICA) based on dual-color aggregation-induced emission nanoparticles (AIENPs) as signal labels for the simultaneous detection of 3-amino-5-morpholino-methyl-1,3-oxazolidinone (AMOZ) and 1-aminohydantoin (AHD), which were the metabolites of furaltadone and nitrofurantoin, respectively. Under optimal conditions, the cut-off values of the mICA for derivatized AMOZ (2-NP-AMOZ) and AHD (2-NP-AHD) reached up to 3 and 5 ng/mL, respectively. These values are at least 166-and 200-fold higher than those of the commercial gold nanoparticles (GNPs)-based test strip, respectively. Furthermore, the test strip was successfully applied to the samples, with acceptable recoveries in the range of 83.0-98.2%.

Current trends in analytical strategies for the chromatographic determination of nitrofuran metabolites in food samples. An update since 2012.

Nitrofurans (NFs) are synthetic broad-spectrum antibacterial and antiparasitic drugs, which recently were extensively used in veterinary practice. In the body of animals, NFs are converted into carcinogenic and mutagenic metabolites that can be accumulated in foods of animal origin having an adverse effect on human health. Therefore, NFs are currently banned in animal husbandry and aquaculture of many countries. However, the data from monitoring the quality of food products indicate that, despite the prohibitions established by the law, they still are used not only in the developing countries but also in the European Union, due to their high antibacterial activity, low cost, and accessibility. Thus, it is of great importance for human health to develop reliable and sensitive analytical methods for monitoring NF metabolites in animal-derived foods. The objective of this review is to summarize the pretreatment strategies and chromatographic methods that have been reported during the last decade for the determination of NF metabolites in food samples, and to outline the future trends with an emphasis on the novel solutions in this area.

Verification of Bound Aminoguanidine as the Marker Residue for the Banned Antibiotic, Nitrovin, in Pig Tissues.

Nitrovin (NTV) belongs to a class of antibiotics called nitrofurans, which are classified as nonallowed pharmacologically active substances that do not have a maximum residue limit listed in EU legislation. The objectives of this study were to confirm aminoguanidine (AGN) as a suitable marker residue to monitor NTV abuse and to investigate its persistence in porcine tissues. In this work, pigs were fed with NTV-medicated feed (50 mg/kg), and tissues (kidney, muscle, and liver) and plasma were collected on different withdrawal days. All samples were analyzed for bound AGN, total AGN, and the parent drug NTV itself. The highest concentrations of AGN residues were found in the liver, while the lowest were in muscle. Parent NTV was only detected in the kidney at low levels on day 0 of withdrawal. The findings are in support of using AGN as the marker residue for monitoring the illegal use of NTV in animal-derived products.

Furazolidone and Nitrofurazone Metabolic Studies in Crucian Carp by Ultra-Performance Liquid Chromatography Tandem Mass Spectrometry.

In this work, the detection of the furazolidone (FZD) and nitrofurazone (NFZ) metabolites residuals in crucian carp are focused. Crucian carps of identical size were exposed to the mixed nitrofuran antibiotics under optimized bath conditions at a concentration of 50 mg/L, 26 ± 0.5°C for 24 h. Then, liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry (LC-ESI-MSMS) was performed after the drug exposure experiments when the nitrofuran metabolites were enriched in organisms. During the period of 0-144 h, residue levels of the 3-amino-2-oxazolidinone (AOZ) gradually decreased with a prolonged sampling time. The changing trend in semicarbazide (SEM) with the sample collection duration is divided into two stages, and its concentration showed a trend of rising first and then falling. The metabolite concentration-time curve demonstrates that 24 h was used as a sampling time, and fish muscle was selected as tissue samples in the further quantitative study. A novel crucian carp-enrichment procedure coupled to LC-ESI-MSMS quantitative method was further explored based on much metabolite data. According to the exponential curve of the SEM-to-AOZ concentration ratio at a precisely designed FZD-to-NFZ mass ratio, the final FZD content of the veterinary NFZ antibiotics was 0.069 ± 0.005% (in terms of mass).

Multi-class, multi-residue determination of 132 veterinary drugs in milk by magnetic solid-phase extraction based on magnetic hypercrosslinked polystyrene prior to their determination by high-performance liquid chromatography-tandem mass spectrometry.

A quantitative multi-class multi-residue analytical method was developed for the determination of veterinary drugs in milk by high-performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS). A total of 132 veterinary drugs investigated belonged to almost 15 classes including sulfonamides, ß-lactams, tetracyclines, quinolones, macrolides, nitrofurans, nitroimidazoles, phenicols, lincosamides, pleuromutilins, macrocyclic lactones, quinoxaline antibiotics, benzimidazoles, anthelmintics, coccidiostats and some others. A magnetic solid-phase extraction procedure was developed using magnetic hypercrosslinked polystyrene (HCP/Fe3O4) for the sample preparation prior to HPLC-MS/MS without deproteinization step. The results indicated recoveries of 85-107% for 14 sulfonamides, 85-120% for 13 ß-lactams, 89-115% for 4 tetracyclines, 82-119% for 14 quinolones, 82-115% for 8 macrolides, 97-109% for 4 nitrofurans, 84-115% for 10 nitroimidazoles, 89-114% for 3 phenicols, 86-111% for 3 lincosamides, 97-102% for 2 pleuromutilins, 72-88% for 4 macrocyclic lactones, 87-104% for 4 quinoxaline antibiotics, 76-119% for 21 benzimidazoles, 79-115% for 12 anthelmintics, 81-118% for 12 coccidiostats and 75-119 % for 5 unclassified drugs, with relative standard deviations (RSDs) of less than 20%, and the LOQs ranged from 0.05 to 1 µg kg-1. This methodology was then applied to field-collected real milk samples and trace levels of some veterinary drugs were detected.

Development and validation of a rapid LC-MS/MS method for the confirmatory analysis of the bound residues of eight nitrofuran drugs in meat using microwave reaction.

A rapid analytical method was developed and validated for the analysis of eight bound nitrofurans in animal tissue, shortening laboratory turnaround times from 4 to 2 days. The majority of methodologies for nitrofuran analysis focus on the detection of only four drugs (nitrofurantoin, furazolidone, furaltadone and nitrofurazone), and is time-consuming given the 16-h overnight derivatisation step and a double liquid-liquid extraction. In this study, the narrow scope of analysis was addressed by including further four important nitrofuran drugs (nifursol, nitrofuroxazide, nifuraldezone and nitrovin). Full chromatographic separation was achieved for the metabolites of all eight nitrofurans, using phenyl-hexyl column chemistry and a rigorous optimisation of the mobile phase additives and gradient profile. The conventional, lengthy sample preparation was substantially shortened by replacing the traditional overnight water bath derivatisation with a rapid 2-h microwave-assisted reaction, followed by a modified-QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction. This confirmatory method was fully validated in accordance with the new 2021/808/EC legislation, and was shown to perform satisfactorily when applied to incurred tissues. The decision limit (CCα) for the eight analytes ranged between 0.013 and 0.200 µg kg-1, showing abundant sensitivity given that the current RPA for nitrofurans is 0.5 µg kg-1. This innovative method can play a major role in the surveillance of the illegal use of nitrofuran drugs.

Inner-filter effect induced fluorescent sensor based on fusiform Al-MOF nanosheets for sensitive and visual detection of nitrofuran in milk.

Developing highly sensitive and visual methods for rapid detection of antibiotics is significant to ensure food quality and safety. To meet the requirement of nitrofuran antibiotics detection, luminescent fusiform Al(III)-containing metal-organic frameworks (Al-MOF) nanosheets were successfully synthesized by one-step hydrothermal method. And then, the nanosheet served as a fluorescent probe to detect nitrofuran via the inner-filter effect mechanism. The developed sensor allowed sensitive and selective detection of nitrofuran with good linear relationships. And, the detection limit (LOD) values were estimated to be 0.53, 0.838 and 0.583 µM for nitrofurazone, nitrofurantoin and furazolidone detection, respectively. The practical application of the proposed system was verified by HPLC in spiked milk samples with satisfying recoveries ranging from 88.14 to 126.21% and low relative standard deviations of 2.85 ~ 8.13%. Moreover, we designed fluorescent test papers for semi-quantitative detection of nitrofuran via naked-eye colorimetric assay. The established method provides an alternative strategy for semiquantitative detection of nitrofuran.

A competitive-type electrochemical immunosensor based on Ce-MOF@Au and MB-Au@Pt core-shell for nitrofuran metabolites residues detection.

A novel competitive-type electrochemical immunosensor based on square wave voltammetry (SWV) response was developed for the quantitative detection of 1-Aminohydantoin (AHD). To improve the conductivity of this immunosensor nanocomposites with good electrical conductivity were prepared as a signal amplification platform for the immunosensor by growing Au nanoparticles on the surface of Ce-based metal-organic framework (Ce-MOF). In addition, methylene blue (MB)-loaded Au@Pt and coating antigen (OVA-AHD) connected as a signal label. When the target was introduced, it competed with the coating antigen for the Ab, which led to a reduction in the number of signal probes bound to the Ab. The concentration of AHD can be determined by SWV detection of the MB signal loaded on the signal labels. Under optimal conditions, the wide linear range of 0.001-1000 µg /L and a low detection limit of 1.35 × 10-7 µg/L were achieved. Ultimately, the developed method displayed excellent specificity in practical applications, providing a promising probability to detect nitrofuran metabolites residues to guarantee food safety.

Determination of nitrofuran metabolites in honey using a new derivatization reagent, magnetic solid-phase extraction and LC-MS/MS.

In this study, 5-nitro-2-furaldehyde (5-NFA) was proposed as a new derivatizing agent for nitrofuran metabolites. It reacts with nitrofuran metabolites producing the parent nitrofurans (furazolidone, furaltadone, nitrofurantoin, and nitrofurazone). Magnetic hypercrosslinked polystyrene (HCP/Fe3O4) was first used for magnetic solid phase extraction (MSPE) clean-up before the determination of nitrofuran metabolite derivatives in honey via LC-MS/MS. Main parameters affecting the derivatization and MSPE efficiency were investigated in detail and the optimal conditions were found. The method was validated using honey spiked with the four metabolites at 1, 2 and 200 µg kg-1. Recoveries of >85% were achieved for the all analytes. The matrix calibration curve was fitted with the correlation coefficient (R2) > 0.99 in the range of 1-200 µg kg-1. Precision values expressed as relative standard deviation (RSD) were <12% and <15% for intra-day and inter-day precision, respectively. The limits of detection (LODs) for the nitrofuran metabolites were of 0.1-0.3 µg kg-1 and the limits of quantitation (LOQs) were of 0.3-1.0 µg kg-1. The proposed LC-MS/MS method was applied to the analysis of real honey samples.

A simplified modification to rapidly determine the residues of nitrofurans and their metabolites in aquatic animals by HPLC triple quadrupole mass spectrometry.

A simplified method is described for reducing the analysis time of nitrofurans (NFs) and nitrofuran metabolites (NFMs) in the aquatic animals. Most existing HPLC-MS/MS methods are intended only for NFMs and are based on their fast metabolic transformations. We optimized a method for simultaneously detecting major NFs and their metabolites, including nitrovin (NV) that imply use of an optimized buffer solution. The novel method was validated by six different aquatic animal matrices (loach, catfish, shrimp, lobster, scallop, and eel) spiked with the analytes at 0.5, 1.0, and 2.0 µg kg-1. Recovery rates and %RSDs (relative standard deviations) of 82-97% and 1-8% were observed for NFMs, respectively, with values of 70-96% and 1-8% obtained for furazolidone, furaltadone, nitrofurazone, nitrofurantoin, and NV, respectively. Linearity was observed in the 0.1-20 µg L-1 range, with correlation coefficients greater than 0.99 recorded for all compounds. The developed method is sensitive, accurate, easier to use, and faster than previous methods when applied to real samples. To the best of our knowledge, this is the first method that can simultaneously determine NFs and their metabolites, as well as NV, using a single-step extraction process.

Confirmation of five nitrofuran metabolites including nifursol metabolite in meat and aquaculture products by liquid chromatography-tandem mass spectrometry: Validation according to European Union Decision 2002/657/EC.

LC-MS/MS method for confirmation of nitrofuran metabolites in meat and aquaculture products, including the nifursol metabolite (DNSH), was developed. The nitrofuran metabolites investigated were as follows: 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), 1-aminohydantoine (AHD), semicarbazide (SEM) and 3,5-dinitrosalicylic acid hydrazide (DNSH). The sample preparation includes a washing step, allowing to analyze only the fraction of protein-bound residues. The final optimized recovery solvent for injection was found to be a mixture of ammonium acetate 2 mM/acetonitrile (60/40 ; v/v). Matrix effects and stability in biological matrix and standard solution for DNSH have been also carried out. Method performances were assessed using criteria of the Decision (EC) No 2002/657 and considering the proposed-for-adoption reference point for action (RPA) of 0.50 µg.kg-1 under Reg 1871/2019. Trueness ranged 86.5%-103.7% and precision ranged 2.0%-6.5% on intra-laboratory reproducibility conditions. Decision limit (CCα) ranged 0.028-0.182 µg.kg-1 and capability of detection limit (CCß) ranged 0.032-0.233 µg.kg-1.

Evaluation of ELISA kits for the screening of four nitrofuran metabolites in aquaculture products according to the European guideline for the validation of screening methods.

The administration of nitrofurans to livestock to treat or prevent animal diseases has been banned in the EU for the production of food of animal origin. The corresponding marker residues are tissue-related metabolites AMOZ, AHD, SEM, and AOZ. The MRPL (minimum required performance limit)/RPA (Reference point for action) was set at 1 µg kg-1 in the EU. Thus, all the laboratories involved in the control of nitrofuran metabolites must detect at least at this analytical limit of performance. The objectives of the work reported here were to evaluate the performance of ELISA kits from two different manufacturers (R-Biopharm, Germany; Europroxima, the Netherlands) for the individual screening of the four nitrofuran metabolites (AOZ, AMOZ; AHD; and SEM) in aquaculture products (fish, shrimps), and then to validate the kits according to the European Decision EC/2002/657 and to the European guideline for the validation of screening methods. The false positive rates were below 9 % for the kits from both manufacturers. The detection capabilities CCß determined were all below the current RPA (1 µg/kg). However, regarding the updated RPA at 0.5 µg/kg that shall apply in 2022, the AMOZ and SEM kits from R-Biopharm and the SEM kit from Europroxima will not be able to reach it.

Construction of a 18-Metal Neodymium(III) Nanoring with NIR Luminescent Sensing to Antibiotics.

One 18-metal Nd(III) nanoring, [Nd18(L1)8(HL2)2(OAc)20(MeOH)8(EtOH)6(H2O)4]·2(MeOH)·6(H2O) (1), was constructed by the use of a hexadentate Schiff base ligand. For 1, the near-infrared (NIR) luminescence of Nd(III) was detected under the excitation of absorption band at 371 nm. The study of luminescent sensing properties exhibits that, even with the existence of other antibiotics, this Nd(III) nanoring displays high sensitivity and selectivity to nitrofuran antibiotics (NFAs). The luminescence quenching constants and limits of detection of 1 to NFAs are found to be 1.4 × 104 to 3.5 × 104 M-1 and 0.9-2.2 µM, respectively.

One High-Nuclearity Cd(II)-Yb(III) Nanoring with Near-IR Luminescent Sensing to Antibiotics.

One 12-metal Cd(II)-Yb(III) nanoring, [Cd8Yb4L8(OAc)8]·4OH (1), with a size of 1.2 × 2.8 × 2.8 nm was obtained from a designed flexible salen-type ligand that has eight coordination sites (O and N atoms). The near-IR emission of Yb(III) at 983 nm was detected upon the excitation of ligand-central absorption at 386 nm. This Cd(II)-Yb(III) nanoring exhibits high sensitivity to nitrofuran antibiotics (NFAs) even in the presence of other antibiotics. The quenching constants and limits of detection of NFAs are 2.5 × 104-4.5 × 104 M-1 and 1.5-2.8 µM, respectively.

Photoresponsivity and antibiotic sensing properties of an entangled tris(pyridinium)-based metal-organic framework.

A two-dimensional Cd(ii) metal-organic framework (MOF) was constructed from a tris(pyridinium)-based hexacarboxylate zwitterionic ligand. The MOF shows a novel fashion of 2-fold 2D → 2D parallel entanglement. It is the entanglement that dictates close interlayer contacts between carboxylate (electron donor) and pyridinium (acceptor), which in turn impart the MOF with reversible photochromic properties through photoinduced electron transfer (PET). This is an extension of PET-based photochromism from bipyridinium to multipyridinium compounds. Thanks to the photoresponsive behaviour, the fluorescence of the MOF can be reversibly modulated or switched by photoirradiation. Besides, the fluorescence of the water-stable MOF in aqueous dispersion is very sensitive to nitrofuran antibiotics with high selectivity, and therefore the MOF is a good candidate of efficient and regenerable sensing material for determination of the antibiotics in water media.