Anuradha Singh

A high-resolution mass spectrometry (HRMS) method was developed and optimized for quantitative and confirmatory analysis of the nitrofurazone (NFZ) cyano metabolite in shrimp. Extraction with 80% acetonitrile: buffer, salting out, and solid phase cartridge cleanup resulted in 87-112% recovery, <10% precision, and good sensitivity with 0.02 ppb limit of quantitation. Current monitoring of unauthorized NFZ use in aquaculture relies upon semicarbazide (SEM) metabolite detection; however, the natural occurrence of SEM in some crustaceans has raised interest for an alternative biomarker. The developed method was used to investigate the suitability of cyano metabolite as an alternate biomarker for unauthorized use of NFZ. In NFZ-incurred shrimp, the cyano metabolite depleted rapidly, with no detection after 6 days, while SEM was detected for at least 20 days. The short-lived stability of cyano metabolite limits its potential for nitrofurazone surveillance in shrimp. However, the method may be adequate for NFZ surveillance in other food animal matrices.

Polyethylene terephthalate (PET) is one of the most extensively used plastics in daily life. Due to its prevalent use, it is ubiquitous in the environment and a significant contributor to plastic pollution. Continuous exposure to photochemical, thermal, biological, and mechanical processes makes PET susceptible to slow degradation and the production of microsized and/or nanosized particles known as PET microplastic/nanoplastic (MP/NP). MP/NP are widely detected in the environment, including in drinking water and human food; consequently, knowledge gaps on the impacts of MP/NP in human food sources have gained global attention. A large knowledge gap is the bioaccumulation and fate of PET MP/NP in food animals. The application of carbon‐14 labeled PET NP in food animals would provide a relatively straightforward approach to understanding the degree of PET absorption and its tissue distribution after absorption. Here, a simple, fast, and efficient synthetic method is described to produce [¹⁴C]‐PET NP. The method comprises the polycondensation of terephthaloyl chloride and readily accessible [¹⁴C]‐ethylene glycol followed by nanoprecipitation. The synthesized [¹⁴C]‐PET and [¹⁴C]‐PET NP were characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering spectroscopy, thermogravimetric analyzer (TGA), and UV‐Vis spectroscopy.

Nitrofurazone (NFZ), a synthetic antibiotic, is banned from use in food animals because of its potential carcinogenicity and mutagenicity. Regulatory agencies regularly surveil illegal use of NFZ in animal-derived products by measuring a marker metabolite, semicarbazide (SEM). However, SEM is not specific for NFZ exposure, and its detection has proven to return false positive results in unexposed animals. Therefore, the identification of a NFZ-specific marker is a pressing need for detecting illicit NFZ use. To this end, disposition and depletion studies in broiler chickens were performed using ¹⁴C-NFZ test articles containing radiocarbon at the furaldehyde carbon (NFZ-A) or the carbonyl carbon of SEM (NFZ-B). Birds were fed complete rations containing [¹⁴C]-NFZ-A (n = 12, Group A) or ¹⁴C-NFZ-B (n = 12, Group B) at 5 mg NFZ/kg feed for 7 consecutive days. Control birds (n = 6) were fed NFZ-free feed. Birds were euthanized on withdrawal days (WD) 0, 4, 7, and 14. Total radioactive residues in plasma, liver, kidney, muscle, gizzard, lung, and heart were determined by oxidation, followed by liquid scintillation counting. At WD 0, the kidney was the major depot for total radioactive residues followed by the liver. Depletion rates of radioactive residues in tissues were not different (P > 0.20) between the NFZ-A and NFZ-B treated groups, suggesting that the SEM moiety remained intact during biotransformation of both nitrofurazone test articles. Estimated half-life of radioactive residues was longer in muscle than that in the liver. About 70% or higher of NFZ-related residues remained unextractable and bound to tissues, regardless of the withdrawal day. Major portions of NFZ-residues were covalently bound to protein, with smaller portions bound to DNA and RNA fractions.

Post-harvest storage loss in sugar beets due to root rot and respiration can cause >20% sugar loss. Breeding strategies focused on factors contributing to improved post-harvest storage quality are of great importance to prevent losses. Using 16S rRNA and ITS sequencing and sugar beet mutational breeding lines with high disease resistance (R), along with a susceptible (S) commercial cultivar, the role of root microbiome and metabolome in storage performance was investigated. The R lines in general showed higher abundances of bacterial phyla, Patescibacteria at the M time point, and Cyanobacteria and Desulfobacterota at the L time point. Amongst fungal phyla, Basidiomycota (including Athelia) and Ascomycota were predominant in diseased samples. Linear discriminant analysis Effect Size (LEfSe) identified bacterial taxa such as Micrococcales, Micrococcaceae, Bacilli, Glutamicibacter, Nesterenkonia, and Paenarthrobacter as putative biomarkers associated with resistance in the R lines. Further functional enrichment analysis showed a higher abundance of bacteria, such as those related to the super pathway of pyrimidine deoxyribonucleoside degradation, L-tryptophan biosynthesis at M and L, and fungi, such as those associated with the biosynthesis of L-iditol 2-dehydrogenase at L in the R lines. Metabolome analysis of the roots revealed higher enrichment of pathways associated with arginine, proline, alanine, aspartate, and glutamate metabolism at M, in addition to beta-alanine and butanoate metabolism at L in the R lines. Correlation analysis between the microbiome and metabolites indicated that the root’s biochemical composition, such as the presence of nitrogen-containing secondary metabolites, may regulate relative abundances of key microbial candidates contributing to better post-harvest storage.

Nitrofurazone usage in food‐producing animals is prohibited in most countries, including the United States. Regulatory agencies regularly monitor its use in domestic, export/import animals' food products by measuring the semicarbazide (SEM) metabolite as a biomarker of nitrofurazone exposure. However, the use of SEM is controversial because it is also produced in food naturally and thus gives false positive results. A cyano‐metabolite, 4‐cyano‐2‐oxobutyraldehyde semicarbazone (COBS), is proposed as an alternate specific marker of nitrofurazone to distinguish nitrofurazone from treated or untreated animals. A synthetic method was developed to produce COBS via metallic hydrogenation of nitrofurazone. The product was isolated and characterized by one‐ and two‐dimensional nuclear magnetic spectroscopy (NMR) experiments, Fourier‐transform infrared spectroscopy (FT‐IR), and mass spectrometry. The developed synthetic procedure was further extended to synthesize isotopically labeled 4‐[¹³C]‐cyano‐2‐oxo‐ [2, 3, 4‐¹³C₃]‐butyraldehyde semicarbazone. Labeled COBS is useful as an internal standard for its quantification in food‐producing animals. Thus, the developed method provides a possibility for its commercial synthesis to procure COBS. This is the first synthesis of the alternate specific marker metabolite of nitrofurazone for possible usage in regulatory analysis to solve a real‐world problem.

The veterinary drug nitrofurazone (5‐nitro‐2‐furaldehyde semicarbazone) exhibits excellent antimicrobial properties but its application in food‐producing animals is prohibited. The illegal use of nitrofurazone is regularly monitored by food regulatory agencies. Currently, semicarbazide (SEM) is used as a marker of nitrofurazone exposure. However, the use of SEM as a marker of nitrofurazone is under scrutiny after evidence of a high incidence of false positive tests. To overcome the current dilemma, it is necessary to identify a nitrofurazone‐specific marker analyte which requires conducting nitrofurazone metabolism studies in food‐producing animals. The use of carbon‐14 labeled nitrofurazone would facilitate metabolism studies and structural elucidation of nitrofurazone metabolites of possible utility as a marker compound. In the present work, a synthetic method is described to procure radiolabeled nitrofurazone that incorporates ¹⁴C‐ carbon at the semicarbazide moiety. The method incorporates ¹⁴C‐carbon via employing readily available and more economically affordable [¹⁴C]‐urea compared with [¹⁴C]‐semicarbazide. To the best of our knowledge, there is no report on the synthesis of 5‐nitro‐2‐furaldehyde [¹⁴C]‐semicarbazone from ¹⁴C‐urea. The developed method involves monoamination of [¹⁴C]‐urea followed by a condensation reaction with 5‐nitro‐2‐furaldehyde to produce 5‐nitro‐2‐furaldehyde [¹⁴C]‐semicarbazone in 85% yield with greater than 98% radiochemical purity.

Polybrominated diphenyl ethers (PBDEs) levels in environmental matrices have generally declined following their phaseout as flame retardants. The objective of this study was to determine the absorp...

Despite the exponential growth of the field of photocatalysis, for reasons that are not entirely clear, these precious photocatalysts are often used in the literature at loadings that exceed their maximum solubility. On an industrial scale, the quantity of any precious-metal catalyst can be a substantial financial burden or a sourcing issue, not to mention concerns as to the ecological and earth abundance of these catalysts. We believe that inattention to solubility has made these reactions appear less efficient than they actually are because much of the photocatalyst remains undissolved. Therefore, the maximum solubilities of iridium- and ruthenium-centered photocatalysts in industrially relevant solvents have been systematically identified. Furthermore, a literature photocatalytic reaction that our results suggested was beyond the maximum solubility has been revisited with interesting results.

Metabolism, environmental fate, and low concentration food residue studies would be facilitated by the use of radiolabeled test articles that can be readily quantified within complex matrices. However, radiochemical approaches for such studies require high specific activities to allow analytical detection of correspondingly low masses of test article. The synthesis of high specific activity (>50 μCi/μmol) [¹⁴C]‐radiolabeled phenylbutazone presents a challenge using existing methodology, mainly due to the low solvent volumes required and vigorous refluxing needed to close the pyrazolidinedione ring. Herein, we report on the significant modification of an existing method that allows the synthesis of low masses of high specific activity (>50 μCi/μmol) [¹⁴C]‐phenylbutazone under mild conditions with simple purification and high yield. The closure of the pyrazolidinedione ring of 1,2‐diphenyl‐3,5‐pyrazolidinedione was accomplished as a first step with unlabeled 1,2‐diphenylhydrazine and diethyl malonate in 32% yield under gram‐scale conditions, which avoided the challenges of low solvent use and vigorous refluxing. Low mass of high specific activity n‐[1‐¹⁴C]‐butyl bromide was then added via a nucleophilic substitution reaction as a final step. Yields ranged from 65% to 92% during multiple synthetic attempts with unlabeled butyl bromide and were greatly influenced by reaction stoichiometry and the selection of base.