Thermal degradation of chloramphenicol in model solutions, spiked tissues and incurred samples

Effect of Cooking Methods on Amphenicols and Metabolites Residues in Livestock and Poultry Meat Spiked Tissues

Foods of animal origin, as nutritional supplements, are usually consumed after cooking, but residues of amphenicols in fresh raw meat threaten human health. Therefore, this study was designed to evaluate the effects of boiling, deep-frying and microwave processing under different time conditions on the residue levels of amphenicols and metabolites in livestock and poultry meat. Antibiotic-free pork, beef, lamb and chicken samples were spiked with chloramphenicol (CAP), thiamphenicol (TAP), florfenicol (FF) and florfenicol amine (FFA) standard solutions and made into homogeneous meat blocks. These positive mock meat blocks were processed using three different cooking methods, and the analyses were performed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The results showed that cooking methods, time and food matrices were the main factors influencing the changes in amphenicols and metabolites residues in livestock and poultry meat. With the increase in cooking time, boiling processing was the most effective in reducing the four drug residues in livestock and poultry meat matrices, followed by deep-frying, while microwaving caused an increase in drug residue concentrations. Although boiling and frying processes are effective strategies to reduce amphenicols and metabolites residues in meat, it cannot be assumed that these residues can always decrease to levels that are safe for consumer health, especially when the drug residue concentrations in raw meat are above the maximum residue limits (MRLs). Therefore, it is not reliable to remove residues of amphenicols and metabolites from food by cooking. The solution to the food safety problem of veterinary drug residues must start from the breeding source and accelerate the implementation of antibiotic reduction, antibiotic substitution and antibiotic-free farming.

Application of Nontarget Analysis and High-Resolution Mass Spectrometry for the Identification of Thermal Transformation Products of Oxytetracycline in Pacific White Shrimp

ABSTRACT

Oxytetracycline (OTC) is an antibiotic authorized for use in aquaculture; it is often detected in seafood products, especially shrimp. Previous studies investigating the fate of OTC in shrimp tissues after cooking were limited to quantification of parent compound residues and did not describe any potential transformation products formed. Hence, the main objective of this study was to apply a nontarget analysis workflow to study the fate of OTC in shrimp muscle. Furthermore, "water" and "spiked" models were evaluated for their suitability to track the transformation of OTC in incurred muscle and to determine whether the matrix plays a role in the transformation pathway. First, four different extraction methods were compared for the determination of OTC in muscle. Second, raw and cooked samples were then extracted using a suitable method (acidified water-methanol-acetonitrile, with cleanup of samples achieved using freezing) and were analyzed by high-performance liquid chromatography quadrupole time-of-flight mass spectrometry. OTC levels were reduced by 75 and 87% in muscle and water, respectively. Identification of thermal transformation products was limited to formula generation, but results showed that different compounds were identified in spiked and incurred muscle.

HIGHLIGHTS

Rapid removal of chloramphenicol via the synergy of Geobacter and metal oxide nanoparticles

The wide use of chloramphenicol and its residues in the environments are an increasing threat to human beings. Electroactive microorganisms were proven with the ability of biodegradation of chloramphenicol, but the removal rate and efficiency need to be improved. In this study, a model electricigens, Geobacter metallireducens, was supplied with and Fe₃O₄ and MnO₂ nanoparticles. Five times higher chloramphenicol removal rate (0.71 d^-1) and two times higher chloramphenicol removal efficiency (100%) was achieved. Fe₃O₄ and MnO₂ nanoparticles highly increased the current density and NADH-quinone oxidoreductase expression. Fe₃O₄ nanoparticles enhanced the expression of alcohol dehydrogenase and c-type cytochrome, while MnO₂ nanoparticles increased the transcription of pyruvate dehydrogenase and Type IV pili assembly genes. Chloramphenicol was reduced to a type of dichlorination reducing product named CPD3 which is a benzene ring containing compound. Collectively, Fe₃O₄ and MnO₂ nanoparticles increased the chloramphenicol removal capacity in MFCs by enhancing electron transfer efficiency. This study provides new enhancing strategies for the bioremediation of chloramphenicol in the environments.

Application of non-target analysis to study the thermal transformation of malachite and leucomalachite green in brook trout and shrimp

The fate of malachite green and its main metabolite leucomalachite green during thermal treatment was examined in seafood (brook trout and white shrimp) using non-target analysis. Samples were extracted using QuEChERS and analyzed using liquid chromatography coupled with quadruple time of flight mass spectrometry. Malachite green levels were reduced in meat during boiling (∼40%), microwaving (64%), and canning (96%). Only microwaving was successful in significantly decreasing leucomalachite green levels in brook trout. The reduction percentages of the two target analytes were not significantly different in shrimp (mean fat content = 0.8 ± 0.3%) and in brook trout (mean fat content = 3.5 ± 1.7%), suggesting that a higher fat content may not affect the reduction of the more lipophilic leucomalachite green in these two matrices. Three transformation products were tentatively identified in the cooked tissues, resulting from the cleavage of the conjugated structure or through demethylation. Further research is needed to determine possible adverse health effects. The findings of this study show how non-target analysis can complement targeted methodologies in identifying and evaluating risks to human health.

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Non-target analysis was applied to study the fate of malachite/leucomalachite green.

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Thermal processing significantly reduced malachite green in seafood by up to 96%.

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Leucomalachite green levels were significantly reduced only after microwaving.

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Three transformation products were tentatively identified.

Antibacterial, thermal decomposition and in vitro time release studies of chloramphenicol from novel PLA and PVA nanofiber mats

The present investigation is the first report containing design and synthesis of novel calixarene derivatives (6-8) and their inclusion complexes (IC6-IC8) with Chloramphenicol (CAM). After synthesis, the antibiotic CAM, calixarene derivatives (6-8) and their inclusion complexes (IC6-IC8) were successfully incorporated into biodegradable PVA and/or PLA nanofiber skeleton by electrospinning. The obtained electrospun nanofibers were tested and compared for inhibition of bacterial growth towards multiple bacterial species (Escherichia coli, and Bacillus subtilis). Moreover, we evaluated thermal decomposition and release profile of CAM by spectrophotometric methods. The results suggested that CAM can be successfully encapsulated in nanofiber webs by inclusion complexation, and these fibers could be used as a part of new controlled release packaging system for food preservation.

Non-targeted study of the thermal degradation of tylosin in honey, water and water:honey mixtures

Tylosin A is a macrolide antibiotic used in beekeeping. The aim of the study was to characterise the behaviour of tylosin A in honey after heating and during storage, and to identify its degradation products using a non-targeted approach. In addition, the possibility of a semi-quantification of tylosin B using tylosin A was assessed as a case study for the semi-quantification of degradation products using the parent compounds. The results showed significant degradation of tylosin A in aqueous solution (~96%) as well as in spiked and incurred honey dissolved in water (~50% and ~29%, respectively) after heating at 100°C for 90 min. However, at a lower heating temperature of 70°C, degradation was only observed in water (~31%). When stored at room temperature (27°C) for one year, tylosin A degraded significantly (~47%) in an incurred honey sample. Tylosin B, the only reported degradation product of tylosin A in honey so far, increased significantly in aqueous solution under all treatments, but it only increased in spiked water-honey mixture after heating at 100°C. Two new degradation products, namely 5-O-mycaminosyltylonolide (OMT) and lactenocin, were tentatively identified in water and spiked honey after heating at 100°C. The results of the present study reinforce the conclusion that relying only on the water model or spiked food matrix is not sufficient to understand the thermal degradation of antibiotics in food matrices. Finally, a semi-quantification of tylosin B with a relative error of 20% in an incurred honey sample was possible using the response factor of tylosin A, its parent compound. The results of this study prove that a semi-quantification using the parent compound to quantify its degradation compound can provide satisfactory results, but this will be analyte-dependent.

Multiple signal amplification chemiluminescence immunoassay for chloramphenicol using functionalized SiO2 nanoparticles as probes and resin beads as carriers

A novel, rapid and convenient competitive immunoassay for ultrasensitive detection of chloramphenicol residues in shrimp and honey was established combined with flow injection chemiluminescence. The carboxylic resin beads were used as solid phase carriers to load with more coating antigen due to their larger specific surface area and good biocompatibility. The surface of the silica dioxide nanoparticles was modified with aldehyde group to combine with more horseradish peroxidase and the chloramphenicol antibody. There was a competitive process between the chloramphenicol in solution and the immobilized coating antigen to combine with the limited binding site of antibody to form the immunocomplex. Silica dioxide nanoparticles played an important role in enhancing chemiluminescence signal, because the horseradish peroxidase on SiO₂ effectively catalyzed the system of luminol-PIP-H₂O₂. Under optimal conditions, the chemiluminescence intensity decreased linearly with the logarithm of the chloramphenicol concentration in the range of 0.0001 to 100 ng mL^-1 and the detection limit (3σ) was 0.033 pg mL^-1. This immunosensor demonstrated acceptable stability, high specificity and reproducibility. The horseradish peroxidase-silica dioxide nanoparticle-chloramphenicol antibody complex successfully prepared in this article was firstly applied to the detection of chloramphenicol, and had extremely important meanings for the application of nanoparticles and enzymatic catalysis in the field of chemiluminescence.

Development of a liquid chromatography-quadrupole-time-of-flight-mass spectrometry based method for the targeted and suspect screening of contaminants in the pearl oyster Pinctada imbricata radiata

A rapid method based on solvent extraction followed by direct injection in liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOF-MS) was developed for the targeted and suspect screening of contaminants in the soft tissues of the pearl oyster Pinctada imbricata radiata. The quantification method was first validated for the targeted analysis of 21 contaminants including some pharmaceutically active compounds, with the relative recoveries ranging from 88 to 123%, and method detection limits generally below 1 ng g^-1 on the wet weight (ww) basis. This targeted analysis method was then applied to oyster samples collected around the Qatari coast between 2017/2018, and none of the 21 compounds were detected in these samples. The post-acquisition data treatment based on the accurate mass measurement in both full MS scan and All Ions MS/MS was further used for mining other contaminants in oyster extracts, as well as 21 targeted compounds spiked in oyster extracts (suspect screening). The 21 spiked compounds were identified successfully and the estimated limit of identification for the individual 21 compounds ranged from 0.5 to 117 ng g^-1 ww of oyster tissues. A phthalate, di(2-ethylhexyl) phthalate (DEHP) was identified to be present in oyster extracts from 2018 batches, at a concentration level significantly higher than that in procedure blanks. These results confirmed that high resolution MS data obtained using the targeted method can be exploited through suspect screening workflows to identify contaminants in the tissues of bioindicator mollusks. However, a number of false identifications could be obtained and future work will be on improving the success rate of the correct identifications using this workflow.

Degradation of ticarcillin by subcritical water oxidation method: Application of response surface methodology and artificial neural network modeling

This study was performed to investigate the mineralization of ticarcillin in the artificially prepared aqueous solution presenting ticarcillin contaminated waters, which constitute a serious problem for human health. 81.99% of total organic carbon removal, 79.65% of chemical oxygen demand removal, and 94.35% of ticarcillin removal were achieved by using eco-friendly, time-saving, powerful and easy-applying, subcritical water oxidation method in the presence of a safe-to-use oxidizing agent, hydrogen peroxide. Central composite design, which belongs to the response surface methodology, was applied to design the degradation experiments, to optimize the methods, to evaluate the effects of the system variables, namely, temperature, hydrogen peroxide concentration, and treatment time, on the responses. In addition, theoretical equations were proposed in each removal processes. ANOVA tests were utilized to evaluate the reliability of the performed models. F values of 245.79, 88.74, and 48.22 were found for total organic carbon removal, chemical oxygen demand removal, and ticarcillin removal, respectively. Moreover, artificial neural network modeling was applied to estimate the response in each case and its prediction and optimizing performance was statistically examined and compared to the performance of central composite design.