Batch and Fed‐Batch Degradation of Enrofloxacin by the Fenton Process

Enrofloxacin is a synthetic second‐generation fluoroquinolone used as an antimicrobial agent exclusively in veterinary medicine. To simulate the treatment of wastewater contaminated by enrofloxacin, four‐day long fed‐batch runs were carried out according to the Fenton process with an enrofloxacin solution as model, to which hydrogen peroxide and ferrous ion were added twice a day. The residual enrofloxacin concentration was practically coincident to that detected at the end of the batch tests. Hydrogen peroxide was almost completely consumed after each feeding period, while the total organic carbon (TOC) concentration decreased gradually within three days, corresponding to a reduction > 58 %. From the third day on, the TOC falling rate was quite low. A yellow sludge settled due to the precipitation of both Fe(OH)₃ and a complex formed by ferric ion with adsorbed enrofloxacin and/or its oxidation products.     

产前饲喂模式下恩诺沙星在初产蛋中的残留规律及膳食暴露评估

目的 消费者长期食用残留恩诺沙星的禽蛋会造成耐药性、过敏反应以及肠道菌群紊乱。本试验旨在探讨蛋鸡产蛋前喂饲恩诺沙星在初产蛋中残留规律,评估其对鸡蛋安全性以及消费者健康的影响。方法 选取378只日龄为85天的海兰褐蛋鸡,根据给药时间分为14组,1.5 g/kg恩诺沙星粉剂,连续拌料喂药 5 d。从给药后生产第 1 枚鸡蛋开始连续采集鸡蛋8天,分析鸡蛋中恩诺沙星及其代谢产物环丙沙星残留量,采用每日允许摄入量对安全性进行评估。结果 初产蛋中恩诺沙星和环丙沙星含量均随着停药时间延长逐渐降低。给药5d,停药1天的初产蛋中恩诺沙星和环丙沙星含最高分别为959.725 mg/kg和62.263 mg/kg,停药7d后鸡蛋中环丙沙星含量低于检出限,痕量恩诺沙星代谢缓慢,停药24d后鸡蛋中恩诺沙星含量低于检出限。停药1d的初产蛋对儿童和成年人身体健康具有慢性危害风险。结论 为了保证禽蛋中无恩诺沙星残留建议至少需要在产蛋前29天用药,停药24天以上,以满足产品符合国家监管以及保证消费者健康的要求。     

盐酸恩诺沙星对蛋白核小球藻(Chlorella pyrenoidosa)的致毒效应研究

为探讨水产养殖中氟喹诺酮类药物残留对水生生物的毒性效应,研究了盐酸恩诺沙星对蛋白核小球藻(Chlorella pyrenoidosa)的急性毒性。结果显示,各药物质量浓度组对蛋白核小球藻的生长均有抑制作用,并且随药物处理质量浓度的增大,藻细胞的生长逐渐降低,显示出明显的剂量—效应关系。盐酸恩诺沙星对蛋白核小球藻的24,48,72,96h的EC50值分别为184.83,341.07,457.84,171.38μg/mL,叶绿素a和b的含量随着盐酸恩诺沙星处理质量浓度的增大呈现相同的变化趋势。     

恩诺沙星在余干乌鸡不同组织中的残留消除规律研究

目的 研究恩诺沙星可溶性粉在余干乌鸡各组织内的残留消除规律.方法 88只110 d龄健康余干乌鸡,随机分为11组,以0.75 g/L饮水连续给药5 d.停药后第0.16、1、3、5、7、9、20、30、40 d采集肌肉、肝脏、肾脏、皮脂样本,经液相色谱-串联质谱法测定组织中恩诺沙星和环丙沙星残留量,计算药物代谢半衰期,...     

Analyses of enrofloxacin, furazolidone and malachite green in fish products with surface-enhanced Raman spectroscopy

Illegal fish drugs used in aquaculture have raised serious concerns due to their negative effects on public health and environment. In this study, surface-enhanced Raman spectroscopy (SERS) was applied to analyze prohibited aquaculture drugs including enrofloxacin, furazolidone and malachite green (MG). Principal component analysis (PCA) and partial least squares (PLS) regression were used for spectral data analyses. For standard solutions, although no satisfied results were obtained for enrofloxacin, furazolidone and MG could be detected at 800 ng mL(-1) and 100 ng mL(-1), respectively. The R(2) of actual values vs. values predicted with PLS models for furazolidone and MG was 0.970 and 0.915, respectively. A clear segregation between furazolidone and MG was observed using PCA. Furazolidone and MG in tilapia fillets could be detected at 1 μg g(-1) and 200 ng g(-1), respectively, and their PLS models yielded R(2) of 0.922 and 0.843, respectively, showing potential for analyses of fish drugs with SERS.     

Latex bead and colloidal gold applied in a multiplex immunochromatographic assay for high-throughput detection of three classes of antibiotic residues in milk

Two rapid and sensitive high-throughput immunochromatographic assays were successfully developed for simultaneous determination of 12 sulfonamide, 18 quinolone and six tetracycline residues in milk. Under optimized conditions, residues from these three classes of antibiotics can be qualitatively and quantitatively determined on a single strip within 10 min. The detection limits were much lower than the maximum residue limits established by the European Union. Comparative evaluations of sensitivity, antibody consumption, coefficient of variation and user experience between these two immunochromatographic assays showed that latex beads have advantages over colloidal gold when employed as a label in the assay. Therefore, the latex bead-based high-throughput immunochromatographic assay has the best potential for on-site testing of a large number of samples as part of food safety applications.     

A composite prepared from covalent organic framework and gold nanoparticles for the electrochemical determination of enrofloxacin

A high conductivity composite based on covalent organic frameworks/gold nanoparticles (TAPB-PDA-COFs/AuNPs, TAPB: 3,5-tris(4-aminophenyl)benzene, PDA: p-phthalaldehyde) was prepared by a simple in-situ synthesized method and a novel electrochemical sensor based on TAPB-PDA-COFs/AuNPs was constructed for detection of Enrofloxacin (ENR). A variety of different characterization techniques including ultraviolet‐visible spectrophotometer (UV–vis), fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the TAPB-PDA-COFs/AuNPs. ENR was detected by square wave stripping voltammetry (SWV) according to the relationship between the ENR concentration and the oxidation peak current. The result showed that TAPB-PDA-COFs/AuNPs was synthesized successfully. The electrochemical sensor showed two linear ranges in the range of 0.05–10 μmol L^?1 and 10–120 μmol L^?1 with the limit of detection of 0.041 μmol L^?1 (S/N = 3). The good recoveries (96.7–102.2%) and low RSDs (0.9–6.4%) indicated the possibility of using this sensor for actual sample detection. Therefore, TAPB-PDA-COFs/AuNPs-based electrochemical sensor showed good performance in detecting ENR, and would be a potential candidate for the development of fluoroquinolones determination.     

Antibiotics and malachite green residues in farmed rainbow trout (Oncorhynchus mykiss) from the Iranian markets: A risk assessment

Antibiotic and malachite green residues in farmed rainbow trout muscles were determined by high-performance liquid chromatography for a food risk assessment. The surveillance was carried out on total of 120 rainbow trout fillets, all fishes were randomly sampled from 20 fish markets of Iran. All antibiotics were detected in the range of 0.42–1.20 μg/g for Oxytetracycline, 0.02–0.34 μg/g for Enrofloxacin, 0.21–2.61 μg/g for Florfenicol, and finally 0.02–0.89 μg/g for Malachite green. Our results showed that 99 (82.5%), 36 (30%), 56 (46.6%), and 70 (58.4%) samples contained detectable residues of Oxytetracycline, Enrofloxacin, and Florfenicol antibiotics, and Malachite green, respectively. Our results showed that fish farmers use these drugs in large scale. Further investigations are needed to prevent: the foodborne risk to consumers, the possible environmental contamination, and the antimicrobial resistances.     

Investigation of enrofloxacin residues in broiler tissues using ELISA and LC-MS/MS

This study investigated the efficiency of an enrofloxacin ELISA test kit to detect the presence of enrofloxacin residues in broiler tissues compared with LC-MS/MS. Broiler tissues from 72 samples consisting of 60 breast muscle, six pools of livers (500 g each) and six pools of kidneys (500 g each) were obtained from six different slaughterhouses. Breast muscle from 10 carcasses and pools of livers and kidneys from approximately 200 carcasses of the same flock were collected from each slaughterhouse. ELISA and HPLC were used to identify and quantify the contamination of the samples with enrofloxacin. A total of 72% of the analysed samples contained enrofloxacin residues detected by the ELISA and 22.2% were detected by LC-MS/MS. The mean values of enrofloxacin contamination found in chicken breast by ELISA and HPLC were 8.63 and 12.25 μg kg^–1, respectively. None of the samples exceeded the maximum limit of 100 μg kg^–1 by both methods set by the European Union as well as the Brazilian Agriculture Ministry. All positive samples for enrofloxacin residues detected by LC-MS/MS were also positive by ELISA. These data confirm the efficiency of the ELISA test, and suggest its use as a screening method for enrofloxacin residues in poultry tissues due to its quick results, low price and ease of applicability.     

Synthesis and characterization of molecularly imprinted polymers with metallic zinc center for enrofloxacin recognition

A molecularly imprinted polymer with a metallic center (MIPc) was prepared and characterized. The template molecule for MIPc was a complex [Zn(Aza-f)(Enr)]NO₃?H₂O, Com, based on the ligands: enrofloxacin (Enr) and azabis(oxazoline) functionalized with styrene. Com was characterized before preparing MIPc. Moreover, the polymer prepared via non-covalent (MIPe) was prepared using Enr as the template molecule while no template molecules were used to prepare the non-imprinted polymer (NIP).MIPc was characterized using different spectroscopic techniques. In addition, the polymer molecular recognition capacity was studied by using rebinding kinetic studies. The kinetics shows that MIPc reach the equilibrium before the MIPe and NIP and the amount of Enr adsorbed is approximately 5 times higher that MIPe and NIP.Scatchard plots analysis for NIP, MIPe and MIPc shows K_d = 0.4768, 0.020, 0.0067 (mmol L^?1) respectively. In comparison with the MIPe the binding affinity is nearly 100 times higher taking into account the high affinity sites. The selectivity of MIPc for Enr was higher than that for ofloxacin or flumequin, isotherms were fit to the Langmuir–Freundlich model, and the Enr showed a value of K_o = 21.38 mM^?1, while the ofloxacin had a value of 2.2 × 10^?8 mM^?1 and the flumequin of 1.6 × 10^?5 mM^?1.