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Olaquindox, oxytetracycline and chlorotetracycline were widely used in feed as antibiotics and growth promoter to improve feed conversion efficiency and increase the rate of weight gain for animals. However, the use of these antibiotics in feed was gradually prohibited because of concerns about contamination and resistance in animals. A quantitative and confirmatory method for determining the presence of olaquindox, oxytetracycline and chlorotetracycline in feed by high performance liquid chromatography equipped with ultraviolet detector in series with fluorescence detector (HPLC-UVD-FLD) was developed, optimized, and validated in three different matrices (compound, concentrated and premix feed). The analytes extraction was performed with a mixture of acetonitrile and 0.1 mol/L ethylenediamine tetraacetic acid disodium-Mcllvaine buffer (1:4, v/v) by one step sample preparation procedure. The validated method presented a broad linear range and good linearity with weighted least square method. The decision limit of the analytes ranged from 0.61 to 0.77 mg/kg for olaquindox, 0.90 to 1.2 mg/kg for oxytetracycline and 1.3 to 2.0 mg/kg for chlorotetracycline. The average recovery values found in intermediate precision conditions were ranged from 88.0 to 99.7% for olaquindox with RSD lower than 11.1%, from 84.4 to 99.0% for oxytetracycline with RSD lower than 9.6%, from 83.8 to 97.5% for chlorotetracycline with RSD lower than 10.0%. By Youden test and bottom-up method, the method was proved to be sufficiently robust and had a small uncertainty for different concentration levels. The developed method was successfully utilized for commercial feed samples to monitor complex cross contamination and residue conditions. Online synchronous derivation and separation using ultraviolet detector in series with fluorescence detector can effectively prevent false positive of chlorotetracycline in feed caused by vegetable meal. Since olaquindox, oxytetracycline and chlorotetracycline are widely used in feed, the developed method provide an important and analytical tool for the simultaneous identification and quantification of them in feed to monitor its risk of cross contamination and excessive content., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Water pollution arising from pharmaceuticals has raised great concerns about the potential risks for biosphere and human health. However, rapid and efficient removal of pharmaceutical contaminants from water remains challenging. Wood sawdust, a byproduct of the wood-processing industry, is an abundant, cost-effective, and sustainable material with a unique hierarchically porous microstructure. These features make wood sawdust quite interesting as a filtration material. Here, we report a novel cross-flow filtration composite based on β-cyclodextrin-polymer-functionalized wood sawdust (β-CD/WS) in which the pharmaceutical contaminant water flows through the sawn-off vessel channels and the micropores on the surface of the cell walls, generating the turbulence. Such water flow characteristics ensure full contact between pharmaceutical pollutants and β-CD grafted on the cellulose backbone of wood sawdust, thereby enhancing the water treatment efficiency. Consequently, the β-CD/WS filter device shows a high removal efficiency of over 97.5% within 90 s for various pharmaceutical contaminants including propranolol, amitriptyline, chlortetracycline, diclofenac, and levofloxacin, and a high saturation uptake capacity of 170, 156, 257, 159, and 185 mg g -1 , respectively. The high-performance wood-sawdust-based cross-flow filtration opens new avenues for solving the global water pollution issues, especially those caused by pharmaceutical contaminants.

Antibiotics are active substances frequently used to treat and prevent diseases in animal husbandry, especially in swine and poultry farms. The use of manure as a fertilizer may lead to the dispersion of antibiotic residue into the environment and consequently the development of antibiotic-resistant bacteria. Most pharmaceutical active ingredients are excreted after administration, in some cases up to 90% of the consumed dose can be found in the feces and/or urine as parent compound. Therefore, due to antibiotic metabolism their residues can be easily detected in manure. This article describes a method for simultaneous analysis of ciprofloxacin, chlortetracycline, doxycycline, enrofloxacin, lincomycin, oxytetracycline, tetracycline, tiamulin, trimethoprim and tylosin in feces, liquid manure and digestate. Antibiotics were extracted from the different matrices with McIlvaine-Na 2 EDTA buffer solution and the extract was purified by the use two techniques: d-SPE and SPE (Strata-X-CW cartridges) and final eluent was analyzed by LC-MS and LC-MS/MS. The European Commission Decision 2002/657/EC was followed to conduct the validation of the method. Recoveries obtained from spiked pig and poultry feces and liquid manures samples ranged from 63% to 93% depending on analytes. The analysis of 70 samples (feces, liquid manure and digestate) revealed that 18 samples were positive for the presence of doxycycline, oxytetracycline, tetracycline, chlortetracycline, enrofloxacin, tiamulin and lincomycin. The results obtained in the presented study demonstrated that animal feces can be used as a non-invasive method detection antibiotic usage in animal production.

Natural clay sediments were collected from ten different localities in Saudi Arabia (S-1 from eastern, S-2 to S-4 from middle and S-5 to S-10 from western regions), characterized and evaluated for their efficiency towards chlortetracycline (CTC) removal from aqueous solutions. Sediment S-4 exhibited highest surface area (288.5 m 2  g -1 ), followed by S-5, S-9, and S-1 (252.1, 249.6, and 110.4 m 2  g -1 , respectively). Sediments S-5, S-9, S-2, and S-4 showed the highest cation exchange capacities (CEC) (62.33, 56.54, 52.72, and 46.85 cmol kg -1 , respectively). The pH range of 3.5-5.5 was optimum for the highest CTC removal. Freundlich model was best fitted to CTC sorption data (R 2  = 0.96-0.99), followed by Dubinin-Radushkevich model (R 2  = 0.89-0.97). The sediments S-4, S-5, and S-9 exhibited the highest CTC removal efficiency (98.80-99.05%), which could be due to higher smectite and kaolinite contents, CEC, surface area and layered structure. Post-sorption XRD patterns shown new peaks and peak shifts confirming the sorption of CTC. Electrostatic interactions, interlayer sorption and H-π bonding were the potential CTC sorption mechanisms. Therefore, natural clay sediments with high sorption capacities could efficiently remove CTC from contaminated aqueous media., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Nano micro-electrolysis materials (nMETs) have been used to degrade refractory pollutants in batch experiments. The reasonable formation mechanism of nMETs was given through DMXY digital biomicroscopy. Based on the kinetic data of Chlortetracycline (CTC) removal by nMETs in batch experiments, combined with the binomial distribution equation of CTC reduction by nano materials an experimental-scale fluidized bed (ESFB) was designed. The effects of CTC removal performance, pH and iron ion concentration were investigated. Under pure CTC solution environment, the experimental data showed that the average removal rates of CTC by nMET and nano micro-electrolysis material with loading copper (Cu-nMET) are 90.0% and 95.7% in ESFB, respectively. In the presence of nitrate, although the consumption of two kinds of nano-materials increased, their removal efficiencies of pollutants have 2.2%, 0.2% increase compared with the nitrate-free ESFB. At the same time, the CTC degradation pathway and the enhanced removal mechanism by Cu-nMET was proposed. Through microelectrolysis reaction, complexation reaction and the active substances produced, the intermediate products can be degraded completely to NH 4 + , CO 2 , H 2 O and so on. This study aims to provide a theoretical basis for the environmental application of nMETs., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This paper describes a modification method of Na-montmorillonite (Na-Mt) with carboxymethyl-chitosan (CMC). The as-prepared samples were analyzed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface analyzer and thermogravimetric analysis (TGA). Two common tetracycline antibiotics, tetracycline (TET) and chlortetracycline (CTC), were selected as the represented pollutants and adsorbed by CMC-Mt under different experimental conditions. The intercalation of CMC obviously amplified the basal spacing of the interlayers confirmed by XRD measurements and improved the adsorption capacities of montmorillonite to some degree. The results showed that the tetracycline antibiotic sorption onto CMC-Mt was mainly dependent on pH and was not affected by temperature. Besides, the removal of TET and CTC rapidly attained an equilibrium within 2 h of contact time. The kinetic data of adsorption was determined by first-order, second-order kinetics and intraparticle diffusion models. The kinetic study indicates that the TET and CTC adsorption processes obeyed the second-order kinetics. The Freundlich isotherm study was in agreement with the practical data, suggesting a heterogeneous sorption process. Furthermore, the thermodynamic studies revealed that the removal process was more spontaneous at a lower temperature, implying it an exothermic reaction. The synthesized adsorbent CMC-Mt can be widely used in the treatment of wastewater., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The presence of tetracycline antibiotics (TCS) in the water and wastewater has raised growing concern due to its potential environmental impacts; thus, their removal is of high importance. In this study, a novel aluminum-based MOF/graphite oxide (Al-MOF/GO) granule was prepared as an adsorbent for the removal of TCS including oxytetracycline (OTC) and chlortetracycline (CTC). The adsorbent was characterized via XRD, FTIR, BET, SEM, and XPS methods. The granules exhibited similar crystal structure and some new mesopores appearing compared to the parent Al-MOF/GO powder. In addition, the adsorption behavior of OTC and CTC on samples was explored as a function of initial concentration, contact time, pH, and ionic strength by means of batch experiments. The adsorption capacity reached to 224.60 and 240.13 mg·L -1 for OTC and CTC, at C 0  = 60 mg·L -1 as well as ambient temperature respectively. Moreover, the adsorption process of OTC and CTC on Al-MOF/GO samples can be better delineated by pseudo-second-order kinetics and Freundlich isotherm models. Besides, the adsorption mechanism over Al-MOF/GO granules was proposed, which could be ascribed to π-π interaction, cation-π bonding, and hydrogen bond. Finally, the great water stability, separation performance, and regeneration efficiency of these novel granules indicated their potential application in the OTC and CTC removals from aqueous solution.

This study investigates the removal of chlortetracycline (CTC) antibiotic using sulfate radical-based oxidation process. Sodium persulfate (PS) was used as a source to generate sulfate radicals by homogeneous (Fe 2+ ) and heterogeneous (zero valent iron, ZVI) iron as a catalyst. Increased EDTA concentration was used to break the CTC-Fe metal complexes during CTC estimation. The influence of various parameters, such as PS concentration, iron (Fe 2+ and ZVI) concentration, PS/iron molar ratio, and pH were studied and optimum conditions were reported. CTC removal was increased with increasing concentration of PS and iron at an equal molar ratio of PS/Fe 2+ and PS/ZVI processes. PS/Fe 2+ and PS/ZVI oxidation processes at 1:2 (500 μM PS and 1000 μM) molar ratio showed 76% and 94% of 1 μM CTC removal in 2 h. Further increased molar ratio 1:2 onwards, PS/Fe 2+ process showed a slight increase in CTC degradation whereas in PS/ZVI process showed similar degradation to 1:2 (PS/Fe) ratio at constant PS 500 μM concentration. Slower activation of persulfate which indirectly indicates the slower generation of sulfate radicals in PS/ZVI process showed higher degradation efficiency of CTC. The detected transformation products and their estrogenicity results stated that sulfate radicals seem to be efficient in forming stable and non-toxic end products., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Aerobic composting experiments were conducted under three different temperatures (55℃, 35℃, and non-temperature-controlled) with human feces and sawdust as the compost material and bulky matrix respectively. Attention was paid to the effects of temperature on the removal of four typical antibiotics (tetracycline, chlortetracycline, sulfadiazine, and ciprofloxacin) during human feces aerobic composting. Furthermore, three specific experiments were conducted to identify the possible antibiotic degradation mechanisms in aqueous solution and during composting with moist sterile sawdust but without feces and composting with feces and moist sterile sawdust. The most effective removal of the four antibiotics was achieved through thermophilic composting (55℃). At 55℃, more than 90% of all the antibiotics were removed. The degradation of tetracycline and chlortetracycline was more temperature-dependent than that of sulfadiazine and ciprofloxacin. Moreover, tetracycline and chlortetracycline removal was primarily through hydrolysis in moist environments. However, sulfadiazine and ciprofloxacin removal was mainly attributed to adsorption by sawdust particles. The contribution of microbial action to antibiotic degradation was insignificant for all the antibiotics except ciprofloxacin. Up to 20% of this antibiotic was degraded by microbial action.

Tetracyclines are important antimicrobial drugs for poultry farming that are actively excreted via feces and urine. Droppings are one of the main components in broiler bedding, which is commonly used as an organic fertilizer. Therefore, bedding becomes an unintended carrier of antimicrobial residues into the environment and may pose a highly significant threat to public health. For this depletion study, 60 broiler chickens were treated with 20% chlortetracycline (CTC) under therapeutic conditions. Concentrations of CTC and 4-epi-CTC were then determined in their droppings. Additionally, this work also aimed to detect the antimicrobial activity of these droppings and the phenotypic susceptibility to tetracycline in E. coli isolates, as well as the presence of tet(A) , tet(B) , and tet(G) resistance genes. CTC and 4-epi-CTC concentrations that were found ranged from 179.5 to 665.8 µg/kg. Based on these data, the depletion time for chicken droppings was calculated and set at 69 days. All samples presented antimicrobial activity, and a resistance to tetracyclines was found in bacterial strains that were isolated from these samples. Resistance genes tet(A) and tet(B) were also found in these samples.

A novel magnetic chitosan-g-poly(2-acrylamide-2-methylpropanesulfonic acid) (CTS-g-AMPS) porous adsorbent was prepared by grafting the AMPS onto the CTS in the Fe 3 O 4 stabilized Pickering high internal phase emulsions (Pickering-HIPEs) and used for the adsorptive removal of the antibiotics tetracycline (TC) and chlorotetracycline (CTC). The results of the structure characterization showed that porous structure of the adsorbent can be tuned easily by altering amount of Fe 3 O 4 -MNPs-M and the electrostatic attraction of between SO 3 - and CTC, TC was the main adsorption driving force. The adsorption capacities of the adsorbent for TC and CTC can be reached to 806.60 and 876.60mg/g in a wide pH ranged from 3.0 to 11.0, respectively. And the adsorption equilibrium can be reached within 90min for TC and 50min for CTC. The magnetic porous adsorbent had good reusability, which can still attain a high adsorption capacity of 759.82 and 842.99mg/g for TC and CTC after five consecutive adsorption cycles, respectively. Therefore, the as-prepared CTS-g-AMPS magnetic adsorbent is potential to be used for adsorption removal of antibiotics from water., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Guided by a "chemistry first" approach using molecular networking, eight new bright-blue colored natural compounds, namely dactylocyanines A-H (3-10), were isolated from the Polynesian marine sponge Dactylospongia metachromia. Starting from ilimaquinone (1), an hemisynthetic phishing probe (2) was prepared for annotating and matching structurally related natural substances in D. metachromia crude extract network. This strategy allowed characterizing for the first time in Nature the blue zwitterionic quinonoid chromophore. The solvatochromic properties of the latter are reported., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The widespread use of antibiotics and heavy metals in livestock farms results in large residues of antibiotics and heavy metals in the livestock manure. Composting technology can biodegrade residual antibiotics and solidify heavy metals. A pilot composting reactor was used to analyze the characteristics of chlortetracycline (CTC) removal at different antibiotic concentrations[0 mg·kg -1 (CK), 10 mg·kg -1 (T1), and 50 mg·kg -1 (T2)]. Moreover, the morphological changes in heavy metals during the composting process were analyzed. After composting, no chlortetracycline was detected in the CK group and the antibiotics degradation rates of T1 and T2 groups reached 96.31% and 97.32%, respectively. The chlortetracycline degradation fits the pseudo-first-order kinetics model. Heavy metals can be solidified during the composting; thus, the bioavailable state of Cu and Zn (exchangeable state, reducible state) changed into the oxidation state and residues with apparent passivation formed. The correlation analysis showed that the removal of CTC showed strong positive correlations with the biological available Cu and Zn.

Residual emerging contaminants in wastewater sludge remain an obstacle for its wide and safe applications such as landfilling and bio-fertilizer. In this study, the feasibility of individual ultrasonication (UlS) and Fenton oxidation (FO) and combined, Ferro-sonication processes (FO) on the degradation of chlortetracycline (CTC) in wastewater sludge was investigated. UlS parameters such as amplitude and sonication time were optimized by response surface methodology (RSM) for further optimization of FS process. Generation of highly reactive hydroxyl radicals in FO and FS processes were compared to evaluate the degradation efficiency of CTC. Increasing in the ratio of hydrogen peroxide and iron concentration showed increased CTC degradation in FO process; whereas in FS, an increase in iron concentration did not show any significant effect (p>0.05) on CTC degradation in sludge. The estimated iron concentration in sludge (115mg/kg) was enough to degrade CTC without the addition of external iron. The only adjustment of sludge pH to 3 was enough to generate in-situ hydroxyl radicals by utilizing iron which is already present in the sludge. This observation was further supported by hydroxyl radical estimation with adjustment of water pH to 3 and with and without the addition of iron. The optimum operating UlS conditions were found to be 60% amplitude for 106min by using RSM. Compared to standalone UlS and FO at 1:1 ratio, FS showed 15% and 8% increased CTC degradation respectively. In addition, UlS of sludge increased estrogenic activity 1.5 times higher compared to FO. FS treated samples did not show any estrogenic activity., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In the last years, increasing attention has been paid on the presence of antibiotics in aqueous environments due to their ecological damage and potential adverse effects on organisms. Membrane biofilm reactors (MBfR) have been gained a significant popularity as an advanced wastewater treatment technology in removing of organic micro-pollutants. In this study, the performance of H 2 -MBfR for simultaneous removal of nitrate and chlortetracycline, formation of transformation products and community analysis of the biofilm grown on the gas permeable hollow fiber membranes was evaluated by considering effect of the hydraulic retention time, surface loadings of target pollutants and H 2 pressure. The results showed that the simultaneous chlortetracycline (96%) and nitrate removal (99%) took placed successfully under the conditions of 5h HRT and 2psi H 2 pressure. It has been determined that the main elimination process was biodegradation and Betaproteobacteria species was responsible for chlortetracycline degradation., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A highly effective analytical method for multi-residue determination of antibiotics in aquifer sediments was first established in this study. Microwave-assisted solvent extraction (MASE) and solid-phase extraction were used for sample pre-concentration and purification, ultra-high performance liquid chromatography coupled to hybrid quadrupole-high resolution Orbitrap mass spectrometry (UHPLC-Q-Orbitrap) was applied for detection. For high resolution mass spectrometry (HRMS), the target compounds were tentatively identified by retention time and accurate mass which was measured with precursor ions in Target-SIM scan, and then confirmed by the monitoring of daughter ion fragments which were generated in dd-MS(2) scan. The results provided good mass accuracy with mass deviations below 2ppm (except norfloxacin with -2.3ppm) for quantitative analysis of the compounds by HRMS. Reasonable recoveries of all analytes were obtained more than 60% (except doxytetracycline) in fortification samples at concentrations higher than 10μgkg(-1). Relative standard deviations of repeatability and inter-day precision were below 21% and 11%. Limits of detection (LOD) ranged from 0.1 to 3.8μgkg(-1), whereas limits of quantification (LOQ) were established between 0.3-9.0μgkg(-1). The method was applied to analyze real aquifer sediment samples in different aquifer depth of 4.0, 7.5, 13.0 and 18.0m. Chlorotetracycline and ofloxacin were observed at relative high concentrations of 53 and 19μgkg(-1) respectively in 18.0m deepness. The exposure to low doses of these compounds in subsurface environment increases concerns on long-term ecological security of underground system., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Antibiotics such as sulfonamides and tetracyclines are frequently used in veterinary medicine. Due to incomplete absorption in the animal gut and/or unmetabolized excretion, the substances can enter the environment by using manure as soil fertilizer. The anaerobic fermentation process of biogas plants is discussed as potential sink for antibiotic compounds. However, negative impacts of antibiotics on the fermentation process are suspected. The elimination of sulfadiazine, sulfamethazine, tetracycline and chlortetracycline in semi-continuous lab-scale fermenters was investigated. Both biogas production and methane yield were not negatively affected by concentrations up to 38 mg per kg for sulfonamides and 7 mg per kg for tetracyclines. All substances were partly eliminated with elimination rates between 14% and 89%. Both matrix and structure of the target molecule influenced the elimination rate. Chlortetracycline was mainly transformed into iso-chlortetracycline. In all other cases, the elimination pathways remained undiscovered; however, sorption processes seem to have a negligible impact., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The lack of accurate process models and reliable online sensors for substrate measurements poses significant challenges for controlling substrate feeding accurately, automatically and optimally in fed-batch fermentation industries. It is still a common practice to regulate the feeding rate based upon manual operations. To address this issue, a hybrid intelligent control method is proposed to enable automatic substrate feeding. The resulting control system consists of three modules: a presetting module for providing initial set-points; a predictive module for estimating substrate concentration online based on a new time interval-varying soft sensing algorithm; and a feedback compensator using expert rules. The effectiveness of the proposed approach is demonstrated through its successful applications to the industrial fed-batch chlortetracycline fermentation process., (Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.)

Tetracyclines (TCs), including tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC), are amongst the most common antibiotics used in animal husbandry. Residual amounts of these antibiotics in the environment are a concern because they contribute to selection of resistant bacteria. In this study, we investigated the biodegradation of three TCs in swine wastewater. In batch experiments, OTC and CTC were completely degraded at d 18 and 20, respectively, but TC was remained at 7.1% after 20 d incubation. The degradation rates of TCs in the wastewater were in the order of OTC > CTC > TC. Degradation of the TCs was enhanced by the addition of enzyme extract from spent mushroom compost (SMC) of Pleurotus eryngii. The degradation rates were higher with the addition of extract-containing microcapsules than suspended enzyme extract in swine wastewater. In the bioreactor experiment, the addition of extract-containing microcapsules enhanced the removal rates of the three TCs, and adding TCs twice maintained enzyme activity in the swine wastewater. Of the microorganism strains isolated from the wastewater samples, strain HL2 (identified as Xanthobacter flavus) showed the best degrading ability.

Zeolite imidazolate framework-8 (ZIF-8) was used as the novel sorbent for on-line solid-phase extraction coupled with high-performance liquid chromatography (HPLC) for the determination of oxytetracycline (OTC), tetracycline (TC) and chlorotetracycline (CTC) in water and milk samples. 390mg of ZIF-8 was packed into a stainless steel column (3cm long×4.6mm i.d.) which was mounted on the HPLC injector valve to replace the sample loop. On-line solid-phase extraction of OTC, TC and CTC was achieved by loading sample solution at a flow rate of 3.0mLmin(-1) for 10min with the aid of a flow-injection system. The extracted analytes were subsequently eluted into a C18 analytical column (25cm long×4.6mm i.d.) for HPLC separation under isocratic condition with a mobile phase (10% MeOH-20% ACN-70% 0.02molL(-1) oxalic acid solution) at a flow rate of 1.0mLmin(-1). Under optimized conditions, the developed method gave the enhancement factors of 35-61, the linearity range of 5-1000μgL(-1), the detection limits of 1.5-8.0μgL(-1), quantification limits of 5.0-26.7μgL(-1), uncertainties of 0.9-1.1μgL(-1), and the sample throughput of 4 samples h(-1). The recoveries of OTC, TC and CTC at 50μgL(-1) in water and milk samples ranged from 70.3% to 107.4%., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A very accommodating host: Three tetracycline biosynthetic pathways were overexpressed and manipulated in the heterologous host Streptomyces lividans K4-114. Through the inactivation of various genes and characterization of the resulting biosynthetic intermediates, new tetracycline-modifying enzymes were identified (see scheme)., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Magnetic carbon nanoparticles with core/shell structure (Fe3C/Fe@C) and large surface areas were synthesized via hydrothermal method followed with heat treatment under N2 atmosphere. The adsorbent has strongly magnetic cores and graphitized carbon shell. The removal efficiency of chlortetracycline (CTC) from aquatic environment by Fe3C/Fe@C was investigated. The results showed that Fe3C/Fe@C exhibited ultrahigh adsorption ability to CTC. The adsorption behavior of CTC on FeC/Fe@C fitted the pseudo-second-order kinetic model, and the adsorption equilibrium was achieved within 24 h. The adsorption ability of CTC increased with solution pH at pH 3.5-7.5, but decreased with further increase of pH (pH 7.5-8.5). CTC adsorption decreased with solution temperature and increased with ionic strength. As the concentration of coexisting humic acid in solution ranged in 10-50 mg x L(-1), the adsorption ability of CTC on Fe3C/Fe@C was only decreased by 10%-20%. Under the optimal conditions (pH = 7.5, T = 293 K), the maximum adsorption capacity of CTC on Fe3C/Fe@C calculated by Langmuir was 909 mg x g(-1), which was significantly higher than those obtained on sediment or minerals. More importantly, Fe3C/Fe@C adsorbed with CTC can be collected from water sample under a magnetic field rapidly for special disposal, which avoids secondary pollution of water. These results indicate that Fe3C/Fe@C is a potentially efficient, green adsorbent for removal of tetracycline antibiotics from aquatic environment.

The history of the tetracyclines involves the collective contributions of thousands of dedicated researchers, scientists, clinicians, and business executives over the course of more than 60 years. Discovered as natural products from actinomycetes soil bacteria, the tetracyclines were first reported in the scientific literature in 1948. They were noted for their broad spectrum antibacterial activity and were commercialized with clinical success beginning in the late 1940s to the early 1950s. The second-generation semisynthetic analogs and more recent third-generation compounds show the continued evolution of the tetracycline scaffold toward derivatives with increased potency as well as efficacy against tetracycline-resistant bacteria, with improved pharmacokinetic and chemical properties. Their biologic activity against a wide spectrum of microbial pathogens and their uses in mammalian models of inflammation, neurodegeneration, and other biological systems indicate that the tetracyclines will continue to be successful therapeutics in infectious diseases and as potential therapeutics against inflammation-based mammalian cell diseases., (© 2011 New York Academy of Sciences.)

Chlortetracycline (CTC) has been widely used in veterinary medicines and disease treatment. Heavy metals and antibiotics often coexist in soil due to land application of animal wastes and other sources of inputs. On the basis of the OECD Guideline 106, the batch equilibrium experimental method was employed to investigate sorption and desorption processes of CTC in cinnamon soil with and without soil organic matter (SOM) and examine the effect of Cd2+ on these processes. Results showed that the Freundlich model was the best isotherm to describe the experimental data for adsorption and desorption of CTC in soil on single and combined pollution conditions. In these a single chlortetracycline pollution and chlortetracycline-Cd combined pollution conditions, removal of SOM could increase the CTC adsorption capacity (K(f)) and adsorption intensity (1/n). The apparent adsorption-desorption hysteresis was found in cinnamon soil with and without SOM. In single pollution condition, the removal of SOM could significantly increase HI in cinnamon soil from 0.81 to 1.06. In all cases of CTC combined with Cd desorption studies, it had been known that HI of CTC in soils with SOM (1.11) were higher than those without SOM (0.84). This study was provided available data and parameters to set a more complete model to predict environmental concentration of CTC and evaluation their environmental risk.

A specific, sensitive and robust liquid chromatography tandem mass spectrometry method for determining oxytetracycline, tetracycline, chlortetracycline and doxycycline in royal jelly and honey samples is presented. Extraction of drug residues was performed by ammonium acetate buffer as extractant followed by a clean-up with metal chelate affinity chromatography and solid-phase extraction. Tetracycline analysis was performed using liquid chromatography-electrospray ionisation-tandem mass spectrometry. The presented method is the first validated for royal jelly and in accordance with the requirements set by Commission Decision 2002/657/EC. Recoveries of the methods, calculated spiking the samples at 5.0, 10.0, 20.0 and 30.0 μg kg(-1), were 79% to 90% for honey and 77% to 90% for royal jelly. The intra-day precision (RSD) ranged between 8.1% and 15.0% for honey and from 9.1% to 16.3% for royal jelly, while inter-day precision values were from 10.2% to 17.6% and from 10.6% to 18.4% respectively for honey and royal jelly. Linearity for the four analytes was calculated from 5.0 to 50.0 μg kg(-1). The decision limits (CCα) ranged from 6.2 to 6.4 μg kg(-1) and from 6.1 to 6.5 μg kg(-1) for honey and royal jelly, respectively. Detection capabilities values (CCβ) ranged between 7.2 and 7.7 μg kg(-1) and from 7.3 to 7.9 μg kg(-1) respectively for honey and royal jelly. The developed method is currently in use for confirmation of the official control analysis of honey and royal jelly samples.

Oxytetracycline (OTC) and chlortetracycline (CTC) are broad-spectrum antibiotics used in livestock production. Although laboratory-scale studies have shown that extractable concentrations of these compounds decrease over time within treated and untreated manures and soils, there is relatively little information from farm-scale experiments. The objective of this study was to determine the effect of different levels of management on manure pile temperature profiles and on the fate of OTC and CTC in manure from therapeutically treated calves. Four treatments were designed to span a range of management options - from simply piling up the manure to amending it with straw to increase aeration and adding insulating layers of straw. Replicate samples of antibiotic-containing calf manure were held at ambient temperature or placed in three locations within replicate 3m(3) piles of beef manure. During the 28-day incubation period, concentrations of buffer-extractable OTC and CTC/ECTC (the summed concentrations of CTC and its epimer 4-epi-chlortetracycline (ECTC)) in manure samples incubated at ambient temperature (11-24 degrees C) decreased 75% (from 18 to 4.6 mg kg(-1) dry weight (DW)) and 90% (from 192 to 16 mg kg(-1) DW), respectively. Concentrations of the CTC metabolite iso-chlortetracycline (ICTC) decreased 90% (from 37 to 3 mg kg(-1) DW). OTC and CTC/ECTC concentrations in samples incubated for 28 days within a non-amended manure pile decreased 91% and >99%, respectively. During that period, the manure pile temperature ranged from 36 degrees C to 45 degrees C. Manure piles insulated with a blanket of straw and/or amended with straw (3:1, v/v) attained temperatures up to 70 degrees C and contained very low levels of OTC, CTC/ECTC, and ICTC (ranging from <0.1 to 0.4 mg kg(-1) DW) after 28 days.

To better understand the transformation of chlortetracycline (CTC) under the oxidation of manganese dioxide (MnO2), kinetics of CTC reaction with MnO2 were investigated and the effects of MnO2 initial concentration, pH, and temperature on kinetics were also discussed. Results showed that loss of CTC was not detected in the absence of MnO2. But CTC was rapidly degraded along with the generation of Mn2+ in the presence of MnO2, which indicated that this process was an oxidation-reduction reaction. In order to explain the adsorption of CTC on MnO2 surface, two different approaches (filtration and oxalic acid addition) were used to quench the reactions. Oxidation was observed dominantly in the initial stage compared with adsorption, and adsorption become noticeable after the reaction reached an equilibrium level. The reaction rate of CTC increased with the increase of MnO2 initial concentration and temperature of the reaction system. In addition, the reaction rate of CTC also decreased significantly as the pH of reaction mixture increased from 3.77 to 7.41, which was caused by the decreased adsorption of CTC on MnO2 with the increase of pH. Over the entire pH range (3.77-7.41), the speciation of CTC transited from cation and then zwitterion to anion, however, the MnO2 surface exhibited all with negative charges because its zeta-potential (pH point of zero charge) was 2.25. Thus, pH increase would result in the decline of the adsorption force between CTC speciation and the MnO2 surface.

Chlortetracycline (CTC) is one of only ten antibiotics licensed in the U.S.A. for use as growth promoters for livestock. The widespread use and persistence of CTC may contribute in development of antibiotic-resistant bacteria. The objective of this study was to determine the effect of composting on the fate of CTC residues found in manure from medicated animals. The effect of CTC residues on composting was also investigated. Five beef calves were medicated for 5 days with 22 mg/kg/day of CTC. Manure samples collected from calves prior to and after medication were mixed with straw and woodchips, and aliquots of the subsequent mixtures were treated in laboratory composters for 30 days. In addition, aliquots of the CTC-containing mixture were incubated at 25 degrees C or sterilized followed by incubation at 25 degrees C and 55 degrees C (composting temperature). The presence of CTC did not appear to affect the composting process. Concentrations of CTC/ECTC (the summed concentrations of CTC and its epimer ECTC) in the composted mixture (CM) and sterilized mixture incubated at 55 degrees C (SM55) decreased 99% and 98% (from 113 microg/g dry weight (DW) to 0.7 microg/g DW and 2.0 microg/g DW), respectively, in 30 days. In contrast, levels of CTC/ECTC in room temperature incubated (RTIM) and sterilized mixture incubated at 25 degrees C (SM25) decreased 49% and 40% (to 58 microg/g DW and 68 microg/g DW), respectively, after 30 days. Concentrations of the CTC metabolite, iso-chlortetracycline (ICTC), in CM and SM55 decreased more than 99% (from 12 microg/g DW to below quantitation limit of 0.3 microg/g DW) in 30 days. ICTC levels in RTIM and SM25 decreased 80% (to 4 microg/g DW) in 30 days. These results confirm and extend those from previous studies that show the increased loss of extractable CTC residues with increased time and incubation temperature. In addition, our results using sterile and non-sterile samples suggest that the decrease in concentrations of extractable CTC/ECTC at 25 degrees C and 55 degrees C (composting temperature) is due to abiotic processes.

Eight antibiotics, chlortetracycline, demeclocycline, doxycycline, methacycline, minocycline, oxytetracycline, tetracycline and rolitetracycline, were separated and quantified in Spanish honey extracts of different floral origin using a commercial RP-C18 HPLC column and two different on-line detectors (diode array and electrospray time-of-flight mass spectrometry (ESI-TOF-MS) systems). Operating a linear gradient at a flow of 2 ml min(-1) the HPLC separation of the eight antibiotics was obtained within 10 min with good peak symmetry and an acceptable resolution (2.1) for the critical band pair rolitetracycline and oxytetracycline. Values of the numbers of theoretical plates (N) were comprised between 2328 and 19448 while the limits of detection in honey were within 0.02-1.03 microg kg(-1) in the case of UV detection and 0.05-0.76 microg kg(-1) for ESI-TOF-MS detection (operating in negative mode). A recovery study was carried out by preparing some quality control samples at four levels of concentration (10, 25, 50 and 100 microg kg(-1)) and percentages between 72% and 98% were attained.

Four different techniques for the extraction of veterinary drugs were compared. The use of a high speed mixer/emulsifier, an ultrasonic bath, a Stomacher and an end-over-end mixer were used to extract both incurred and fortified residues of chlortetracycline, sulphadiazine and flumequine from chicken muscle. For each drug, similar analytical recoveries from fortified muscle samples were obtained using each of the extraction techniques. However, for each analyte the highest drug concentration detected in incurred samples was obtained following preparation using a mixer/emulsifier extraction. Residue concentrations obtained using sonication, Stomacher or end-over-end mixer procedures were as low as 20% of those obtained using the mixer/emulsifier. This highlights the need to measure both incurred and spiked samples during method validation. A survey of published methods indicated that 75% of laboratories use some form of high-speed homogenization for the extraction of drug residues from tissue. However only 52% reported detection of incurred residues. More than two-thirds of methods that used other forms of extraction did not measure incurred residues. The use of such methods has implications for the statutory detection of veterinary drug residues.

The separation and quantitative performance parameters for tetracycline, chlortetracycline and oxytetracycline antibiotics were investigated by capillary zone electrophoresis coupled with fast cyclic voltammetric detection. Optimization of pH and complexation with a boric acid-sodium tetraborate buffer provided good resolution of all compounds. Detection by electrochemical reduction using fast on-line cyclic voltammetric detection with a Hg-film-microm electrode gave detection limits (2 x peak-to-peak baseline noise) of 7 x 10(-7) mol/l for tetracycline and chlortetracycline, and 1.5 x 10(-6) mol/l for oxytetracycline. The influence of electrode material, potential range and scan rate was examined and discussed. Optimal electrochemical detection was obtained at a Hg-film electrode with a waveform that consisted of an initial constant potential of -0.6 V for 200 ms followed by a cyclic voltammetry (CV) scan at 300 V/s from - 0.6 V to a vertex potential of 1.7 V. The analytical signal was obtained by plotting the integrated values of the CV current from each applied waveform as a function of time. The calibration plot (peak areas) for each separated peak was found to be linear over three-orders of magnitude.

A sensitive high-performance liquid chromatographic technique with amperometric detection has been developed for the determination of seven commercially used tetracyclines in bulk powders and pharmaceutical preparations. The technique is based on the oxidation of these compounds and their contaminants at the glassy carbon electrode. The extraction procedures are simple and the HPLC conditions separate the tetracyclines from their major degradation products. The chromatography was performed using a commercially available octadecylsilane column, with a mobile phase: KH2 PO4 (pH = 2.5; 0.05 M) - acetonitrile (84:16, v/v) and detection at 1.2 V. The technique permits the simultaneous determination of trace amounts of chlortetracycline, demeclocycline, doxycycline, methacycline, minocycline, oxytetracycline and tetracycline as well as the separation of their common impurities (epi, anhydro and epianhydro contaminants) with detection limits of 0.1-1.0 ng microl(-1) and recoveries of 99.1-100.4%. No interference was observed from the commonly present excipients in pharmaceutical formulations.

This method was developed to separate, detect, and quantitate oxytetracycline (OTC) or chlortetracycline hydrochloride (CTC.HCl) in animal feeds in the presence of 11 other drugs: 3 nitrofurans, 2 macrolide antibiotics, 3 sulfonamides, 2 coccidiostatics, and 1 antibacterial growth promoter. OTC or CTC.HCl was separated from coexisting drugs and detected by thin-layer chromatography, then quantitated microbiologically by the agar diffusion method. Analysis of 125 experimental animal feed samples fortified at 5 levels (7.5-400 ppm) with OTC or CTC.HCl and at 1 level (50 ppm) with the rest of the drugs, respectively, gave a limit of quantitation of 1.25 or 0.625 ppm, a recovery of 90.6 or 92.9%, and a coefficient of variation of 2.9-6.1 or 2.3-4.4%.

A screen for antibiotics with activity against tetracycline-resistant microorganisms has led to the isolation of Dactylosporangium sp. (ATCC 53693), a producer of several novel tetracycline derivatives. The major fermentation products, dactylocyclines A and B, were purified and MIC values determined against tetracycline-resistant and tetracycline-sensitive Gram-positive bacteria. The dactylocyclines represent the first naturally occurring tetracycline C2 amides which lack cross resistance with tetracycline.

Keto and enol tautomers of chlortetracycline and 4-epichlortetracycline were successfully separated by low temperature high-performance liquid chromatography on poly(styrene-divinylbenzene)copolymer. The keto-enol tautomerism occurs between C-11a and C-12. The elucidation of the chemical structure of the tautomers was realized with the help of on-line and off-line UV-spectrophotometry and of 13C and 1H NMR spectrometry. The kinetics of the equilibrium reaction were investigated.

A novel tetracycline antibiotic, Sch 33256, was isolated from a culture broth of a new species of Actinomadura. The antibiotic was isolated by solvent extraction, Sephadex G-25 column chromatography and crystallization. The structure was determined by comparison of the spectra with that of chlortetracycline. Spectroscopic analysis of the compound yielded 2'-N-methyl-8-methoxychlortetracycline as the proposed structure.

An actinomycete identified as a Dactylosporangium sp. produces a new tetracycline, 4a-hydroxy-8-methoxychlortetracycline (Sch 34164). The addition of magnesium ions to complex fermentation media increased the antibiotic titers. Sch 34164 was isolated by solvent extraction and Sephadex G-25 column chromatography. The novel structure was proposed based on spectroscopic analysis. The shift of C-4a (35 to 77 ppm) and C-8 (140 to 163 ppm) in the 13C NMR as compared to chlortetracycline was indicative of the novel hydroxyl and methoxy substituents, respectively.

Actinomadura brunnea produces 2'-N-methyl-8-methoxychlortetracycline. A derivative of this strain has been isolated that is specifically blocked in methylation of the 2'-amino position. This isolate was detected by screening approximately 30,000 colonies of a mutagenized population of Actinomadura brunnea using a direct soft agar overlay with an Escherichia coli indicator. The antibiotic produced by the blocked mutant has been identified as 8-methoxychlortetracycline (Sch 36969) based upon its biological activity, relative mobility on TLC and HPLC, and spectroscopic data.