Analysis of oxytetracycline, tetracycline, and chlortetracycline in water using solid-phase extraction and liquid chromatography-tandem mass spectrometry

The behavior of pharmaceutically active compounds and contrast agents during wastewater treatment - Combining sampling strategies and analytical techniques: A critical review

Increasing consumption of pharmaceuticals and the respective consequences for the aquatic environment have been the focus of many studies over the last thirty years. Various aspects in this field were investigated, considering diverse pharmaceutical groups and employing a wide range of research methodologies. Various questions from the perspectives of different research areas were devised and answered, resulting in a large mix of individual findings and conclusions. Collectively, the results of the studies offer a comprehensive overview. The large variety of methods and strategies, however, demands close attention when comparing and combining information from heterogeneous projects. This review critically examines the application of diverse sampling techniques as well as analytical methods in investigations concerning the behavior of pharmaceutically active compounds (PhACs) and contrast agents (CAs) in wastewater treatment plants (WWTPs). The combination of sampling and analysis is discussed with regard to its suitability for specific scientific problems. Different research focuses need different methods and answer different questions. An overview of studies dealing with the fate and degradation of PhACs and CAs in WWTPs is presented, discussing their strategic approaches and findings. This review includes surveys of anticancer drugs, antibiotics, analgesics and anti-inflammatory drugs, antidiabetics, beta blockers, hormonal contraceptives, lipid lowering agents, antidepressants as well as contrast agents for X-ray and magnetic resonance imaging.

Analytical methods for determining environmental contaminants of concern in water and wastewater

Control and prevention of environmental pollution have emerged as paramount global concerns. Anthropogenic activities, such as industrial discharges, agricultural runoff, and improper waste disposal, introduce a wide range of contaminants into various ecosystems. These pollutants encompass organic and inorganic compounds, particulates, microorganisms, and disinfection by-products, posing severe threats to human health, ecosystems, and the environment. Effective monitoring methods are indispensable for assessing environmental quality, identifying pollution sources, and implementing remedial measures. This paper suggests that the development and utilization of highly advanced analytical tools are both essential for the analysis of contaminants in water samples, presenting a foundational hypothesis for the review. This paper comprehensively reviews the development and utilization of highly advanced analytical tools which is mandatory for the analysis of contaminants in water samples. Depending on the specific pollutants being studied, the choice of analytical methods widely varies. It also reveals insights into the diverse applications and effectiveness of these methods in assessing water quality and contaminant levels. By emphasizing the critical role of the reviewed monitoring methods, this review seeks to deepen the understanding of pollution challenges and inspire innovative monitoring solutions that contribute to a cleaner and more sustainable global environment.•Urgent global concerns: control and prevention of pollution from diverse sources.•Varied contaminants, diverse methods: comprehensive review of analytical tools.•Inspiring a sustainable future: innovative monitoring for a cleaner environment.

Influence of Four Veterinary Antibiotics on Constructed Treatment Wetland Nitrogen Transformation

The use of wetlands as a treatment approach for nitrogen in runoff is a common practice in agroecosystems. However, nitrate is not the sole constituent present in agricultural runoff and other biologically active contaminants have the potential to affect nitrate removal efficiency. In this study, the impacts of the combined effects of four common veterinary antibiotics (chlortetracycline, sulfamethazine, lincomycin, monensin) on nitrate-N treatment efficiency in saturated sediments and wetlands were evaluated in a coupled microcosm/mesocosm scale experiment. Veterinary antibiotics were hypothesized to significantly impact nitrogen speciation (e.g., nitrate and ammonium) and nitrogen uptake and transformation processes (e.g., plant uptake and denitrification) within the wetland ecosystems. To test this hypothesis, the coupled study had three objectives: 1. assess veterinary antibiotic impact on nitrogen cycle processes in wetland sediments using microcosm incubations, 2. measure nitrate-N reduction in water of floating treatment wetland systems over time following the introduction of veterinary antibiotic residues, and 3. identify the fate of veterinary antibiotics in floating treatment wetlands using mesocosms. Microcosms containing added mixtures of the veterinary antibiotics had little to no effect at lower concentrations but stimulated denitrification potential rates at higher concentrations. Based on observed changes in the nitrogen loss in the microcosm experiments, floating treatment wetland mesocosms were enriched with 1000 μg L-1 of the antibiotic mixture. Rates of nitrate-N loss observed in mesocosms with the veterinary antibiotic enrichment were consistent with the microcosm experiments in that denitrification was not inhibited, even at the high dosage. In the mesocosm experiments, average nitrate-N removal rates were not found to be impacted by the veterinary antibiotics. Further, veterinary antibiotics were primarily found in the roots of the floating treatment wetland biomass, accumulating approximately 190 mg m-2 of the antibiotic mixture. These findings provide new insight into the impact that veterinary antibiotic mixtures may have on nutrient management strategies for large-scale agricultural operations and the potential for veterinary antibiotic removal in these wetlands.

Liquid Chromatography-Tandem Mass Spectrometry Detection of Human and Veterinary Drugs and Pesticides in Surface Water

Antibiotics and pesticides are widespread in most rivers and lakes due to the overuse of antibiotics and pesticides, but there are few methods for simultaneous analysis of antibiotics and pesticides in aquatic environments. To address this knowledge gap, a concise and sensitive analytical method is proposed in which three classes of human and veterinary drugs (sulfonamides, macrolides, and hormones) and two classes of pesticides (organophosphorus and neonicotinoids) are simultaneously extracted and determined in surface water. The solid-phase extraction column with Cleanert PEP-2 was preconditioned sequentially with 6 mL of methanol, ultrapure water, and citric acid buffer (pH 3.0) each for simultaneous extraction and further purification. The forty-seven target analytes were analysed by LC-MS/MS in positive and negative ion modes. The LC separation was performed using a Sigma-Aldrich C18 column with 0.1% formic acid in water and acetonitrile as a gradient eluting mobile phase in positive ion mode. The internal standard method was used to overcome the inevitable matrix effects in LC-MS/MS analysis. The matrix effects of most target analytes were in the range of 27-151%. The recoveries of forty analytes in the three concentrations (10, 50, and 100 ng L-1) of surface water spiked samples ranged from 41 to 127%. The method quantitative limits of the analytes were in the range of 0.40-5.49 ng L-1. Application of the method to analyze samples in the eight runoff outlets of the Pearl River Delta showed that some antibiotics and pesticides were detected, and the concentration of parathion was as high as 154 ng L-1. A powerful tool for quickly and efficiently screening for contaminants in surface water has been presented.

Slower antibiotics degradation and higher resistance genes enrichment in plastisphere

Microplastics (MPs) are increasingly entering the urban aquatic ecosystems, and the environmental significance and health risks of plastisphere, a special biofilm on MPs, have received widespread attention. In this study, MPs of polylactic acid (PLA) and polyvinyl chloride (PVC) and quartzite were incubated in an urban water environment, and the tetracycline (TC) degradation ability was compared. Approximatedly 24% of TC biodegraded in 28 d in the water-quartzite system, which is significantly higher than that in the water-PLA (17.3%) and water-PVC systems (16.7%). Re-incubation of microorganisms in biofilms affirmed that quartzite biofilm has a higher TC degradation capacity than the plastisphere. According to high-throughput sequencing of 16S rRNA and metagenomic analysis, quartzite biofilm contained more abundant potential TC degrading bacteria, genes related to TC degradation (eutG, aceE, and DLAT), and metabolic pathways related to TC degradation. An oligotrophic environment on the quartzite surface might lead to the higher metabolic capacity of quartzite biofilm for unconventional carbons, e.g., TC. It is also found that, compared with quartzite biofilm, the distinct microbes in the plastisphere carried more antibiotic resistance genes (ARGs). Higher affinity of MPs surface to antibiotics may lead to higher antibiotics stress on the plastisphere, which further amplify the carrying capacity for ARGs of microorganisms in the plastisphere. Compared to the nondegradable PVC MPs, surface of the biodegradable PLA plastics harbored significantly higher amounts of biomass and ARGs. Compared to the mineral particles, the capability of plastisphere has lower ability to degrade unconventional carbon sources such as the refractory organic pollutants, due to the abundance of carbon sources (adsorbed organic carbon and endogenous organic carbon) on the MPs surface. Meanwhile, the stronger adsorption capacity for pollutants also leads to higher pollutant stress (such as antibiotic stress) in plastisphere, which in turn affects the microbiological characteristics of the plastisphere itself, such as carrying more ARGs.

Online prediction of total sugar content and optimal control of glucose feed rate during chlortetracycline fermentation based on soft sensor modeling

In the process of chlortetracycline (CTC) fermentation, no instrument can be used to measure the total sugar content of the fermentation broth online due to its high viscosity and large amount of impurities, so it is difficult to realize the optimal control of glucose feed rate in the fermentation process. In order to solve this intractable problem, the relationship between on-line measurable parameters and total sugar content (One of the parameters that are difficult to measure online) in fermentation tank is deeply analyzed, and a new soft sensor model of total sugar content in fermentation tank and a new optimal control method of glucose feed rate are proposed in this paper. By selecting measurable variables of fermentation tank, determining different fermentation stages, constructing recursive fuzzy neural network (RFNN) and applying network rolling training method, an online soft sensor model of total sugar content is established. Based on the field multi-batch data, the change trend of the amount of glucose feed required at each fermentation stage is divided, and the online prediction of total sugar content and the optimal control strategy of glucose feed rate are realized by using the inference algorithm of expert experience regulation rules and soft sensor model of total sugar content. The experiment results in the real field demonstrate that the proposed scheme can effectively predict the total sugar content of fermentation broth online, optimize the control of glucose feed rate during fermentation process, reduce production cost and meet the requirements of production technology.

Determination of Tetracycline Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplet Followed by HPLC-UV System

BACKGROUND

Tetracyclines (TCs) are a group of broad-spectrum antibiotics that may be used to control bacterial diseases in humans or are applied as feed additives to enhance growth in farm animals. TCs are released into the aquatic environment via different pathways. Many analytical methods combined with a preconcentration step have been introduced for the determination of TC in various environmental samples.

OBJECTIVE

The objective this paper is developing reliable analytical methods for determination of TC trace in various environmental samples.

METHOD

In the present work, combined ultrasound-assisted and dispersive liquid-liquid microextraction according to the solidification of floating organic drop as a sample preconcentration procedure for determining TC hydrochloride HPLC in water and serum samples was used.

RESULTS

A series of parameters, including the type and volume of disperser and extraction solvents, salt effect, extraction time, and pH of solution influencing the extraction efficiency of UA-DLLME-SFO was examined. Enrichment factors were in the range of 125-137 for TC hydrochloride under optimum conditions. The linear range was calculated from 0.005 to 3 mg/L and LOD at 0.002 mg/L. RSDs were in the range of 2.7 to 3.2 (n = 5). The UA-DLLME-SFO method used in water and serum samples revealed good extraction recoveries with RSD of 2.7-4.3%.

CONCLUSIONS

This method significantly decreased the organic solvent volume from 3 mL to 90 µL, also LOD and linear ranges were lower than or almost close to levels obtained in other research studies. In this procedure, an ultrasound bath enhanced the mixing and contact between the sample solution and the extraction solvent.

Tetracycline Antibiotics: Elucidating the Electrochemical Fingerprint and Oxidation Pathway

Herein, a complete study of the electrochemical behavior of the most commonly used tetracycline antibiotics (TCs) on unmodified carbon screen-printed electrodes (SPEs) is presented. In addition, the oxidation pathway of TCs on SPE is elucidated, for the first time, with liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Square wave voltammetry (SWV) was used to study the electrochemical fingerprint (EF) of the antibiotics shaping the different oxidation processes of the TCs in a pH range from 2 to 12. Their characteristic structure and subsequent EF offer the possibility of distinguishing this class of antibiotics from other types. Under the optimized parameters, calibration curves of tetracycline (TET), doxycycline (DOXY), oxytetracycline (OXY), and chlortetracycline (CHL) in a Britton Robinson buffer solution (pH 9) exhibited a linear range between 5 and 100 µM with excellent reproducibilities (RSDTET = 3.01%, RSDDOXY = 3.29%, RSDOXY = 9.78% and RSDCHL = 6.88% at 10 µM, N = 3) and limits of detection (LOD) of LODTET = 4.15 µM, LODDOXY = 2.14 µM, LODOXY = 3.07 µM and LODCHL = 4.15 µM. Furthermore, binary, tertiary, and complex mixtures of all TCs were analyzed with SWV to investigate the corresponding EF. A dual pH screening (pH 4 and pH 9), together with the use of a custom-made Matlab script for data treatment, allowed for the successful confirmation of a single presence of TCs in the unknown samples. Overall, this work presents a straightforward study of the electrochemical behavior of TCs in SPE, allowing for the future on-site identification of residues of tetracycline antibiotics in real samples.

Tetracyclines in the environment: An overview on the occurrence, fate, toxicity, detection, removal methods, and sludge management

Tetracyclines (TCs) are a group of broad-spectrum antibiotics having vast human, veterinary, and aquaculture applications. The continuous release of TCs residues into the environment and the inadequate removal through the conventional treatment systems result in its prevalent occurrence in soil, surface water, groundwater, and even in drinking water. As aqueous TCs contamination is the tip of the iceberg, and TCs possess good sorption capacity towards soil, sediments, sludge, and manure, it is insufficient to rely on the sorptive removal in the conventional water treatment plants. The severity of the TCs contamination is evident from the emergence of TCs resistance in a wide variety of microorganisms. This paper reviews the recent research on the TCs occurrence in the environmental matrices, fate in natural systems, toxic effects, and the removal methods. The high performance liquid chromatography (HPLC) determination of TCs in environmental samples and the associated technology developments are analyzed. The benefits and limitations of biochemical and physicochemical removal processes are also discussed. This work draws attention to the inevitability of proper TC sludge management. This paper also gives insight into the limitations of TCs related research and the future scope of research in environmental contamination by TCs residues.

Antibiotic drugs alter zebrafish behavior

Antibiotics are widely used drugs in human and veterinary health as well as in the food industry. The majority of these compounds are, however, excreted unchanged and found as contaminants in water bodies. Although the toxicity of these drugs was previously studied in aquatic organisms, the behavioral effects of these pollutants have not been fully explored. Here we exposed adult zebrafish to environmentally relevant concentrations of different classes of antibiotics (Chlortetracycline, Ciprofloxacin, and Ceftazidime) and assessed zebrafish exploratory, cognitive, aggressive, and social behaviors. Ciprofloxacin, Chlortetracycline, and Ceftazidime exposure induced hyperlocomotion, which was characterized by an increase in the distance traveled in zebrafish. These antibiotics promoted cognitive decline and exacerbated aggressive behavior. In summary, this study shows that antibiotic contamination may impact zebrafish behavior in a short-time manner.

Effective removal of tetracycline from water by batch method using activated carbon, magnetic carbon nanocomposite, and membrane hybrid technology

In this study two adsorbents (activated carbon; AC and magnetic activated carbon; MCN) were prepared from Dalbergia sissoo sawdust and used as potential adsorbents for the removal of tetracycline (TC) from water. Both the adsorbents were characterized by instrumental techniques like energy dispersive x-ray (EDX), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), x-ray diffraction (XRD), surface area analyzer and thermal gravimetric/Differential thermal analysis (TG/DTA). The effect of antibiotic initial concentration, contact-time, pH, adsorbent-dose, and temperature were evaluated to determine optimum adsorption conditions. The optimum TC concentration for both AC and MCN was 120 mg/L while optimum time of saturation for both adsorbents was 120 min. The optimum pH determined was five while optimum adsorbent dose was 0.1 g. The adsorption isothermal data of both sets of experiments was best explained by Langmuir model. The kinetic data was well explained by pseudo-second order kinetics model. The ΔH° (enthalpy change) and ΔSo (entropy change) were; −14.989 and 25.174 kJ/mol for AC and −11.628 and 51.302 kJ/mol for MCN respectively. The values of Gibbs free energy (ΔG°) calculated for AC were 7.36, −7.99, −7.36, −7.61, and −8.12 kJ/mol while for MCN these were −15.02, −15.53, −16.05, −16.56, and −17.07 kJ/mol corresponding to temperatures; 298, 303, 313, 323, and 333 K. To control fouling in ultra-filtration, nano-filtration, and reverse osmosis membranes caused by TC, and both adsorbents, a continuous stirred reactor was connected in series with membrane pilot plant. The improvement brought about by both adsorbent in parameters like % retention and permeate flux was also evaluated. Comparatively, better improvement was brought about in % retention and permeates flux by MCN.

Synthesis and evaluation of bisulfate/mesylate-conjugated chlortetracycline with high solubility and bioavailability

The aim of this work is to improve the solubility and bioavailability of chlortetracycline and the function of the immune response. Chlortetracycline bisulfate and chlortetracycline mesylate were successfully synthesized and characterized with several techniques, including spectroscopy, chromatography and mass spectrometry, which demonstrated that the C4-dimethylamino group of chlortetracycline can accept a proton from sulfuric acid and methanesulfonic acid to form the corresponding salts. In addition, chlortetracycline bisulfate and chlortetracycline mesylate were more soluble in water than chlortetracycline hydrochloride, but the antibacterial activity was not enhanced. The influences of chlortetracycline hydrochloride, chlortetracycline bisulfate and chlortetracycline mesylate on chlortetracycline and immunoglobulin concentrations in mouse serum were also investigated. These results suggested that the chlortetracycline bisulfate and chlortetracycline mesylate have good bioavailability and strong immune response and have potential applications in animal breeding and formulation technologies.

Whole-cell paper strip biosensors to semi-quantify tetracycline antibiotics in environmental matrices

A novel, low-cost, and portable paper strip biosensor was developed for the detection of tetracycline antibiotics. Escherichia coli/pMTLacZ containing the tetracycline-mediated regulatory gene used as recognition elements with β-galactosidase as the reporter protein was designed and applied to cheap and portable Whatman filter paper as the carrier to prepare this paper strip biosensor. The detection process was optimized by using EDTA and polymyxin B as a sensitizer to improve the accuracy of detection for complicated matrices. The paper strip biosensor was suitable for tetracycline concentrations in the range of 75-10000 μg/L in water and 75-7500 μg/L in soil extracts. Detection limits of 5.23-17.1 μg/L for water and 5.21-35.3 μg/kg for the EDTA soil extracts were achieved at a response time of 90 min. The standard deviation (SD) of detected values by the biosensor paper strip compared to those determined by HPLC was between 13.4 and 59.6% for tetracycline and 2.01-33.5% for oxytetracycline in water and was between 6.22 and 72.8% for tetracycline and 5.90-43.4% for oxytetracycline in soil. This suggests that the paper strip biosensor was suitable for detecting both tetracycline and oxytetracycline in water, and could provide a suitable detection for extractable oxytetracycline in soils. Therefore, this biosensor provides a simple, economical, and portable piece of field kit for on-site monitoring of tetracyclines in a variety of environmental samples, such as pond water and agricultural soil that are susceptible to tetracycline pollution from feed additives and fertilization with livestock manure.

A Fast and Easily Parallelizable Biosensor Method for Measuring Extractable Tetracyclines in Soils

Quantification of extractable antibiotics in soils is important to assessing their bioavailability and mobility, and ultimately their ecotoxicological and health risks. This study aimed to establish a biosensor method for detecting extractable tetracyclines in soils (Alfisol, Mollisol, and Ultisol) using whole-cell biosensors containing a reporter plasmid (pMTGFP or pMTmCherry) carrying fluorescent protein genes tightly controlled by tetracyclines-responsive control region (tetRO). This whole-cell biosensor method can simultaneously measure 96 or more samples within 6 h and is easily parallelizable, whereas a typical high-performance liquid chromatography (HPLC) method may require 7 times more of analysis time and much greater cost to achieve similar analytical throughput. The biosensor method had a detection limit for each of six tetracyclines between 5.32-10.2 μg/kg soil, which is considered adequate for detecting tetracyclines in ethylenediaminetetraacetic acid (EDTA) extracts of soils. Relative standard deviation was between 19.8-51.2% for the biosensor Escherichia coli DH5α/pMTGFP and 2.98-25.8% for E. coli DH5α/pMTmCherry, respectively, suggesting that E. coli DH5α/pMTmCherry was superior to E. coli DH5α/pMTGFP for detecting extractable tetracyclines in soils. This new, fast, easily parallelizable, and cost-effective biosensor method has the potential for measuring extractable concentrations of tetracyclines for a large number of soil samples in large-scale monitoring studies.

Portable ratiometric probe based on the use of europium(III) coordination polymers doped with carbon dots for visual fluorometric determination of oxytetracycline

A novel ratiometric fluorescent probe for the determination of oxytetracycline (OTC) was developed. The method is based on the use of adenosine monophosphate/Eu(III) nanoscale coordination polymers doped with carbon dots (CDs) (CD@AMP/Eu NCPs). These were fabricated by self-assembly of Eu³⁺ and AMP on the surface of CDs containing large amounts of hydroxyl and carbonyl groups. Under the excitation at 310 nm wavelength, the doped NCPs display strong pink emission of Eu³⁺ at 615 nm and blue emission of the CDs at 430 nm on exposure to OTC. The ratio of fluorescence intensity (F₆₁₅/F₄₃₀) of such NCPs displays excellent linear relationship with OTC concentration ranging from 0.2 to 60 μM and the limit of detection (LOD) is 25 nM (3σ). The doped NCPs were evenly immobilized on common filter paper to prepare a visual ratiometric probe for the determination of OTC. Assisted by a digital camera with an APP color detector, the paper-based test strip was applied for the quantitative determination of OTC with a LOD of 0.5 μM and a wide linear scope of 1-100 μM. The method was applied to the determination of OTC in milk samples. Graphical abstractSchematic representation of the principle for oxytetracycline (OTC) determination using carbon dots (CD)@adenosine monophosphate (AMP)/Europium (Eu³⁺) paper-based ratiometic probe.

Effect of dissolved organic matter on adsorption of sediments to Oxytetracycline: An insight from zeta potential and DLVO theory

To reveal the adsorption mechanism of sediment to antibiotics with the presence of dissolved organic matter (DOM), batch experiments were carried out by oxytetracycline (OTC) on sediments with decayed plants (PDOM) and composted chicken manure (MDOM), and the zeta potential in the system before and after adsorption was measured. Results showed that the PDOM promoted the adsorption process, while the MDOM inhibited the adsorption. Adding PDOM, the change of zeta potential (Δζ) increased by 40.08% for first terrace sediments (FT) and 63.98% for riverbed sediments (RB), respectively; meanwhile, MDOM decreased by 20.04% for FT and 28.39% for RB, respectively. The results of kinetic fitting models of replacing the adsorption amount with Δζ were consistent with the initial. It indicated that there was a positive correlation between the adsorption amount and Δζ, and the zeta potential can be used to quickly judge the degree of adsorption process. The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory describes the interactions of sediment particles. In terms of adsorption amount, zeta potential (absolute value) and total interaction energy all followed the order: RB > FT, RB-PDOM > FT-PDOM, and RB-MDOM > FT-MDOM. The more negative the zeta potential is, the better the dispersion of the particles is. Stronger repulsion is more conducive to adsorbing positively charged OTC. The site energy distribution theory further explained that the distribution of adsorption site in the various states of sediments increased while adding the PDOM and decreased while adding the MDOM.

Analysis of the retention of tetracyclines on reversed-phase columns: Chemometrics, design of experiments and quantitative structure-property relationship (QSPR) study for interpretation and optimization

In this study, design of experiments was applied for the analysis of 6 reversed phase U-HPLC columns used for the separation of four tetracyclines (TCs): tetracycline, doxycycline, chlortetracycline and oxytetracycline in different elution conditions. In a first part, a fractional factorial design (2^4-1) was used to study the influence of four chromatographic parameters: column temperature, pH, flow rate and composition of the mobile phase (i.e. nature of the solvent used as the organic modifier), on the quality of the separation, which was evaluated in terms of peak width and resolution between two pairs of TCs. This experimental design revealed that the nature of the solvent: acetonitrile (ACN) or methanol (MeOH), and the mobile phase flow rate were the two main factors actually having the most influence on the quality of the separation. Moreover, these two factors presented an antagonistic influence according to the response considered: peak width or peak resolution. In order to understand this behavior, a Doehlert design was performed in the second part. It consisted in modeling the evolution of responses as a function of the two main factors: nature of the composition of the mobile phase (mix of ACN and MeOH, from 100% ACN to 100% MeOH) and mobile phase flow rate (from 0.3 to 0.8 mL min^-1). For all the reversed phase columns studied, an inversion of the elution order of TCs and an increase of the retention factors was observed according to the composition of the organic mixture at the end of the gradient. To understand the modification of the interactions implied in the various retention modes related to the selectivity of the organic solvents used, a quantitative structure-property relationship (QSPR) study was achieved. In this final study, the molecular descriptors of each TCs were connected to its retention factor.

An optimized sample treatment method for the determination of antibiotics in seawater, marine sediments and biological samples using LC-TOF/MS

Antibiotics used in marine aquaculture have been reported to accumulate in sediments and non-target aquatic organisms, modifying the biodiversity and the environmental conditions in areas close to the fish farms. Improved analytical methods are required to assess the spread and the impacts of aquaculture antibiotics in the marine environment, as well as to estimate resistance development risks. In this study, we have optimized a method for simultaneous quantitative determination of oxytetracycline, florfenicol and flumequine in marine samples using liquid chromatography coupled to time-of-flight high resolution mass spectrometry (LC-TOF/MS). The method optimization was carried out for seawater, sediment and biological samples (biofilm and two benthic invertebrate species: Gammarus aequicauda and Monodonta articulata). Special attention was paid to the optimization of the extraction and purification steps, testing: liquid-liquid and solid-liquid extractions, the use of silica and other commercial sorbents' clean-up, and single and tandem solid phase extraction procedures. The limits of quantification (MQLs) achieved with the developed method are 0.1-0.5 μg L-¹ in seawater; 1-5 μg kg^-1 in marine sediments; 5-25 μg kg^-1 in biofilm; and 100-500 μg kg^-1 in invertebrates, with good accuracy and precision. Method recoveries in spiked samples are 65-120% in seawater and sediment samples, and 63-110% in the biological samples. The method has been successfully implemented for the determination of antibiotic concentrations in sediment and invertebrate samples collected from a Mediterranean bay in south-east Spain. These represent significant advances in the analysis of antibiotics in environmental samples, especially for wild marine taxa, and attend for a proper assessment of the environmental fate and side effects of aquaculture antibiotics in the marine environment.

Removal of tetracycline from aqueous solution by MCM-41-zeolite A loaded nano zero valent iron: Synthesis, characteristic, adsorption performance and mechanism

In this study, nano zero valent iron (NZVI) modified MCM-41-zeolite A (Fe-MCM-41-A) composite as a novel adsorbent was prepared by precipitation method and applied for tetracycline (TC) removal from aqueous solution. The adsorbent was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and N₂-BET analysis. Hysteresis loops indicated that the sample has a desirable magnetic property and can be separated quickly. Adsorption studies were carried out to evaluate its potential for TC removal. Results showed that the optimal Fe-MCM-41-A dosage, initial pH and reaction time at initial TC concentration of 100mgL^-1 solution are 1gL^-1, pH=5, and 60 min respectively, at which the removal efficiency of TC was 98.7%. The TC adsorption results fitted the Langmuir isotherm model very well and the adsorption process could be described by a pseudo-second-order kinetic model. A maximum TC adsorption capacity of 526.32mgg^-1 was achieved. This study demonstrates that Fe-MCM-41-A is a promising and efficient material for TC adsorption from aqueous solution.

Occurrence, distribution, and attenuation of pharmaceuticals and personal care products in the riverside groundwater of the Beiyun River of Beijing, China

This study investigated the occurrence, seasonal-spatial distribution characteristics, and attenuation process of 15 pharmaceuticals and personal care products (PPCPs) in riverside sections of Beiyun River of Beijing. The overall PPCP levels both in surface water and riverside groundwater were moderate on the global scale, and showed higher concentrations in the dry season mainly caused by water temperature variation. Caffeine (CF), carbamazepine (CBZ), metoprolol (MTP), N,N-diethyl-meta-toluamide (DEET), diclofenac (DF), bezafibrate (BF), and gemfibrozil (GF) were seven representative PPCPs, because the rest eight studied compounds occurred in low concentrations and less than 15% of the total concentration of PPCPs. Caffeine and bezafibrate, respectively, was the most abundant compound in surface water and riverside groundwater, with median concentrations of 3020.0 and 125.0 ng L^-1. Total concentrations of PPCPs in surface water were much higher than those in the riverside groundwater spatially. Attenuation of PPCPs during riverbank filtration was largely depending on the sources, site hydrogeological conditions, and physical-chemical properties of PPCPs, also was influenced by dissolved organic matter and environmental physicochemical parameters. CF, MTP, DEET, and CBZ were potential groundwater attenuation contaminants; DF, BF, and GF were groundwater-enriched contaminants based on their removal rates. Predominant removal mechanism of PPCPs like CF was biodegradation. Attenuation simulation showed that the one-way supply between Beiyun River and riverside groundwater, and further confirmed Beiyun River, was the main source of pharmaceutical compounds in the riverside groundwater.

Migration and degradation of swine farm tetracyclines at the river catchment scale: Can the multi-pond system mitigate pollution risk to receiving rivers?

The study investigated the degradation behaviors of swine farm tetracyclines (TCs) at a catchment scale and explored whether multi-pond systems could be beneficial to the interception of TCs so as to reduce the pollution risk to receiving rivers. The occurrence and migration of 12 kinds of tetracycline antibiotics, including their degradation products, were studied in four swine farms of the Meijiang River basin in China. The migration paths of the TCs were examined through sampling and analyzing the soil and/or sediment at different points along the swine wastewater outlet, which included sewer, sewage pond, mixed-canal (stream and sewage), farmland (paddy and upland soil) and finally the river. TC concentrations of all collected samples were obtained by solid phase extraction followed by measurement with high-performance liquid chromatography tandem mass spectrometry. The results showed that sediment TC concentrations varied greatly in different swine farms, from mg·kg^-1 to μg·kg^-1 levels. TCs had different decay patterns along different migration paths, such that TCs decayed exponentially in paddy soil, while linearly in sewer and mixed canal. The concentrations of TCs and their degradation products decreased in the order: sewer sediment > sewage pond sediment > mixed-canal sediment > paddy soil > upland soil, indicating that TCs tend to be more easily intercepted and accumulated in water-sediment systems such as ponds. Therefore, the multi-pond system could be an effective way to prevent TCs from migrating into rivers. These results provided essential information for contamination control of antibiotics in aquatic environments.

Pharmaceuticals and personal care products (PPCPs) in urban and suburban rivers of Beijing, China: occurrence, source apportionment and potential ecological risk

This study analyzed 15 pharmaceuticals and personal care products (PPCPs) in two rivers with different urbanization levels in the surrounding watershed (urban and suburb) in Beijing, China. Along the rivers, effluent samples from wastewater treatment plants (WWTPs) and wastewater samples from direct discharge outlets were also collected to reveal their possible contribution to the occurrence of PPCPs in these two rivers. Among the 15 PPCPs, 14 compounds were detected with caffeine (maximum 11,900 ng L(-1)) being the dominant compound. The total concentration of the detected PPCPs in direct discharge outlets (median 4706 ng L(-1)) was much higher than that in river waters (2780 ng L(-1)) and WWTP effluents (1971 ng L(-1)). The suburban-influenced Liangshui River had significantly higher PPCP concentrations compared to the urban-influenced Qing River due to more input of untreated wastewater from direct discharge outlets. Source apportionment showed that approximately 55% of the total PPCPs were contributed by untreated wastewater in the suburban-influenced river. Finally, ecological risk assessment has been regarded as a necessary part of general research. According to the environmental risk assessment results, caffeine, trimethoprim and metoprolol were found to be the most critical compounds, due to their high risk quotient values. The results of the present study can provide useful information for future PPCP pollution control and sustainable water management in Beijing, China.

Enhancing Extraction and Detection of Veterinary Antibiotics in Solid and Liquid Fractions of Manure

Analysis of veterinary antibiotics in separated liquid and solid fractions of animal manures is vital because of wide variations in the composition of agriculturally applied manure. Differentiation of antibiotic concentrations is important between liquid and solid manures, as their sorption onto the solid fraction depends on physicochemical properties of each antibiotic and manure composition (e.g., organic content, pH) and because each fraction may be treated and reused differently. Here, an efficient and sensitive method for the analysis of 22 veterinary antibiotics in the liquid and solid fractions of manure is reported. Tetracycline (TC), macrolide, and sulfonamide antibiotics were extracted from liquid manure by liquid-liquid extraction (LLE) with methanol following acidification with acetic acid. Extraction from solids was performed by sonication with acetonitrile, methanol, and 0.1 M EDTA-McIlvaine buffer. Cleanup of extracts was achieved by solid-phase extraction with hydrophilic-lipophilic balance (HLB) cartridges or tandem amino (NH2) and HLB cartridges. Quantification of antibiotics was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) under wrong-way-round (WWR) ionization for sulfonamides and TCs and right-way-round ionization for macrolides. Recoveries of 58 to 94.7% and 62 to 94.3% were obtained in liquid and solid manure, respectively. Method detection limits range from 1.2 to 12 ng L and 0.5 to 7.9 μg kg dry wt. in liquids and solids, respectively. This method allows for extraction and analysis of both mobile antibiotics in liquid phase and hydrophobic antibiotics adsorbed on the solids. Without separate analysis, antibiotic concentrations may be improperly estimated by analyzing whole manure, as reported in many studies to date.

Optimization of sonochemical degradation of tetracycline in aqueous solution using sono-activated persulfate process

BACKGROUND

In this study, a central composite design (CCD) was used for modeling and optimizing the operation parameters such as pH, initial tetracycline and persulfate concentration and reaction time on the tetracycline degradation using sono-activated persulfate process. The effect of temperature, degradation kinetics and mineralization, were also investigated.

RESULTS

The results from CCD indicated that a quadratic model was appropriate to fit the experimental data (p < 0.0001) and maximum degradation of 95.01 % was predicted at pH = 10, persulfate concentration = 4 mM, initial tetracycline concentration = 30.05 mg/L, and reaction time = 119.99 min. Analysis of response surface plots revealed a significant positive effect of pH, persulfate concentration and reaction time, a negative effect of tetracycline concentration. The degradation process followed the pseudo-first-order kinetic. The activation energy value of 32.01 kJ/mol was obtained for US/S2O8 (2-) process. Under the optimum condition, the removal efficiency of COD and TOC reached to 72.8 % and 59.7 %, respectively. The changes of UV-Vis spectra during the process was investigated. The possible degradation pathway of tetracycline based on loses of N-methyl, hydroxyl, and amino groups was proposed.

CONCLUSIONS

This study indicated that sono-activated persulfate process was found to be a promising method for the degradation of tetracycline.

Immediate tooth replantation in rats: effect of systemic antibiotic therapy with amoxicillin and tetracycline

OBJECTIVES

The aim of this study was to evaluate the influence of systemic administration of antibiotics (amoxicillin and tetracycline) at the different phases of the repair process (7, 15, 30 days) in immediate rat tooth replantation.

MATERIALS AND METHODS

Ninety rats had their incisors extracted and stored in saline for 5 min. Next, the teeth were replanted, and the animals were assigned to three groups according to the antibiotic administered by oral gavage: control group, amoxycillin group, and tetracycline group. Euthanasia was performed at 7, 15, and 30 days after replantation.

RESULTS

Regardless of the evaluation period, the connective tissue underlying the epithelial attachment and the periodontal ligament showed statistically significant difference relative to the acute inflammatory infiltrate, which was more intense in the control group followed by the tetracycline group.

CONCLUSION

These results point to the fact that systemic antibiotic therapy (SAT) in immediate tooth replantation is beneficial to pulpal and periodontal ligament repair and that amoxycillin is an excellent option.

CLINICAL RELEVANCE

There is a lack of randomized studies assessing how the use of systemic antibiotics could influence tooth healing after immediate replantation.

Narrow grass hedges reduce tylosin and associated antimicrobial resistance genes in agricultural runoff

Agricultural runoff from areas receiving livestock manure can potentially contaminate surface water with antimicrobials and antimicrobial resistance genes (ARGs). The objective of this study was to investigate the effectiveness of narrow grass hedges (NGHs) on reducing the transport of antimicrobials and ARGs in runoff after land application of swine manure slurry. Plot-scale rainfall simulation tests were conducted on 0.75 m by 4.0 m plots designed to test three treatment factors: manure amendment (control plots receiving no manure vs. amended plots receiving manure based on 3 times N requirement), NGH (plots with a NGH vs. plots without a NGH), and rainfall events (days 1-3). Runoff generated during three 30-min simulated rainfall events was sampled and analyzed for antimicrobials and ARGs. Manure amendment was responsible for the presence of antimicrobial tylosin ( < 0.0001) and tylosin resistance gene (B) ( < 0.0001) in runoff. Narrow grass hedges proved to be effective in reducing tylosin ( < 0.0001) and (B) ( < 0.0347) in runoff. Manure amendment was responsible for the introduction of tylosin ( < 0.0482) and (B) ( = 0.0128) into the soil; however, it had no significant impact on the abundance of the 16S rRNA gene in soil. Results from this study suggest that NGHs could be a best management practice to control the transport of antimicrobials and ARGs in agricultural runoff.

Occurrence and source apportionment of pharmaceuticals and personal care products in the Beiyun River of Beijing, China

This work investigates, for the first time, the occurrence and sources of 15 pharmaceuticals and personal care products (PPCPs) in surface water of Beijing, one of most densely populated cities in the world, in three sampling events representing different seasonal flow conditions. The detection frequencies of most PPCPs were in the range of 50-100%. The median concentrations of the selected PPCPs ranged from not detected to 4200 ng L(-1) (caffeine). Generally, higher PPCP levels were observed in early spring, indicating both low flow condition and cold-water temperature might enhance their persistence. Source apportionment showed freshly discharged untreated sewage (67%) significantly contributed to the PPCP burden in the Beiyun River, which provides important information for environmental management.

Distribution and ecological risk of antibiotics in a typical effluent-receiving river (Wangyang River) in north China

In this study, the occurrence and distribution of sixteen antibiotics belonging to four groups in surface water, sediment and groundwater samples from the Wangyang River (WYR), a typical river receiving sewage discharges were investigated. Laboratory analyses revealed that antibiotics were widely distributed in the studied area. The aqueous samples were unavoidably contaminated with antibiotics, and the target antibiotics present in high levels were oxytetracycline, tetracycline, chlortetracycline, ofloxacin, sulfamethoxazole, and trimethoprim, with maximum concentrations of the individual contaminant at 3.6×10(5), 9.7×10(3), 6.9×10(4), 1.2×10(4), 4.8×10(3), and 1.1×10(3) ng L(-1), respectively. Oxytetracycline, tetracycline, ciprofloxacin and roxithromycin were the most frequently detected compounds in sediment samples, with maximum concentrations of the individual contaminant at 1.6×10(5), 1.7×10(4), 2.1×10(3) and 2.5×10(3) ng g(-1), respectively. The results also revealed that the high intensity of aquaculture activities could contribute to the increasing levels of antibiotics in the area. According to the ratios of measured environmental concentration (MEC) to predicted no-effect concentration (PNEC), chlortetracycline, tetracycline, ofloxacin, ciprofloxacin, erythromycin-H2O and sulfamethoxazole may present possible environmental risk to Pseudokirchneriella subcapitata, Synechococcus leopoliensis and M. aeruginosa. Attention should be given to the long-term ecological effects caused by the continuous discharge of antibiotics in the WYR area.

Occurrence, seasonal variation and risk assessment of antibiotics in the reservoirs in North China

The occurrence and seasonal variability of five groups (tetracycline, quinolone, chloramphenicol, macrolide and sulfonamide) of antibiotics were investigated in the surface water of four reservoirs. The dissolved concentrations of 29 antibiotics were in the ngL(-1) level. Trace levels of all target antibiotics were analyzed using solid-phase extraction followed by liquid chromatography electrospray tandem mass spectrometry. All of the antibiotics were detected at all sampling sites, indicating widespread occurrence of antibiotics in the study area. The detection of florfenicol, josamycin, kitasamycin, spiramycin and sulfameter is the first report of these compounds in reservoir samples. The results showed an association between the presence of some antibiotics at Panjiakou reservoir and cage culture of fish. Twenty-three types of antibiotics showed significant seasonal variations (p<0.001) due to human activities and flow conditions. A risk assessment showed that all antibiotics detected could cause very low risk to algae, daphnid and fish. Further health risk need to be investigated because these reservoirs are drinking water sources.

In-feed use of heavy metal micronutrients in U.S. swine production systems and its role in persistence of multidrug-resistant salmonellae

The study aimed to characterize the role of heavy metal micronutrients in swine feed in emergence of heavy-metal-tolerant and multidrug-resistant Salmonella organisms. We conducted a longitudinal study in 36 swine barns over a 2-year period. The feed and fecal levels of Cu(2+) and Zn(2+) were measured. Salmonella was isolated at early and late finishing. MICs of copper sulfate and zinc chloride were measured using agar dilution. Antimicrobial susceptibility was tested using the Kirby-Bauer method, and 283 isolates were serotyped. We amplified pcoA and czcD genes that encode Cu(2+) and Zn(2+) tolerance, respectively. Of the 283 isolates, 113 (48%) showed Cu(2+) tolerance at 24 mM and 164 (58%) showed Zn(2+) tolerance at 8 mM. In multivariate analysis, serotype and source of isolates were significantly associated with Cu(2+) tolerance (P < 0.001). Fecal isolates were more likely to be Cu(2+) tolerant than those of feed origin (odds ratio [OR], 27.0; 95% confidence interval [CI], 2.8 to 250; P = 0.0042) or environmental origin (OR, 5.8), implying the significance of gastrointestinal selective pressure. Salmonella enterica serotypes Typhimurium and Heidelberg, highly significant for public health, had higher odds of having >20 mM MICs of Cu(2+) than did "other" serotypes. More than 60% of Salmonella isolates with resistance type (R-type) AmStTeKm (32 of 53) carried pcoA; only 5% with R-type AmClStSuTe carried this gene. czcD gene carriage was significantly associated with a higher Zn(2+) MIC (P < 0.05). The odds of having a high Zn(2+) MIC (≥8 mM) were 14.66 times higher in isolates with R-type AmClStSuTe than in those with R-type AmStTeKm (P < 0.05). The findings demonstrate strong association between heavy metal tolerance and antimicrobial resistance, particularly among Salmonella serotypes important in public health.

Fate and transport of antimicrobials and antimicrobial resistance genes in soil and runoff following land application of swine manure slurry

Due to the use of antimicrobials in livestock production, residual antimicrobials and antimicrobial resistance genes (ARGs) could enter the environment following the land application of animal wastes and could further contaminate surface and groundwater. The objective of this study was to determine the effect of various manure land application methods on the fate and transport of antimicrobials and ARGs in soil and runoff following land application of swine manure slurry. Swine manure slurries were obtained from facilities housing pigs that were fed chlortetracyline, tylosin or bacitracin and were land applied via broadcast, incorporation, and injection methods. Three rainfall simulation tests were then performed on amended and control plots. Results show that land application methods had no statistically significant effect on the aqueous concentrations of antimicrobials in runoff. However, among the three application methods tested broadcast resulted in the highest total mass loading of antimicrobials in runoff from the three rainfall simulation tests. The aqueous concentrations of chlortetracyline and tylosin in runoff decreased in consecutive rainfall events, although the trend was only statistically significant for tylosin. For ARGs, broadcast resulted in significantly higher erm genes in runoff than did incorporation and injection methods. In soil, the effects of land application methods on the fate of antimicrobials in top soil were compound specific. No clear trend was observed in the ARG levels in soil, likely because different host cells may respond differently to the soil environments created by various land application methods.

Potential water quality impacts originating from land burial of cattle carcasses

Among the conventional disposal methods for livestock mortalities, on-farm burial is a preferred method, but the potential water quality impacts of animal carcass burial are not well understood. Typically, on-farm burial pits are constructed without liners and any leachate produced may infiltrate into soil and groundwater. To date, no information is available on temporal trends for contaminants in leachate produced from livestock mortality pits. In our study, we examined the concentrations of conventional contaminants including electrical conductivity, COD, TOC, TKN, TP, and solids, as well as veterinary antimicrobials and steroid hormones in leachate over a period of 20 months. Most of the contaminants were detected in leachate after 50 days of decomposition, reaching a peak concentration at approximately 200 days and declined to baseline levels by 400 days. The estrogen 17β-estradiol and a veterinary antimicrobial, monensin, were observed at maximum concentrations of 20,069 ng/L and 11,980 ng/L, respectively. Estimated mass loading of total steroid hormone and veterinary pharmaceuticals were determined to be 1.84 and 1.01 μg/kg of buried cattle carcass materials, respectively. These data indicate that leachate from carcass burial sites represents a potential source of nutrients, organics, and residues of biologically active micro-contaminants to soil and groundwater.

Sorption, Leaching, and Surface Runoff of Beef Cattle Veterinary Pharmaceuticals under Simulated Irrigated Pasture Conditions

The use of veterinary pharmaceuticals in beef cattle has led to concerns associated with the development of antibiotic resistance in bacteria and endocrine disruption in aquatic organisms. Despite the potential negative consequences, data on the transport and mitigation of pharmaceuticals in grazed watersheds with irrigated pasture are scarce. The objective of this study was to assess the transport of common beef cattle pharmaceuticals (oxytetracycline, chlortetracycline, and ivermectin) via surface runoff and leachate from manure amended to grass-vegetated soil boxes under irrigated pasture conditions. The transport of pharmaceuticals from animal manure in surface runoff and soil leachate was relatively low and appears to be limited by desorption and transport of pharmaceuticals entrained in the manure. In surface runoff, less than 4.2% of applied pharmaceuticals in manure (initial concentration: 0.2 mg kg of manure) was detected after 3 wk of irrigation. Concentrations of pharmaceuticals in surface runoff and leachate never exceeded 0.5 μg L. The major portion of pharmaceuticals (up to 99%) was retained in the manure or in the soil directly beneath the manure application site. Based on the minimal transport of oxytetracycline, chlortetracycline, and ivermectin, the risk of significant transport for these targeted beef cattle pharmaceuticals to surface water and groundwater from manure on irrigated pasture appears to be relatively low.