Determination of antibiotic compounds in water by solid-phase extraction-high-performance liquid chromatography-(electrospray) 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.

Encapsulating functionalized graphene quantum dot into metal-organic framework as a ratiometric fluorescent nanoprobe for doxycycline sensing

A distinctive fluorescent nanoprobe with the function of doxycycline identification was designed by encapsulating histidine and serine-functionalized graphene quantum dots (His-GQDs-Ser) into the luminescent metal-organic frameworks (MOF). The synthesized nanoprobe displayed the merits of prominent selectivity, wide detection range, and high sensitivity. The interaction of doxycycline and the fabricated fluorescent nanoprobe contributed to the phenomenon of the suppression of the fluorescence of the His-GQDs-Ser and enhancement of the MOF fluorescence. Linear relation between the concentration of doxycycline and the ratio fluorescence intensity of the nanoprobe was observed, which evidenced the brilliant capability in the ranges 0.003-6.25 μM and 6.25-25 μM with a detection limit of 1.8 nM. Additionally, the practicability of the probe was verified in analysis of spiked milk sample, and the satisfactory recoveries of doxycycline varied from 97.39 to 103.61%, with relative standard deviations in the range 0.62-1.42%. A proportional fluorescence sensor for doxycycline detection in standard solution was constructed, which provides a potential for the development of other fluorescence detection systems.

The antibacterials ciprofloxacin, trimethoprim and sulfadiazine modulate gene expression, biomarkers and metabolites associated with stress and growth in gilthead sea bream (Sparus aurata)

The high consumption and subsequent input of antibacterial compounds in marine ecosystems has become a worldwide problem. Their continuous presence in these ecosystems allows a direct interaction with aquatic organisms and can cause negative effects over time. The objective of the present study was to evaluate the effects of exposure to three antibacterial compounds of high consumption and presence in marine ecosystems (Ciprofloxacin CIP, Sulfadiazine SULF and Trimethoprim TRIM) on the physiology of the gilthead sea bream, Sparus aurata. Plasma parameters, enzymatic biomarkers of oxidative stress and damage and expression of genes related to stress and growth were assessed in exposed S. aurata specimens. For this purpose, sea bream specimens were exposed to individual compounds at concentrations of 5.2 ± 2.1 μg L^-1 for CIP, 3.8 ± 2.7 μg L^-1 for SULF and 25.7 ± 10.8 μg L^-1 for TRIM during 21 days. Exposure to CIP up-regulated transcription of genes associated with the hypothalamic-pituitary-thyroid (HPT) (thyrotropin-releasing hormone, trh) and hypothalamic-pituitary-interrenal (HPI) axes (corticotropin-releasing hormone-binding protein, crhbp) in the brain, as well as altering several hepatic stress biomarkers (catalase, CAT; glutathione reductase, GR; and lipid peroxidation, LPO). Similar alterations at the hepatic level were observed after exposure to TRIM. Overall, our study indicates that S. aurata is vulnerable to environmentally relevant concentrations of CIP and TRIM and that their exposure could lead to a stress situation, altering the activity of antioxidant defense mechanisms as well as the activity of HPT and HPI axes.

Long-Term Study of Antibiotic Presence in Ebro River Basin (Spain): Identification of the Emission Sources

Water monitoring is key to determining the presence of potentially hazardous substances related to urban activities and intensive farming. This research aimed to perform a long-term (four years) quantitative monitoring of selected antibiotics (azithromycin, enrofloxacin, trimethoprim and sulfadiazine) both in rivers and wastewaters belonging to the Ebro River basin (North of Spain). The target antibiotics were chosen on the basis of a preliminary multispecies screening. The analysis of the antibiotics was carried out by LC-MS/MS on wastewater-treatment plant (WWTP) effluent, effluents of a slaughterhouse and hospital, rivers downstream and upstream of these WWTPs, and rivers close to extensive farming areas. The ANOVA test was performed to study the significant differences between the points exposed to concrete emission sources and antibiotic concentration. The monitoring, carried out from 2018 to 2020, has been essential to illustrating the presence of the most abundant antibiotics that were detected in the Ebro River basin. Enrofloxacin has appeared in river waters in significant concentrations, especially near intensive farming, meanwhile azithromycin has been frequently detected in wastewaters.

Fully-automated SPE coupled to UHPLC-MS/MS method for multiresidue analysis of 26 trace antibiotics in environmental waters: SPE optimization and method validation

Achieving simultaneous determination of antibiotic multiresidues in environmental waters by solid phase extraction (SPE) coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) with detection limits ≤ ng L^-1 is still a huge challenge. Moreover, the offline SPE procedure was performed manually, costly, and time-consuming, while the online SPE required precision pretreatment instruments that require highly-skilled personnel. In this paper, a fully automated SPE coupled with UHPLC-MS/MS method was developed for analysis of antibiotics (sulfonamides, quinolones, and macrolides) in water matrices. Sample preparation optimization included SPE materials and configuration (HLB disks), sample volume (500-1000 mL), and pH (pH = 3) with a flow rate at 2~5 mL min^-1, and an elution procedure with 2 × 6 mL methanol, and 2 × 6 mL acetone. Meanwhile, the parameters for UHPLC-MS/S detection of analytes were optimized, including LC retention time, and MS parameters. The instrumental limits of detection (LOD) and quantification (LOQ) of analytes ranged from 0.01-0.72 μg L^-1 and 0.05-2.39 μg L^-1, respectively, with satisfactory linear calibration (R² > 0.995) and precision (< 9.9%). Recoveries in spike samples ranged between 77.5-104.9% in pure water, 59.4-97.8% in surface water (SW), and 58.2-108.6% in wastewater effluent (WWE) with relative standard deviations ≤ 12.8%. The matrix effects observed for most analytes were suppression (0-28.1%) except for five analytes having presented enhancement (0-14.6 %) in SW or WWE. This method can basically meet the needs of trace antibiotic residues detection in waters, with examples of concentrations of detected antibiotics being lower than LOQ (LLQ) -94.47 ng L^-1 in WWEs and LLQ-15.47 ng L^-1 in SW in the lower reaches of the Yangtze River Basin.

Toxicity of fluoroquinolones on the cladoceran Daphnia magna

This study evaluates the acute and chronic toxicological effects of six fluoroquinolones on the mortality and growth of Daphnia magna. The NOECs calculated with the multivariate Probit regression model for the chronic study were 56 μg/L ciprofloxacin, 63 μg/L enrofloxacin, 78 μg/L levofloxacin, 85 μg/L marbofloxacin, 69 μg/L norfloxacin, and 141 μg/L ofloxacin. The risk quotients were determined using the measure environmental concentrations reported in water sources from different countries. The risks were low and moderate in water samples from rivers and lakes, although concentrations of ciprofloxacin, norfloxacin, and ofloxacin reported in some countries can cause toxicological damage to D. magna. In addition, urban wastewater and hospital wastewater samples constitute a threat to D. magna (high and moderate risks), requiring the treatment of these wastewater. PRACTITIONER POINTS: The NOECs calculated with the multivariate Probit model for the six fluoroquinolonas are between 56 μg/L ciprofloxacin and 141 μg/L ofloxacin. The levels of ciprofloxacin, norfloxacin, and ofloxacin in urban wastewater and hospital wastewater produce moderate and high risks for D. magna. Water and river samples from some countries containing ciprofloxacin, norlfoxacin, and ofloxacin present high risks for D. magna.

Antibiotics in the aquatic environments: A review of lakes, China

The potential threat of antibiotics to the environment and human health has raised significant concerns in recent years. The consumption and production of antibiotics in China are the highest in the world due to its rapid economic development and huge population, possibly resulting in the high detection frequencies and concentrations of antibiotics in aquatic environments of China. As a water resource, lakes in China play an important role in sustainable economic and social development. Understanding the current state of antibiotics in lakes in China is important. Closed and semi-closed lakes provide an ideal medium for the accumulation of antibiotics and antibiotic resistance genes (ARGs). This review summarizes the current levels of antibiotic exposure in relevant environmental compartments in lakes. The ecological and health risks of antibiotics are also evaluated. This review concludes that 39 antibiotics have been detected in the aquatic environments of lakes in China. The levels of antibiotic contamination in lakes in China is relatively high on the global scale. Antibiotic contamination is higher in sediment than water and aquatic organisms. Quinolone antibiotics (QNs) pose the greatest risks. The contents of antibiotics in aquatic organisms are far lower than their maximum residual limits (MRLs), with the exception of the organisms in Honghu Lake. The lakes experience high levels of ARG contamination. A greater assessment of ARG presence and antibiotic exposure are urgent.

Activated carbon adsorption of quinolone antibiotics in water: Performance, mechanism, and modeling

The extensive use of antibiotics has led to their presence in the aquatic environment, and introduces potential impacts on human and ecological health. The capability of powdered activated carbon (PAC) to remove six frequently used quinolone (QN) antibiotics during water treatment was evaluated to improve drinking water safety. The kinetics of QN adsorption by PAC was best described by a pseudo second-order equation, and the adsorption capacity was well described by the Freundlich isotherm equation. Isotherms measured at different pH showed that hydrophobic interaction, electrostatic interaction, and π-π dispersion force were the main mechanisms for adsorption of QNs by PAC. A pH-dependent isotherm model based on the Freundlich equation was developed to predict the adsorption capacity of QNs by PAC at different pH values. This model had excellent prediction capabilities under different laboratory scenarios. Small relative standard derivations (RSDs), i.e., 0.59%-0.92% for ciprofloxacin and 0.09%-3.89% for enrofloxacin, were observed for equilibrium concentrations above the 0.3mg/L level. The RSDs increased to 11.9% for ciprofloxacin and 32.1% for enrofloxacin at μg/L equilibrium levels, which is still acceptable. This model could be applied to predict the adsorption of other chemicals having different ionized forms.

Rapid and Sensitive Detection of Bacteria Response to Antibiotics Using Nanoporous Membrane and Graphene Quantum Dot (GQDs)-Based Electrochemical Biosensors

The wide abuse of antibiotics has accelerated bacterial multiresistance, which means there is a need to develop tools for rapid detection and characterization of bacterial response to antibiotics in the management of infections. In the study, an electrochemical biosensor based on nanoporous alumina membrane and graphene quantum dots (GQDs) was developed for bacterial response to antibiotics detection. Anti-Salmonella antibody was conjugated with amino-modified GQDs by glutaraldehyde and immobilized on silanized nanoporous alumina membranes for Salmonella bacteria capture. The impedance signals across nanoporous membranes could monitor the capture of bacteria on nanoporous membranes as well as bacterial response to antibiotics. This nanoporous membrane and GQD-based electrochemical biosensor achieved rapid detection of bacterial response to antibiotics within 30 min, and the detection limit could reach the pM level. It was capable of investigating the response of bacteria exposed to antibiotics much more rapidly and conveniently than traditional tools. The capability of studying the dynamic effects of antibiotics on bacteria has potential applications in the field of monitoring disease therapy, detecting comprehensive food safety hazards and even life in hostile environment.

Sensitive Monitoring of Fluoroquinolones in Milk and Honey Using Multiple Monolithic Fiber Solid-Phase Microextraction Coupled to Liquid Chromatography Tandem Mass Spectrometry

In the present study, a new multiple monolithic fiber solid-phase microextraction (MMF-SPME) based on poly(apronal-co-divinylbenzene/ethylenedimethacrylate) monolith (APDE) was synthesized. The effect of the preparation parameters of APED on extraction efficiency was studied thoroughly. The combination of APDE/MMF-SPME with high-performance liquid chromatography tandem mass spectrometry detection (HPLC/MS-MS) was developed for sensitive monitoring of ultratrace fluoroquinolones (FQs) in foodstuffs, including milk and honey samples. Under the optimized experimental conditions, the limits of detection (S/N = 3) for the targeted FQs ranged from 0.0019 to 0.018 μg/kg in milk and 0.0010 to 0.0028 μg/kg in honey. The relative standard deviations (RSDs) for method reproducibility were less than 9% in all samples. The established method was successfully applied for the monitoring of FQs residues in milk and honey samples with the recoveries between 74.5% and 116% (RSDs were in the range 0.9-9.5%). In comparison to previous methods, the developed APDE/MMF-SPME-HPLC/MS-MS showed some merits, including satisfactory sensitivity, simplicity, high cost-effectiveness, and low consumption of organic solvent.

Remediation of pharmaceuticals and personal care products using an aerobic granular sludge sequencing bioreactor and microbial community profiling using Solexa sequencing technology analysis

Recently, a new type of organic pollution derived from pharmaceuticals and personal care products (PPCPs) is gradually on the rise. Wastewater treatment to remove PPCPs was investigated using an aerobic granular sludge sequencing bioreactor (GSBR). After optimization of influent organic load, hydraulic shear stress, sludge settling time, etc., aerobic granular sludge was analyzed for its physiological and biochemical characteristics and tested for its efficacy to remove PPCPs wastewater. The granular sludge effectively removed some but not all of the PPCPs tested; removal correlated with the microbial profiles in the granules, as assessed using Solexa sequencing technology. Sequencing revealed the presence of five phylogenetic groups: Proteobacteria, Bacteroidetes, Betaproteobacteria, an unclassified genus, and Zoogloea. The results demonstrated changes in the microbial profiles with time in response to the presence of PPCPs. The effects of PPCPs on microbial communities in granular sludge process are discussed.

Fluoroquinolone antibiotics: an emerging class of environmental micropollutants

The aim of this review paper is to provide a comprehensive overview of different chemical and environmental aspects concerning fluoroquinolone antibiotics as emerging contaminants. A literature survey has been performed based on 204 papers from 1998 to mid-2013, resulting in a dataset consisting out of 4100 data points related to physical-chemical properties, environmental occurrence, removal efficiencies, and ecotoxicological data. In a first part, an overview is given on relevant physical-chemical parameters to better understand the behavior of fluoroquinolones during wastewater treatment and in the environment. Secondly, the route of these antibiotics after their application in both human and veterinary surroundings is discussed. Thirdly, the occurrence of fluoroquinolone residues is discussed for different environmental matrices. The final part of this review provides a tentative risk assessment of fluoroquinolone compounds and their transformation products in surface waters by means of hazard quotients. Overall, this review shows that fluoroquinolone antibiotics have a wide spread use and that their behavior during wastewater treatment is complex with an incomplete removal. As a result, it is observed that these biorecalcitrant compounds are present in different environmental matrices at potentially hazardous concentrations for the aquatic environment. The latter calls for actions on both the consumption as well as the wastewater treatment aspect to diminish the discharge of these biological active compounds.

A qualitative survey of five antibiotics in a water treatment plant in central plateau of Iran

Introduction. This study aimed to survey a total of five common human and veterinary antibiotics based on SPE-LC-MS-MS technology in a water treatment plant at central plateau of Iran. Also two sampling techniques, passive and grab samplings, were compared in the detection of selected antibiotics. Materials and Methods. In January to March 2012, grab and passive samples were taken from the influent and effluent of a water treatment plant. The samples were prepared using solid-phase extraction (SPE), and extracts were analyzed by liquid chromatography tandem mass spectrometry (LC-MS-MS). Results. The results showed that enrofloxacin, oxytetracycline, and tylosin were not detected in none of the samples. However, ampicillin was detected in the grab and passive samples taken from the influent (source water) of the plant, and ciprofloxacin was detected in passive samples taken from the influent and effluent (finished water) of the plant. Conclusion. The results imply that passive sampling is a better approach than grab sampling for the investigation of antibiotics in aquatic environments. The presence of ampicillin and ciprofloxacin in source water and finished water of the water treatment plant may lead to potential emergence of resistant bacteria that should be considered in future studies.

Chlortetracycline degradation by photocatalytic ozonation in the aqueous phase: mineralization and the effects on biodegradability

Chlortetracycline (CTC) is a hazardous material in aquatic environments. This study was focused on optimization of photocatalytic ozonation processes for removal of CTC from wastewater at pH 2.2 and 7.0. In this study, the tested processes for CTC removal were arranged from the least efficient to the most efficient as: UV, UV/TiO2, O3, O3/UV and O3/UV/TiO2. Ozonation efficiency was due to ozone affinity for electron-rich sites on the CTC molecule. In the O3/UV and O3/UV/TiO2 processes, efficiency was increased by the photolysis of CTC and generation of *OH. At pH 7.0, all the processes were more efficient for CTC degradation than at pH 2.2 due to CTC speciation, ozone decay to *OH and the attractions between ionized CTC and TiO2 particles. UV/O3 at pH 7.0 showed an additive effect while other combination processes showed a synergistic effect that resulted in higher rates of reactions than the sums of individual reaction rates. The TOC removal ranged from 8% to 41% after one hour of reaction, with the above-mentioned order of efficiency. The biodegradability increased rapidly during the early minutes of the reaction. A reaction time of 10-15 min was sufficient for near maximum biodegradability, making these processes good pretreatments for the biological processes.

Antibiotics pollution in Jiulong River estuary: source, distribution and bacterial resistance

To gain insight into the antibiotic pollution in the Jiulong River estuary and the pollutant sources, we analyzed the concentration of 22 widely-used antibiotics in water samples collected from the river and estuary, 17 and 18 sampling sites, respectively. Contamination with sulfonamides, quinolones and chloramphenicols was frequently detected and the distribution pattern of antibiotics suggested that most of the pollutants are from the Jiulong River, especially from the downstream watersheds. To reveal the ecological effects, we isolated 35 bacterial strains from the estuary and analyzed their antibiotic resistance to the eight most frequently detected antibiotics. The bacteria were subsequently classified into seven different genera by 16SrDNA sequencing. Up to 97.1% of the bacteria showed resistance and 70.6% of strains showed multi-resistance to these antibiotics, especially to sulfonamides. This study demonstrated a pattern of antibiotic contamination in the Jiulong River and its estuary and illustrated high bacterial antibiotic resistance which was significantly correlated with the average antibiotics concentrations and detected frequencies in the estuary.

Occurrence and risk assessment of four typical fluoroquinolone antibiotics in raw and treated sewage and in receiving waters in Hangzhou, China

A sensitive liquid chromatography-fluorescence detection method, combined with one-step solid-phase extraction, was established for detecting the residual levels of the four typical fluoroquinolone antibiotics (ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin) in influent, effluent, and surface waters from Hangzhou, China. For the various environmental water matrices, the overall recoveries were from 76.8 to 122%, and no obvious interferences of matrix effect were observed. The limit of quantitation of this method was estimated to be 17 ng/L for ciprofloxacin and norfloxacin, 20 ng/L for ofloxacin, and 27 ng/L for enrofloxacin. All of the four typical fluoroquinolone antibiotics were found in the wastewaters and surface waters. The residual contents of the four typical fluoroquinolone antibiotics in influent, effluent, and surface water samples are 108-1405, 54-429, and 7.0-51.6 ng/L, respectively. The removal rates of the selected fluoroquinolone antibiotics were 69.5 (ofloxacin), 61.3 (norfloxacin), and 50% (enrofloxacin), indicating that activated sludge treatment is effective except for ciprofloxacin and necessary to remove these fluoroquinolone antibiotics in municipal sewage. The risk to the aquatic environment was estimated by a ratio of measured environmental concentration and predicted no-effect concentration. At the concentrations, these fluoroquinolone antibiotics were found in influent, effluent, and surface waters, and they should not pose a risk for the aquatic environment.

Tetracycline degradation by ozonation in the aqueous phase: proposed degradation intermediates and pathway

During the ozonation of tetracycline (TC) in aqueous media at pHs 2.2 and 7.0, the effects of pH variations, protonation and dissociation of functional groups and variation in free radical exposure were investigated to elucidate the transformation pathway. Liquid chromatography-triple quadrupole mass spectrometry detected around 15 ozonation products, and uncovered their production and subsequent degradation patterns. During ozonation at pH 2.2, the TC degradation pathway was proposed on the basis of the structure, ozonation chemistry and mass spectrometry data of TC. Ozonation of TC at the C11a-C12 and C2-C3 double bonds, aromatic ring and amino group generated products of m/z 461, 477, 509 and 416, respectively. Further ozonation at the above mentioned sites gave products of m/z 432, 480, 448, 525 and 496. The removal of TOC reached a maximum of approximately 40% after 2 h of ozonation, while TC was completely removed within 4-6 min at both pHs. The low TOC removal efficiency might be due to the generation of recalcitrant products and the low ozone supply for high TC concentration. Ozonation decreased the acute toxicity of TC faster at pH 7.0 than pH 2.2, but the maximum decrease was only about 40% at both pHs after 2 h of ozonation. In this study, attempts were made to understand the correlation between the transformation products, pathway, acute toxicity and quantity of residual organics in solution. Overall, ozonation was found to be a promising process for removing TC and the products initially generated.

Appraisal of potential environmental risks associated with human antibiotic consumption in Turkey

A comprehensive analysis of Turkish antibiotic data was conducted to evaluate potential environmental risks associated with antibiotic consumption in Turkey for year 2007. Antibiotics were defined for systemic use or group J01 of the WHO Anatomical Therapeutic Chemical (ATC) classification system. Total emissions and prescriptions for each ATC group were classified separately into 17 different J01 categories and three forms of medication (capsule/tablets, injectables and suspensions). Capsules and tablets were found as the most emitted form of medication in year 2007, with a total emission rate of about 585.5 tons/year (76%). Total antibiotic emission rates including all forms of medications were determined to be about 664.2 tons/year (86%) and 110.1 tons/year (14%) for adult and pediatric patients, respectively. An environmental risk assessment of 8 human antibiotics was conducted according to the EU draft guidance (CEC/III/5504/94, draft 6, version 4) and the risk was indicated by the ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) for the aquatic environment. Available acute and chronic toxicity data were collected from the open peer-reviewed literature to derive PNEC. Risk quotients (PEC/PNEC) were then calculated for 8 pharmaceutical substances. PEC/PNEC ratio exceeded 1.0 for beta-lactams (cephalosporins and penicillins), fluoroquinolones, macrolides and aminoglycosides. The findings of this study concluded that the release of these compounds from wastewater treatment plants may potentially be of an important environmental concern based on today's use of antibiotics in Turkey.

Chlortetracycline and tylosin runoff from soils treated with antimicrobial containing manure

This study assessed the runoff potential of tylosin and chlortetracycline (CTC) from soils treated with manure from swine fed rations containing the highest labeled rate of each chemical. Slurry manures from the swine contained either CTC at 108 microg/g or tylosin at 0.3 microg/g. These manures were surface applied to clay loam, silty clay loam, and silt loam soils at a rate of 0.22 Mg/ha. In one trial, tylosin was applied directly to the soil surface to examine runoff potential of water and chemical when manure was not present. Water was applied using a sprinkler infiltrometer 24-hr after manure application with runoff collected incrementally every 5 min for about 45 min. A biofilm crust formed on all manure-treated surfaces and infiltration was impeded with > 70% of the applied water collected as runoff. The total amount of CTC collected ranged from 0.9 to 3.5% of the amount applied whereas tylosin ranged from 8.4 to 12%. These data indicate that if surface-applied manure contains antimicrobials, runoff could lead to offsite contamination.

Degradation of tetracycline and oxytetracycline by crude lignin peroxidase prepared from Phanerochaete chrysosporium--a white rot fungus

Pharmaceuticals are becoming an emerging environmental issue that attracts increasing attention in recent years. This study chose tetracycline (TC) and oxytetracycline (OTC) as examples of pharmaceuticals. Crude lignin peroxidase (LiP) produced by Phanerochaete chrysosporium were used to degrade TC and OTC in vitro. The results illustrated that LiP has a strong degrading ability towards TC and OTC. At 50 mgL(-1) of TC and OTC and 40 UL(-1) of the enzyme activity, the degradation of TC and OTC reached to about 95% in 5 min. The degradation of TC and OTC by LiP was dependent on pH and temperature and was largely enhanced by increasing the concentrations of veratryl alcohol (VA) and initial hydrogen peroxide (H2O2). The optimized degradation conditions were determined as pH 4.2, 37 degrees C, 2 mM VA, 0.4 mM H2O2.

Simultaneous determination of macrolides, sulfonamides, and other pharmaceuticals in water samples by solid-phase extraction and LC-(ESI) MS

This paper describes a method for determining 11 pharmaceuticals in various water sources by SPE followed by LC-(ESI) MS. SPE was carried out with Oasis HLB and the recoveries were 33-67% for 250 and 100 mL sewage water, 55-77% for 500 mL river water and 72-98% for 1 L tap water, with the exception of sulfamethoxazole and omeprazole which showed lower recoveries in all kinds of sample. The LODs in river water were of 5 ng/L for sulfadiazine, trimethoprim, sulfamethazine, sulfamethoxazole, and ranitidine and 10 ng/L for the other compounds. The highest concentrations found in river waters were for sulfamethoxazole (50 ng/L). In influent sewage waters, ranitidine was the most commonly detected compound with a maximum value of 0.24 microg/L.

Determination of photoirradiated tetracyclines in water by high-performance liquid chromatography with chemiluminescence detection based reaction of rhodamine B with cerium (IV)

A simple, selective and sensitive method has been developed for the simultaneous determination of tetracycline, oxytetracycline, chlorotetracycline, demeclocycline, doxycycline and meclocycline based on reversed-phase high-performance liquid chromatography with chemiluminescence detection. The procedure was based on the chemiluminescent enhancement by photoirradiated tetracyclines of the cerium (IV)-rhodamine B system in sulphuric acid medium. The six tetracyclines were separated on an Aquasil-C18 column with a gradient elution using a mixture of acetonitrile and 0.1 mol L(-1) phosphate buffer as mobile phase, photoderivatized using a photoreactor consisting of a tube reactor coil of PFA and a 8W Xenon lamp. Under the optimized conditions, the method was validated with respect to linearity, precision, limits of detection and quantification and accuracy. The relative standard deviation (RSD) on intra-day precision was below 10% and detection limits ranged between 0.12 and 0.34 microg L(-1). The proposed method has been successfully applied to the determination of tetracyclines in surface water samples. A possible mechanism of the chemiluminescence in the system is discussed.