Green method by National Environmental Methods Index and Eco-Scale Assessment for evaluation of gatifloxacin-based product by HPLC.

The literature reveals gaps in the availability of green analytical methods for assessing products containing gatifloxacin (GFX), a fluoroquinolone. Presently, method development is supported by tools such as the National Environmental Methods Index (NEMI) and Eco-Scale Assessment (ESA), which offer objective insights into the environmental friendliness of analytical procedures. The objective of this work was to develop and validate a green method by the NEMI and ESA to quantify GFX in eye drops using HPLC. The method utilized a C8 column (4.6 × 150 mm, 5 µm), with a mobile phase of purified water containing 2% acetic acid and ethanol (70:30, v/v). The injection volume was 10 µL and the flow rate was 0.7 mL/min in isocratic mode at 25°C, with detection performed at 292 nm. The method demonstrated linearity in the range of 2-20 µg/mL, and precision at intra-day (relative standard deviation [RSD] 1.44%), inter-day (RSD 3.45%), and inter-analyst (RSD 2.04%) levels. It was selective regarding the adjuvants of the final product (eye drops) and under forced degradation conditions. The method was accurate (recovery 101.07%) and robust. The retention time for GFX was approximately 3.5 min. The greenness of the method, as evaluated by the NEMI, showed four green quadrants, and by ESA, it achieved a score of 88.

Antibiotics in sewage treatment plants, receiving water bodies and groundwater of Chennai city and the suburb, South India: Occurrence, removal efficiencies, and risk assessment.

The presence of antibiotics in the aqueous environment can alter the water microbiome, inducing antimicrobial resistance genes. Hence, the occurrence of 18 antibiotics belonging to sulfonamides, fluoroquinolones, tetracyclines, phenicols, and macrolides classes were investigated in surface water, groundwater, and sewage treatment plants in Chennai city and the suburbs. Fluoroquinolones had the maximum detection frequency in both influent and effluent samples of urban and suburban STPs, with ofloxacin and ciprofloxacin showing the highest influent concentrations. Erythromycin was the predominant antibiotic in surface water samples with an average concentration of 194.4 ng/L. All the detected antibiotic concentrations were higher in the Buckingham Canal compared to those in Adyar and Cooum rivers, possibly due to direct sewer outfalls in the canal. In groundwater samples, ciprofloxacin showed the highest levels with an average of 20.48 ng/L and the concentrations were comparable to those of surface water. The average sulfamethazine concentration in groundwater (5.2 ng/L) was found to be slightly higher than that of the surface water and much higher than the STP influent concentrations. High levels of ciprofloxacin and sulfamethazine in groundwater may be because of their high solubility and wide use. Moreover, erythromycin was completely removed after treatment in urban STPs; FQs showed relatively lesser removal efficiency (2.4-54%) in urban STPs and (8-44%) in suburban STP. Tetracyclines and phenicols were not detected in any of the samples. Ciprofloxacin and azithromycin in surface water pose a high risk in terms of estimated antibiotic resistance. This study revealed that the measured surface water concentration of antibiotics were 500 times higher for some compounds than the predicted calculated concentrations from STP effluents. Therefore, we suspect the direct sewage outlets or open drains might play an important role in contaminating surface water bodies in Chennai city.

Antibiotics in the Basque coast (N Spain): Occurrence in waste and receiving waters, and risk assessment (2017-2020).

The study of the presence of antibiotics in the aquatic environment is a preliminary step to analyse their possible harmful effects on aquatic ecosystems. In order to monitor their occurrence in the aquatic environment, the European Commission established in 2015, 2018, and 2020 three Watch Lists of substances for Union-wide monitoring (Decisions (EU) 2015/495, 2018/840, and 2020/1161), where some antibiotics within the classes of macrolides, fluoroquinolones and penicillins were included. In the Basque coast, northern Spain, three macrolide antibiotics (erythromycin, clarithromycin, azithromycin) and ciprofloxacin were monitored quarterly from 2017 to 2020 (covering a period before and after the COVID19 outbreak), in water samples collected from two Waste Water Treatment Plants (WWTPs), and three control points associated with receiving waters (transitional and coastal water bodies). This work was undertaken for the Basque Water Agency (URA). The three macrolide antibiotics in water showed a frequency of quantification >65 % in the Basque coast, with higher concentrations in the WWTP emission stations than in receiving waters. Their frequency of quantification decreased from 2017 to 2020, as did the consumption of antibiotics in Spanish primary care since 2015. Ciprofloxacin showed higher frequencies of quantification in receiving waters than in wastewaters, but the highest concentrations were observed in the WWTP emission stations. Although consumption of fluoroquinolones (among which is ciprofloxacin) in primary care in the Basque Country has decreased in recent years, this trend was not observed in the waters sampled in the present study. On the other hand, concentrations of clarithromycin, azithromycin, and ciprofloxacin in receiving waters exceeded their respective Predicted No-Effect Concentrations, so they could pose an environmental risk. These substances are widely used in human and animal medicine, so, although only ciprofloxacin is included in the third Watch List, it would be advisable to continue monitoring macrolides in the Basque coast as well.

Photodegradation of fluoroquinolones in aqueous solution under light conditions relevant to surface waters, toxicity assessment of photoproduct mixtures.

Photochemical degradation of fluoroquinolones ciprofloxacin, enrofloxacin and norfloxacin in aqueous solution under light conditions relevant to surface waters at neutral and alkaline pH was found to proceed readily with half-lives between 0.9 and 2.7 min. The products of photochemical degradation identified by HPLC-MS included defluorinated, hydroxylated, and decarboxylated structures as well as structures with opened cyclic structures. For all of the studied substances, the reaction pathways were influenced significantly by the pH of the reaction system, with more products formed at alkaline pH than at neutral pH: the ratios of products in neutral and alkaline pH were 16/26, 9/19, 15/23 for ciprofloxacin, enrofloxacin, and norfloxacin, respectively. The structures of photoproducts and pathways of photochemical degradation are proposed. The antibacterial activities of photoproduct mixtures tested on E. coli and S. epidermidis were significantly higher in comparison to parental antibiotics in the case of both ciprofloxacin and enrofloxacin with p-values less than 0.0001 in most cases. The effect of the photoproducts was shown to be dependent on the pH value of the original antibiotic solutions before photodegradation: for ciprofloxacin, antibacterial activity against E. coli was more notably pronounced with regard to neutral pH photoproducts, while a less significant, or in one case not significant, effect of pH was observed against S. epidermidis; for norfloxacin, antibacterial activity against both E. coli and S. epidermidis was especially high with regard to alkaline pH photoproducts.

Occurrence and risk assessment of fluoroquinolone antibiotics in reclaimed water and receiving groundwater with different replenishment pathways.

Artificial recharge to groundwater with reclaimed water is considered a promising method to alleviate groundwater depletion and over-exploitation. However, the occurrence of fluoroquinolone antibiotics (FQs) was ubiquitous in wastewater, surface water, groundwater and even drinking water threating human health and ecology. In this study, the occurrence of six selected FQs in reclaimed water effluent and their removal by tertiary treatment units were investigated. The overall removal efficiencies in average of the tertiary treatment processes in Beijing and Changzhou were ranging from 21.2% to 55.2%. Activated carbon exhibited better performance for FQs removal than ozone and biological treatment such as membrane bioreactor, anaerobic-anoxic-oxic and biofilter. The results of two pilot study showed that the impact of reclaimed water to groundwater quality in terms of FQs concentration by direct injection in GBD was stronger than surface spreading in Changzhou, which might be due to the recharge strategy and the physical and chemical characteristics of sediment and aquifer soil. The hazard quotient (HQ) values of ofloxacin (OFL) in reclaimed water was up to 12.54, indicating the extreme eco-toxicological risk, while enrofloxacin (ENR) exhibited medium risk. After recharge with reclaimed water, the HQ values of OFL and ENR in groundwater ranged from low to medium ecological risk to the environment. Thus, the FQs in reclaimed water need to be paid more attention during their reuse for groundwater recharge, especially by direct injection. It is suggested that FQs should be considered in the priority substances lists in standards and guidelines of reclaimed water reuse for groundwater recharge to ensure the safety of groundwater.

Occurrence and Risk Assessment of Antibiotics in Manure, Soil, Wastewater, Groundwater from Livestock and Poultry Farms in Xuzhou, China.

Antibiotics in manure, soil, wastewater, and groundwater samples from the livestock and poultry farms in Xuzhou City were investigated in the present study. The concentrations of antibiotics in all matrices varied greatly among farms. Total concentrations of fluoroquinolones and macrolides were much higher than those of sulfonamides in manures and soil samples. Total concentrations of antibiotics in wastewater of livestock farms were higher than those of poultry farm. Josamycin (JM) and tilmicosin (TIL) accounted for more than 74% of the nine macrolides in all groundwater samples. Sulfamethizole (SMT), fleroxacin (FLE), cinoxacin (CIN) and JM were the main antibiotics detected in manure and soil samples, while sulfamethoxypyridazine (SMP), sulfameter (SME), SMT, FLE, JM and TIL accounted for a large proportion of antibiotics in surface and groundwater. The risk assessment of target antibiotics revealed that JM in wastewater showed relatively high RQs for aquatic organisms.

Investigation of antibiotics in sea cucumbers: occurrence, pollution characteristics, and human risk assessment.

Occurrence and distribution of 24 antibiotics from 7 categories were screened in sea cucumbers (Echinodermata: Holothuroidea) collected from different coastal regions of China. The samples were simultaneously extracted and purified using accelerated solvent extraction with in-cell clean-up and analyzed by ultra-performance liquid chromatography-tandem mass spectrometry. A total of ten antibiotics were detected in the sea cucumbers with concentrations ranging from not detected to 32.8 µg/kg (dry weight). Sulfonamides are predominant antibiotics with a mean concentration of 11.5 µg/kg (dry weight), followed by macrolides (11.3 µg/kg, dry weight) and fluoroquinolones (11.2 µg/kg, dry weight). High concentrations of the antibiotics were found in the samples from the South China Sea, implying that the antibiotic pollution in sea cucumbers was geographical region-dependent, which was further confirmed by principal component analysis. It was also found that the antibiotic levels are slightly higher in instant sea cucumbers than in the dried ones. Hazard quotient calculation suggested no obvious human health risks associated with the consumption of sea cucumbers regarding antibiotics.

Risk assessment of fluoroquinolones from poultry muscle consumption: Comparing healthy adult and pre-school populations.

Antibiotics, especially fluoroquinolones (FQs), have been largely used in animal husbandry namely poultry production. Therefore, this study aimed to identify, quantify and estimate the daily intake for adult and 3-year-old populations of the FQs norfloxacin (NOR), ciprofloxacin (CIP) and enrofloxacin (ENR) through poultry muscle consumption. The results showed detection frequencies of 78% and 62% in supermarket and school canteen samples, respectively. Of the 182 analysed samples, 4 did not comply with ENR maximum residue level (MRL), and 9 were contaminated with NOR, not allowed as a veterinary medicine of food-producing animals. The highest estimated daily intake value was obtained for the 3-year-old population regarding the sum of ENR and CIP (0.46 µg kg-1 day-1); value substantially lower than the established acceptable daily intake (2.0 µg kg-1 day-1). Although the low risk found, the high detection frequencies support the apprehension of the different international organizations, towards the emergence of human bacterial resistances to FQs originated from poultry production.

Antibiotics in surface water and sediments from Hanjiang River, Central China: Occurrence, behavior and risk assessment.

Thirteen antibiotics including sulfonamides (SAs), tetracyclines (TETs) and fluoroquinolones (FQs) were measured in Hanjiang River (HR) during two periods. The total concentrations of 13 antibiotics in surface water and sediments ranged from 3.1 to 109 ng/l and from 10 to 45 ng/g dry weight, respectively. SAs were dominant in water while the concentrations of TETs were the highest in sediments in two seasons. For their spatial distribution, total concentrations of 13 antibiotics in both matrices were significantly higher in the lower section of HR (p < 0.02, F > 5.15) due to wastewater release, agricultural activities and water transfer project. Obvious seasonal variations of sulfadiazine, sulfameter, trimethoprim and oxytetracycline in water were observed (p < 0.05, F > 4.62). Phase partition of antibiotics between water and sediments suggested a greater affinity of TETs and FQs to sediments. In addition, significantly positive relationships were found between SAs (sulfameter, sulfamethoxazole and trimethoprim) and sediment TOC (p < 0.05). Risk assessment indicated that the hazard quotients of antibiotics were higher in the sediment than those in the water. Moreover, antibiotic mixtures posed higher ecological risks to aquatic organisms.

An effervescence-assisted switchable fatty acid-based microextraction with solidification of floating organic droplet for determination of fluoroquinolones and tetracyclines in seawater, sediment, and seafood.

This study developed a new effervescence-assisted switchable fatty acid-based microextraction combined with solidification of a floating organic-droplet (EA-SFAM-SFO) for simple and rapid determination of fluoroquinolones and tetracyclines in seawater, sediment, and seafood. Five medium-chain fatty acids (pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, and nonanoic acid) were tested as an extraction solvent, given their ability to change between hydrophobic and hydrophilic forms by pH adjustment. As nonanoic acid had the highest extraction recovery (>92%) for the six antibiotics and the ability to transform from liquid to a solidified floating state at low temperature, it was selected as the optimum extraction solvent. The prominent advantages of the newly developed method are: (1) reaction between the procedures salt and fatty acid changed extraction solvent from the hydrophobic to hydrophilic state; (2) bubbling with CO2 greatly increased the contact area between fatty acid and analytes resulting in improved extraction recovery; and (3) solidification of the fatty acid at a low temperature provided good separation and avoided the use of specialized equipment. Single-factor screening and optimization of the main factors were conducted using Plackett-Burman design and central composite design, respectively. The main parameters were optimized as follows: 258 µL fatty acid, 406 µL H2SO4 (98%), 3.9 min vortex time, and 354 µL Na2CO3 (2 mol L-1). Under optimized conditions, limits of detection were 0.007-0.113 µg L-1 or µg kg-1 and extraction recoveries were 82.2%-116.7% for six fluoroquinolone and tetracycline antibiotics in seawater, sediments, and seafood. The newly developed method combines the advantages of effervescence-assisted dispersion, hydrophobic/hydrophilic switchable solvent, and liquid/solid transition induced by low temperature. Overall, the new method is simple, quick, and environment-friendly with low detection limits and high recoveries. Thus, the newly developed method has excellent prospects for sample pretreatment and analysis of antibiotics in marine environmental and food samples. Graphical Abstract ᅟ.

Occurrence and risk assessment of fluoroquinolones and tetracyclines in cultured fish from a coastal region of northern China.

Occurrence and levels of 11 fluoroquinolones (FQs) and four tetracyclines (TC) in 14 cultured fish species from a coastal city in the northern China were investigated. Five FQs (ofloxacin, enoxacin, ciprofloxacin, enrofloxacin, and sarafloxacin) and oxytetracycline were detected. Lower detection frequencies of antibiotics were observed in the marine fish. The concentrations of ΣFQs ranged from not detectable (nd) to 130 ng/g wet weight (ww) (median, 7.2 ng/g ww), and the concentration range of ΣTCs was nd to 200 ng/g ww (median, nd ng/g ww). The Chinese snakehead contained the highest concentrations of ΣFQs (130 ng/g ww) and the small yellow croaker accumulated the highest concentrations of ΣTCs (200 ng/g ww), respectively. Although the calculated estimated daily intakes (EDI) suggested that the consumption of these cultured fish from this region was not associated with significant human health risks, this study provides useful information that will be helpful in the appropriate antibiotic use in aquaculture. To our knowledge, this can be the first report on the occurrence and levels of antibiotics in cage-cultured marine fish from the Bohai Rim region, China.

Determination and health risk assessment of enrofloxacin, flumequine and sulfamethoxazole in imported Pangasius catfish products in Thailand.

The goals of this study were to determine the levels of three antibiotics - enrofloxacin, flumequine and sulfamethoxazole - in Pangasius catfish products imported into Thailand and to assess the health risks from consumption. To extract these antibiotic residues, acetonitrile, methanol and a small amount of formic acid were used as solvents. Determination of the antibiotics after extraction steps was carried out by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) technique. The results showed that 14 and 3 samples of Pangasius catfish products were contaminated with enrofloxacin and sulfamethoxazole, respectively. No flumequine residue was found. While the concentration levels of these antibiotics in most contaminated samples were lower than the European Union (EU) standard, one sample was found to contain sulfamethoxazole at 245.91 µg kg-1, which was higher than the EU standard (100 µg kg-1), indicating the likelihood that some contaminated freshwater fish products are widely distributed in Thai markets. Notably, the concentration levels of enrofloxacin in samples of Pangasius catfish with skin were higher than in non-skin products, suggesting that products with skin might retain more antibiotic residues than non-skin products. Although the hazard quotient showed that consuming imported Pangasius catfish products, based on the current consumption rate, will not adversely affect consumer health, antibiotic residues in Pangasius catfish products imported into Thailand should be continually monitored.

Rapid in vivo determination of fluoroquinolones in cultured puffer fish (Takifugu obscurus) muscle by solid-phase microextraction coupled with liquid chromatography-tandem mass spectrometry.

Fluoroquinolones (FQs) are a group of antimicrobial agents that have been widely used for therapeutic purposes in clinical medicine for human and veterinary diseases, as well as in aquaculture production. Their residues, however, may survive in foods of animal origin, thus causing health risks for human. In this study, a rapid and sensitive method based on in vivo solid-phase microextraction (SPME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to detect the residues of five FQs in cultured puffer fish (Takifugu obscurus). In vitro fiber evaluation experiment demonstrated that, compared with the thicker polydimethylsiloxane (PDMS) coating (165µm), the custom-made biocompatible C18-PAN fibers (45µm) exhibited much higher extraction efficiencies towards FQs (approximately 9-31 times). The custom-made C18-PAN coating also possessed excellent reproducibility in fish muscle with the intra-fiber relative standard deviations (RSDs) ranging from 11.2% to 14.3% (n = 6) and inter-fiber RSDs ranging from 13.1% to 16.1% (n = 6), which was suitable for in vivo sampling. The custom-made SPME fibers were subsequently applied to determine fluoroquinolones in dorsal-epaxial muscle of living puffer fish. The accuracies were verified through the comparison with traditional liquid extraction (LE) method, and the sensitivities were demonstrated to be satisfying with the limits of detection (LODs) ranging from 0.3ngg-1 to 1.5ngg-1. In general, this study presented a convenient and high-efficient method to determine fluoroquinolones in puffer fish by in vivo sampling.

Assessment of soils contamination with veterinary antibiotic residues in Northern Poland using developed MAE-SPE-LC/MS/MS methods.

Among the wide range of compounds reaching the soil are the veterinary antimicrobials. Since no regulations regarding acceptable levels of drug concentrations in the environment exist, monitoring tests, particularly concerning soils, are carried out very rarely. This study presents a preliminary assessment of the contamination of agricultural soils in Northern Poland with seven antimicrobial veterinary medicines which has never been carried out before. Veterinary drugs were detected in 54% of the examined soil samples; the most commonly detected drugs were sulfonamides and trimethoprim. The highest indicated concentrations refer to enrofloxacin (57.0 µg kg-1) and trimethoprim (47.8 µg kg-1). The presence of these target drugs in the soil environment confirms the need for further monitoring studies. The analytical methods developed in this study are an excellent tool to achieve this goal and allow an estimation of the risk connected with the presence of veterinary antimicrobials in soils.

Occurrence and human dietary assessment of fluoroquinolones antibiotics in cultured fish around tai lake, China.

Fluoroquinolone antibiotics are widely used in the production of aquatic products and considered to be a significant contributing factor to the burden of both natural and aquaculture environments. However, the main types of fluoroquinolones present in aquaculture systems have not been determined. The objectives of the present study were to explore the occurrence of residual fluoroquinolone antibiotics in fish muscle tissues sampled from across the entire aquaculture season in the Tai Lake basin in China and to assess the dietary risks associated with the upcoming vendible fish in the last month of the aquaculture season. Fluoroquinolones were detected in 95.69% of all fish samples, and the concentrations ranged from the limit of quantification (LOQ) to 47 108.00 µg · kg-1 . Enrofloxacin contributed the most among the 9 fluoroquinolone antibiotics tested. Of the 4 fish species studied, enrofloxacin was present in bream at significant (p < 0.05) concentrations in August, with an average value of 321.45 µg · kg-1 , while enrofloxacin concentrations peaked in crab and shrimp in September, with average values of 6949.60 and 460.82 µg · kg-1 , respectively. However, different patterns were observed in perch, suggesting that other categories of antibiotics may be used in the production of this fish. Dietary risk assessment showed that the residual levels and estimated daily intake in bream, perch, and shrimp were far below the maximum residual level and acceptable daily intake. However, the average residual level in crab exceeded the maximum residual level, and the estimated daily intake value accounted for 78.49% of the acceptable daily intake, indicating potential consumption risk. In summary, the present study aims to guide the production and consumption of aquatic products. Environ Toxicol Chem 2017;36:2899-2905. © 2017 SETAC.

Pharmacokinetics, milk penetration and PK/PD analysis by Monte Carlo simulation of marbofloxacin, after intravenous and intramuscular administration to lactating goats.

The main objectives of this study were (i) to evaluate the serum pharmacokinetic behaviour and milk penetration of marbofloxacin (MFX; 5 mg/kg), after intravenous (IV) and intramuscular (IM) administration in lactating goats and simulate a multidose regimen on steady-state conditions, (ii) to determine the minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) of coagulase negative staphylococci (CNS) isolated from caprine mastitis in Córdoba, Argentina and (iii) to make a PK/PD analysis by Monte Carlo simulation from steady-state pharmacokinetic parameters of MFX by IV and IM routes to evaluate the efficacy and risk of the emergence of resistance. The study was carried out with six healthy, female, adult Anglo Nubian lactating goats. Marbofloxacin was administered at 5 mg/kg bw by IV and IM route. Serum and milk concentrations of MFX were determined with HPLC/uv. From 106 regional strains of CNS isolated from caprine mastitis in herds from Córdoba, Argentina, MICs and MPCs were determined. MIC90 and MPC90 were 0.4 and 6.4 µg/ml, respectively. MIC and MPC-based PK/PD analysis by Monte Carlo simulation indicates that IV and IM administration of MFX in lactating goats may not be adequate to recommend it as an empirical therapy against CNS, because the most exigent endpoints were not reached. Moreover, this dose regimen could increase the probability of selecting mutants and resulting in emergence of resistance. Based on the results of Monte Carlo simulation, the optimal dose of MFX to achieve an adequate antimicrobial efficacy should be 10 mg/kg, but it is important take into account that fluoroquinolones are substrates of efflux pumps, and this fact may determine that assumption of linear pharmacokinetics at high doses of MFX may be incorrect.

Facile and fast preparation of low-cost silica-supported graphitic carbon nitride for solid-phase extraction of fluoroquinolone drugs from environmental waters.

The analytical application of silica-supported graphitic carbon nitride (g-C3N4@silica) for solid-phase extraction (SPE) of fluoroquinolone (FQ) pollutants from water is presented for the first time. g-C3N4@silica was easily and quickly prepared by one-pot thermal condensation of dicyandiamide and characterized by powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy and surface area measurements. The novel composite was applied as sorbent for SPE of FQs from water prior high-performance liquid chromatography with fluorescence detection. The extraction efficiency of g-C3N4 was tested in tap and surface waters at actual concentrations (10-100ngL-1). Quantitative adsorption was achieved using 100mg sorbent (20wt% g-C3N4) for pre-concentration of 50-500mL sample, at the native pH (∼7.5-8). Elution was performed with 25mM H3PO4 aqueous solution-acetonitrile (80:20), obtaining recoveries in the range 70-114%, enrichment factors up to 500 and inter-day RSDs≤12%. The batch-to-batch reproducibility was assessed on three independently synthesized g-C3N4@silica preparations (RSD 6-12%). g-C3N4 supported on silica microparticles proved to be of easy preparation, inexpensive, reusable for at least 4 extractions of raw surface waters, and suitable for determination in real matrices.

Distribution and Risk Assessment of Antibiotics in a Typical River in North China Plain.

We evaluated the occurrence and distribution of 12 antibiotics from the sulfonamide (SAs), fluoroquinolone (FQs) and tetracycline (TCs) groups in the Weihe River, North China. The total antibiotic concentrations in surface water, pore water, and sediment samples ranged from 11.1 to 173.1 ng/L, 5.8 to 103.9 ng/L, and 9.5 to 153.4 µg/kg, respectively. The values of the sediment-water partitioning coefficient in the Weihe River varied widely, from not detected to 943, 2213, and 2405 L/kg for SAs, FQs, and TCs, respectively. The values of the partitioning coefficients between sediment and surface water were generally lower than those between sediment and pore water, which indicated ongoing inputs to the water. The risk assessment showed that there were relatively high ecological risks to aquatic algae in this area from sulfamethoxazole, norfloxacin, tetracycline, ofloxacin, and ciprofloxacin.

Occurrence and risk assessment of antibiotics in surface water and groundwater from different depths of aquifers: A case study at Jianghan Plain, central China.

The occurrence of 14 antibiotics (fluoroquinolones, tetracyclines, macrolides and sulfonamides) in groundwater and surface water at Jianghan Plain was investigated during three seasons. The total concentrations of target compounds in the water samples were higher in spring than those in summer and winter. Erythromycin was the predominant antibiotic in surface water samples with an average value of 1.60µg/L, 0.772µg/L and 0.546µg/L respectively in spring, summer and winter. In groundwater samples, fluoroquinolones and tetracyclines accounted for the dominant proportion of total antibiotic residues. The vertical distributions of total antibiotics in groundwater samples from three different depths boreholes (10m, 25m, and 50m) exhibited irregular fluctuations. Consistently decreasing of antibiotic residues with increasing of depth was observed in four (G01, G02, G03 and G05) groundwater sampling sites over three seasons. However, at the sampling sites G07 and G08, the pronounced high concentrations of total antibiotic residues were detected in water samples from 50m deep boreholes instead of those at upper aquifer in winter sampling campaign, with the total concentrations of 0.201µg/L and 0.100µg/L respectively. The environmental risks posed by the 14 antibiotics were assessed by using the methods of risk quotient and mixture risk quotient for algae, daphnids and fish in surface water and groundwater. The results suggested that algae might be the aquatic organism most sensitive to the antibiotics, with the highest risk levels posed by erythromycin in surface water and by ciprofloxacin in groundwater among the 14 antibiotics. In addition, the comparison between detected antibiotics in groundwater samples and the reported effective concentrations of antibiotics on denitrification by denitrifying bacteria, indicating this biogeochemical process driven by microorganisms won't be inhibitory influenced by the antibiotic residues in groundwater.

A new simple electrochemical Moxifloxacin Hydrochloride sensor built on carbon paste modified with silver nanoparticles.

A new sensitive simple electrochemical sensor for Moxifloxacin Hydrochloride (MOXI) detection has been successfully performed. The sensor built on carbon paste (CP) modified with silver nanoparticles (AgNPs). AgNPs are biocompatible stable noble materials especially in biological sensing. The silver nanoparticles modified carbon paste electrode (SNMCPE) displayed high electrocatalytic activity towards oxidation of 1.0mM MOXI in Britton Robinson (BR) buffer of pH range (2.0-9.0). The techniques used to do this work are cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Surface characteristics were achieved using scanning electron microscopic (SEM) and Energy Dispersive X-Ray Analysis (EDX) techniques. The effect of changing MOXI concentration (7.0×10-7 to 1.8×10-4M) was studied in BR buffer (pH =7.4) at a scan rate of 50mV/s using SNMCPE. The detection and quantification limits were found to be 2.9×10-9M and 9.6×10-8M, respectively. In order to assess the applicability of MOXI detection method in real samples; this method was tested in Delmoxa tablet and human urine sample. Good sensible results were attained for MOXI detection.