Ionic Liquid-Functionalized Magnetic Metal-Organic Framework Nanocomposites for Efficient Extraction and Sensitive Detection of Fluoroquinolone Antibiotics in Environmental Water

Herein, the hydrophobic carboxyl-functionalized ionic liquid (IL-COOH) was encapsulated into the prepared Fe₃O₄@Zr-MOFs, and the novel water-stable IL-COOH/Fe₃O₄@Zr-MOF nanocomposites were first synthesized. The polydopamine-functionalized Fe₃O₄ was introduced to construct the core-shell structure via layer-by-layer modification, and the controlled growth of Zr-MOFs was achieved, which realized the adjustment of charged properties of nanocomposites and simplified the adsorption or extraction process. The IL-COOH/Fe₃O₄@Zr-MOFs were fully studied by IR, HNMR, XRD, N₂ adsorption-desorption isotherms, TEM, EDS mapping, VSM, and so on. Then, they were employed for the selective adsorption and detection of fluoroquinolone antibiotics (FQs). The adsorption isotherms and kinetics demonstrated that the adsorption process followed a pseudo-second-order kinetic model and the Langmuir isotherm model. Among them, IL-COOH/Fe₃O₄@UiO-67-bpydc showed the best adsorption performance, and the maximum adsorption capacity of ofloxacin was 438.5 mg g^-1. Coupled magnetic solid-phase extraction with HPLC-DAD, a convenient, sensitive, and efficient method for extraction and detection of FQs in environmental water, was developed based on IL-COOH/Fe₃O₄@UiO-67-bpydc. The recoveries of environmental water were ranging from 90.0 to 110.0%, and the detection limits were lower than 0.02 μg L^-1. The novel functionalized composites served as solid-phase adsorbents and liquid-phase extractants. This study also provided a promising strategy for designing and preparing multi-functionalized nanocomposites for the removal or detection of pollutants in environmental samples.

Facile synthesis of magnetic sulfonated covalent organic framework composites for simultaneous dispersive solid-phase extraction and determination of β-agonists and fluoroquinolones in food samples

In this work, an efficient method for the determination of β-agonists and fluoroquinolones was established, based on a mixed-mode sorbent of magnetic sulfonated covalent organic framework composites. By coupling with HPLC-MS/MS, the main factors that affect the extraction procedure were optimized. Under the optimal conditions, the proposed HPLC-MS/MS method was successfully utilized for the extraction of β-agonists and fluoroquinolones in milk and pork meat samples. The method showed good linearities (R² ≥ 0.9916), and low LOQs of 0.1-0.2 ng g^-1 for β-agonists and fluoroquinolones. The adsorption mechanism was investigated with the assistance of quantum chemistry calculation method, and it is worth noting that the sorbent relied mainly on the multiple adsorption mechanisms, including π-π stacking, hydrophobic, electrostatic attraction and hydrogen-bonding interactions. This work not only provides a simple method for the preparation of a mixed-mode sorbent, but also a routine analysis strategy for monitoring the illegal use of β-agonists and fluoroquinolones.

Portable Smartphone-Based QDs for the Visual Onsite Monitoring of Fluoroquinolone Antibiotics in Actual Food and Environmental Samples

Accurate onsite profiling of fluoroquinolone antibiotics (FQs) is of vital significance for ensuring food safety and estimating environmental pollution. Here, we propose a smartphone-based QD ratiometric fluorescence-sensing system to precisely report the level of FQs. As a proof of concept, we chose gatifloxacin (GFLX, a typical member of FQs) as the model for the analytical target, which could effectively trigger the fluorescence color variation of QDs from bright yellow-green (∼557 nm) to blue (∼448 nm) through the photoinduced electron-transfer (PET) process, thus yielding an evident ratiometric response. Based on this, the level of GFLX can be reported within a wide linear range from 0.85 nM to 3.6 μM. Moreover, this assay owns a high sensitivity with a low detection limit of 0.26 nM for GFLX and a quick sample-to-answer monitoring time of 5.0 min, manifesting that this platform could be fully qualified for onsite requirements. Interestingly, this portable device has successfully been applied for the onsite detection of GFLX in real food (i.e., milk and drinking water) and environmental (i.e., fish-farming water) samples with acceptable results. This developed platform offers a great promise for the point-of-care detection of FQ residues in practical application with the merits of being label-free, low-cost, and rapid, thus opening a new pathway for the onsite evaluation of food safety and environmental health.

Antibiotics and Resistance Genes in Awash River Basin, Ethiopia

Among contaminants of emerging concern in the environment, a growing attention has been given to antibiotics and antibiotic-resistant genes (ARGs) due to the rise in their usage and potential ecotoxicological and public health effect. However, the occurrence of these contaminants in the environment is little investigated in developing countries particularly in sub-Saharan regions. In this study, the occurrence of three groups of antimicrobials including tetracycline, sulfonamides and fluoroquinolone, and their corresponding ARGs were investigated in the sediments of Awash River Basin, Ethiopia. Out of twelve studied compounds, sulfadiazine and enrofloxacin showed the highest and lowest detection frequency, respectively. Polymerase chain reaction (PCR) analysis revealed that tetA and tetB occurred in all the samples. The relative abundance of the resistant genes was in the following order: tetA > tetB > sul2 > sul1. Redundancy analysis result indicated that some sediment characteristics were found to have influence on the distribution sul1-resistant gene.

High-Throughput and High-Efficient Micro-solid Phase Extraction Based on Sulfonated-Polyaniline/Polyacrylonitrile Nanofiber Mats for Determination of Fluoroquinolones in Animal-Origin Foods

We herein describe a high-throughput 96-well plate micro-solid phase extraction sample preparation technique based on novel sulfonated-polyaniline/polyacrylonitrile nanofiber mats (sulfonated-PANI/PAN NFMs) for multiresidue detection of fluoroquinolones (FQs) in various animal-origin food samples. Through the double-modification of polyaniline and sulfonic acid, the resulting functionalized sulfonated-PANI/PAN NFMs present high extraction efficiency for FQs. Compared with the existing methods, this approach demonstrates its advantages of being suitable for more sample matrices (milk, animal muscle, liver, kidney, and egg), lower sample amount (0.5 g), lower sorbent requirement (5.0 mg), lower volume of organic solvent (0.7 mL), shorter time (0.2 min per sample), and high sensitivity (0.012-0.06 μg·kg^-1). In addition, sulfonated-PANI/PAN NFMs possess excellent reusability which could be reused 10 times without an obvious decrease in extraction efficiency. Combined with ultra performance liquid chromatography-tandem mass spectrometry, the novel sample preparation technique can be expected as an efficient method for routine trace FQ residue monitoring in animal-origin food samples.

Optimization of process conditions for preparation of activated carbon from waste Salix psammophila and its adsorption behavior on fluoroquinolone antibiotics

Salix psammophila (SP), a solid waste abundantly available, was applied as a precursor to prepare the activated carbon by chemical activation method using phosphoric acid (H₃PO₄). Response surface methodology based on Box-Behnken design was used to optimize the prepared conditions of activated carbon. The effects of concentration of H₃PO₄, activation temperature and activation time on the adsorption performance (expressed by the adsorption capacity of ciprofloxacin hydrochloride (CIP) and norfloxacin (NOR)) were investigated. The optimum conditions were obtained using H₃PO₄ concentration of 67.83%, activation temperature of 567.44 °C and activation time of 86.61 min. The optimum activated carbon (SPAC) was characterized with scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FTIR). The adsorption behavior of CIP and NOR on SPAC was carried out and the mechanisms for the adsorption process were proposed. The equilibrium data were fitted by the Freundlich and Langmuir isotherm models, which resulted in 251.9 mg/g and 366.9 mg/g of the maximum monolayer adsorption for CIP and NOR at 25 °C, respectively. The best fitted kinetic model was pseudo-second-order, implying that chemisorption dominated in the adsorption process. This study indicated that activated carbon based on Salix psammophila (SPAC) was an excellent adsorbent for removing fluoroquinolone antibiotics from aqueous solutions.

Highly Stable Zr(IV)-Based Porphyrinic Metal-Organic Frameworks as an Adsorbent for the Effective Removal of Gatifloxacin from Aqueous Solution

Water stable Zr-metal–organic framework nanoparticles (PCN-224 NPs, PCN refers to porous coordination network) have been solvothermally synthesized. PCN-224 NPs show spherical shape with smooth surface and particle size of approximately 200 nm. PCN-224 NPs can be stable in acid and aqueous solutions, as confirmed by powder X-ray diffraction. Gatifloxacin (GTF) adsorption measurements showed that PCN-224 NPs exhibit a high adsorption capacity of 876 mg·g⁻¹. Meanwhile, the adsorption factors, adsorption characteristics, and mechanisms of GTF were investigated in batch adsorption experiments.

Synergistic effect of aqueous removal of fluoroquinolones by a combined use of peroxymonosulfate and ferrate(VI)

This paper examines for the first time the combined use of ferrate(VI) (Fe^VIO₄^2-, Fe(VI)) with peroxymonosulfate (PMS) to oxidize four fluoroquinolones (FQs) (flumequine (FLU), enrofloxacin (ENR), marbofloxacin (MAR), and ofloxacin (OFL)) at pH 7.0 and 25.0 °C. The results demonstrate that a combination of PMS and Fe(VI) synergistically enhance removal of FQs compared to the removal seen with either PMS or Fe(VI) alone. The oxidized products (OPs) of the reaction of FLU with the PMS-Fe(VI) system, identified by liquid chromatography high-resolution mass spectrometry (LC-HRMS) techniques, showed transformation products resulted from hydroxylation, ring cleavage, and de-fluorination processes. Thus, the combination of PMS and Fe(VI) can be developed as an innovative oxidative technology to remove contaminants from water.

Oxidation of ciprofloxacin and enrofloxacin by ferrate(VI): Products identification, and toxicity evaluation

Ferrate(VI) (Fe(VI)) has been known to react with emerging organic contaminants containing electron-rich organic moieties, such as phenols, anilines, olefins, reduced sulfur and deprotonated amines. Oxidation of fluoroquinolone antibiotics, ciprofloxacin (CIP) and enrofloxacin (ENR), by Fe(VI) were investigated for their reaction products and toxicity changes as well as biodegradability of these products. Ten products were identified for both CIP and ENR reactions with Fe(VI) using a high-resolution accurate-mass Orbitrap mass analyzer. Structural changes to the CIP and ENR molecule included dealkylation, formation of alcohols and amides in piperazine ring and oxygen transfer to the double bond in quinolone structure. An enamine formation mechanism was tentatively proposed to facilitate the interpretation of CIP and ENR oxidation pathways. Toxicity evaluation using Microbial Assay for toxicity Risk Assessment (MARA) bioassay indicated that Fe(VI) oxidation products of CIP and ENR contributed negligible antibacterial potency and Fe(VI) oxidation treatment can remove the residual toxicity of CIP and ENR impacted source waters. The Fe(VI) oxidation treatment resulted in formation of relatively more biodegradable products (based on in silico assessment) than their corresponding parent compounds. The results showed that Fe(VI) has a good potential to degrade fluoroquinolone antibiotics and their antimicrobial potency in natural waters.

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.

Evaluation of the Presence and Levels of Enrofloxacin, Ciprofloxacin, Sulfaquinoxaline and Oxytetracycline in Broiler Chickens after Drug Administration

The depletion times of enrofloxacin and its metabolite ciprofloxacin as well as sulfaquinoxaline and oxytetracycline were evaluated in broiler chickens that had been subjected to pharmacological treatment. The presence and residue levels of these drugs in muscle tissue were evaluated using an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method that was validated in this work. The results showed the presence of all antimicrobial residues; however, the presence of residues at concentrations higher than the drugs’ maximum residue limit (MRL) of 100 μg kg^-1 was found only during the treatment period for oxytetracycline and until two days after discontinuation of the medication for enrofloxacin, ciprofloxacin and sulfaquinoxaline. It was concluded that the residues of all antimicrobials were rapidly metabolized from the broiler muscles; after four days of withdrawal, the levels were lower than the limit of quantification (LOQ) of the method for the studied analytes.

Magnetic mixed hemimicelles solid-phase extraction coupled with high-performance liquid chromatography for the extraction and rapid determination of six fluoroquinolones in environmental water samples

In this study, a mixed hemimicelle solid-phase extraction method based on Fe3 O4 nanoparticles coated with sodium dodecyl sulfate was applied for the preconcentration and fast isolation of six fluoroquinolones in environmental water samples before high-performance liquid chromatography determination. The main factors affecting the extraction efficiency of the analytes, such as amount of surfactant, amount of Fe3 O4 nanoparticles, extraction time, sample volume, sample pH, ionic strength, and desorption conditions, were investigated and optimized. The method has detection limits from 0.05 to 0.1 ng/mL and good linearity (r ≥ 09948) in the range 0.1-200 ng/mL depending on the fluoroquinolone. The enrichment factor is ∼200. The recoveries (at spiked levels of 1, 5, and 50 ng/mL) are in the range of 79-120%.

Well-defined nanostructured surface-imprinted polymers for highly selective magnetic separation of fluoroquinolones in human urine

The construction of molecularly imprinted polymers on magnetic nanoparticles gives access to smart materials with dual functions of target recognition and magnetic separation. In this study, the superparamagnetic surface-molecularly imprinted nanoparticles were prepared via surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization using ofloxacin (OFX) as template for the separation of fluoroquinolones (FQs). Benefiting from the living/controlled nature of RAFT reaction, distinct core-shell structure was successfully constructed. The highly uniform nanoscale MIP layer was homogeneously grafted on the surface of RAFT agent TTCA modified Fe3O4@SiO2 nanoparticles, which favors the fast mass transfer and rapid binding kinetics. The target binding assays demonstrate the desirable adsorption capacity and imprinting efficiency of Fe3O4@MIP. High selectivity of Fe3O4@MIP toward FQs (ofloxacin, pefloxacin, enrofloxacin, norfloxacin, and gatifloxacin) was exhibited by competitive binding assay. The Fe3O4@MIP nanoparticles were successfully applied for the direct enrichment of five FQs from human urine. The spiked human urine samples were determined and the recoveries ranging from 83.1 to 103.1% were obtained with RSD of 0.8-8.2% (n = 3). This work provides a versatile approach for the fabrication of well-defined MIP on nanomaterials for the analysis of complicated biosystems.

Water-compatible molecularly imprinted microspheres in pipette tip solid-phase extraction for simultaneous determination of five fluoroquinolones in eggs

New water-compatible molecularly imprinted microspheres were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization using 3-(2-carboxyethylsulfanylthiocarbonyl-sulfanyl) propionic acid as a hydrophilic chain-transfer agent, and employed as the sorbent of pipet tip molecularly imprinted solid-phase extraction (PT-MISPE) for rapid extraction and screening of ofloxacin, pefloxacin, norfloxacin, ciprofloxacin, and enrofloxacin in eggs. In comparison to conventional SPE methods, the presented PT-MISPE showed special selectivity, easy operation, and accessible device without expensive SPE apparatus. The presented PT-MISPE method combined advantages of dummy molecularly imprinted polymers and pipet tip solid-phase extraction. The presented method was linear over a calibration range of 25-2500 μg/kg with the limits of detections of 0.53-1.07 μg/kg. Good recoveries (89.1-102.5%) were achieved with relative standard deviations of 2.6-4.8%.

Potential of Phragmites australis for the removal of veterinary pharmaceuticals from aquatic media

The potential of Phragmites australis was evaluated for the removal of three veterinary drugs, enrofloxacin (ENR), ceftiofur (CEF) and tetracycline (TET), from aquatic mediums. Results showed that the plant promoted the removal of 94% and 75% of ENR and TET, respectively, from wastewater. Microbial abundance estimation revealed that microorganisms were not a major participant. Occurrence of drugs adsorption to plant roots was observed in small extension. Therefore, main mechanisms occurring were drug removal by plant uptake and/or degradation. Present results demonstrated the potential of P. australis-planted beds to be used for removal of pharmaceuticals from livestock and slaughterhouse industries wastewater.

The effectiveness of sewage treatment processes to remove faecal pathogens and antibiotic residues

Pathogens and antibiotics enter the aquatic environment via sewage effluents and may pose a health risk to wild life and humans. The aim of this study was to determine the levels of faecal bacteria, and selected antibiotic residues in raw wastewater and treated sewage effluents from three different sewage treatment plants in the Western Cape, South Africa. Sewage treatment plant 1 and 2 use older technologies, while sewage treatment plant 3 has been upgraded and membrane technologies were incorporated in the treatment processes. Coliforms and Escherichia coli (E. coli) were used as bioindicators for faecal bacteria. A chromogenic test was used to screen for coliforms and E. coli. Fluoroquinolones and sulfamethoxazole are commonly used antibiotics and were selected to monitor the efficiency of sewage treatment processes for antibiotic removal. Enzyme Linked Immunosorbent Assays (ELISAs) were used to quantitate antibiotic residues in raw and treated sewage. Raw intake water at all treatment plants contained total coliforms and E. coli. High removal of E. coli by treatment processes was evident for treatment plant 2 and 3 only. Fluoroquinolones and sulfamethoxazole were detected in raw wastewater from all sewage treatment plants. Treatment processes at plant 1 did not reduce the fluoroquinolone concentration in treated sewage effluents. Treatment processes at plant 2 and 3 reduced the fluoroquinolone concentration by 21% and 31%, respectively. Treatment processes at plant 1 did not reduce the sulfamethoxazole concentration in treated sewage effluents. Treatment processes at plant 2 and 3 reduced sulfamethoxazole by 34% and 56%, respectively. This study showed that bacteria and antibiotic residues are still discharged into the environment. Further research needs to be undertaken to improve sewage treatment technologies, thereby producing a better quality treated sewage effluent.

Quantitation of fluoroquinolones in honey using tandem mass spectrometry (LC-MS/MS): nested validation with two mass spectrometers

A number of drugs in the quinolone and fluoroquinolone families, approved for veterinary treatment of food animals by various countries, may be used to treat bee diseases and thereby contaminate honey. An LC-MS/MS method has been developed for the quantification of the quinolones: flumequine, nalidixic acid, oxolinic acid, and pipemidic acid; and the fluoroquinolones ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, norfloxacin, ofloxacin, orbifloxacin, marbofloxacin, sarafloxacin, and sparfloxacin. A method-matched calibration curve is used with several internal standards, i.e., ciprofloxacin-d8, Iomefloxacin, and cinoxacin, to correct for the various types of honey matrices: white, light, medium, and dark colors. Enoxacin is added as an external recovery standard. The LOD values range from 0.05 microg/kg (ofloxacin) to 0.4 microg/kg (flumequine). The compounds are verified by LC-MS/MS retention times and ion ratios. Method uncertainty was determined using two separate analytical systems. The method has successfully measured the presence of norfloxacin in several samples of honey imported into Canada.

Simultaneous determination of 8 fluoroquinolone antibiotics in sewage treatment plants by solid-phase extraction and liquid chromatography with fluorescence detection

Fluoroquinolones (FQs) are among the most important antibiotics used in human and veterinary medicines. A simple and effective analytical method based on reversed-phased liquid chromatography with fluorescence was developed and validated for the simultaneous determination of eight FQs in wastewater at trace level. Aqueous samples were extracted using Anpel(TM) MEP cartridges where they were subsequently eluted by formic acid in methanol. The aqueous extracts were analyzed by gradient elution Liquid Chromatography with Fluorescence Detection (LC-FLD), whose mobile phase was composed of acetonitrile and 10 mM tetrabutyl ammonium bromide (TBAB). The limits of detection (LOD) and the relative standard deviation (RSD) were as low as 0.11-1.06 microg/L and 2-5%, respectively. The presented method was successfully applied to quantify FQs in the influent and effluent of several typical Sewage Treatment Plants (STPs) in Shanghai. For the extraction of 100 mL influent and 500 mL effluent sewage water samples, recoveries obtained were between 79-109% and 80%-105%, respectively. 7 FQs were occurred and identified in the STPs with the concentrations varying from 7 ng/L to 1 microg/L. Norfloxacin, ciprofloxacin and lomefloxacin were the most frequently detected antibiotics occurring in the wastewaters. The analytical procedure developed may be used for more in-depth studies on the occurrences and the fate of these commonly used pharmaceuticals in the sewage treatment plants and in the aquatic environment.

[Simultaneous determination of sulfonamides and fluoroquinolones residues in chicken by high performance liquid chromatography-electrospray tandem mass spectrometry]

A method was developed for the simultaneous determination of 10 residual antibiotics--three sulfonamides (sulfadiazine, sulfamethazine and sulfamethoxydiazine) and seven fluoroquinolones (enoxacin, norfloxacin, enrofloxacin, fleroxacin, levofloxacin, lomefloxacin and ciprofloxacin) in chicken by high performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS2). The sample was extracted with 2% acetic acid-acetonitrile for three times and defatted with n-hexane, then purified by an ENVI-18 solid-phase extraction column. After evaporation, the residue was dissolved in the mobile phase of 1 mL. The HPLC separation was performed with a gradient elution program of acetonitrile and water (containing 0.05% formic acid) as the mobile phase. The identification and quantification were done with mass spectrometry. MS2 fragmentation pathways of the ten antibiotics were also analyzed. Good linearities were observed in the range from 0.02 to 2.0 mg/L with correlation coefficients above 0.998 8. The limits of detection (LOD) were 1.10 -6.85 microg/kg and the limits of quantification (LOQ) were 3.68 -22.85 microg/kg. The average recoveries of 10 antibiotics ranged from 68.9% to 102.6% with relative standard deviations below 8.6% (n = 3). The experimental results show that this method is of high sensitivity, good reproducibility, better determination capacity and shorter analysis time. The method can be used for the multi-residue analysis of sulfonamides and fluoroquinolones in animal foods.

Separation of seven fluoroquinolones by microemulsion electrokinetic chromatography and application to ciprofloxacin, lomefloxacin determination in urine

A simple, reliable microemulsion electrokinetic chromatography (MEEKC) method is developed for the simultaneous separation of seven fluoroquinolones (FQs). The best separation is achieved in a carrier electrolyte containing 1% (v/v) heptane, 100 mmol/L sodium dodecyl sulfate (SDS), 10% (v/v) 1-butanol, and 8 mmol/L phosphate-sodium tetraborate buffer at pH 7.30. The proposed method was directly applied to the determination of ciprofloxacin (CPF) and lomefloxacin (LMF) in urine samples of subjects administered either with CPF or LMF.

New materials in sorptive extraction techniques for polar compounds

This paper provides an overview of the new developments in material and format technology that improve the extraction of polar compounds in several extraction techniques. They mainly include solid-phase extraction, but there are also other sorptive extraction techniques, such as stir bar sorptive extraction and solid-phase microextraction that use either fibers or in-tube devices. We focus on new synthesised materials that are both commercially available and "in-house". Most novel materials that enhance the extraction of polar compounds are hydrophilic and have large specific surface area; however, we also cover other leading technologies, such as sol-gel or monolith. We describe the morphological and chemical properties of these new sorbents so that we can better understand them and relate them to their capability of retaining polar compounds. We discuss the extraction efficiency for polar compounds when these polymers are used as sorptive material and compare them to other materials. We also mention some representative examples of applications.

Effective separation and simultaneous determination of seven fluoroquinolones by capillary electrophoresis with diode-array detector

A simple, rapid and accurate method has been developed for effective separation and simultaneous determination of lomefloxacin, gatifloxacin, enoxacin, ciprofloxacin, ofloxacin, enrofloxacin and pefloxacin residues in porcine tissue by capillary electrophoresis with diode-array detector. The separation conditions were investigated and optimized. The sample was extracted with acetonitrile, and a mixture consisted of 25 mM NaH(2)PO(4), 25 mM Na(2)B(4)O(7) and 25 mM H(3)BO(3) (pH 9.0) was used as a running buffer. A linear relationship between concentration and peak area for each compound was obtained in the concentration range of 0.5-100 mg/L with a correlation coefficient greater than 0.9994. For analysis of porcine tissue, the detection limits of lomefloxacin, gatifloxacin, enoxacin, ciprofloxacin, ofloxacin, enrofloxacin and pefloxacin were 0.013, 0.012, 0.023, 0.040, 0.037, 0.035 and 0.034 mg/kg, respectively. The recoveries are in the range of 72-93%. The intra-day precision is less than 5%, and the inter-day precision is less than 10%. The proposed method has high resolution, speed and the extremely small sample volume required. It can permit to confirm the presence of the studied seven fluoroquinolones in porcine tissue at the required maximum residue limit (MRL) level.

Chiral separation of four fluoroquinolone compounds using capillary electrophoresis with hydroxypropyl-β-cyclodextrin as chiral selector

A capillary zone electrophoresis (CZE) investigation on the enantiomeric separation of lomefloxacin, gatifloxacin, pazufloxacin and ofloxacin was undertaken. Resolution of the enantiomers was achieved using hydroxypropyl-beta-cyclodextrin (HP-beta-CD) as the chiral selector. Parameters influencing separation include cyclodextrin concentration, separational potential, pH and organic additive are discussed. A buffer consisting of 70 mM phosphate and 40 mM HP-beta-CD at pH 3.96 was found to be highly efficient for the separation of lomefloxacin, at pH 3.90 for gatifloxacin, at pH 5.04 for pazufloxacin and at pH 2.16 for ofloxacin. To the best of our knowledge, this is the first report on the enantiomeric resolution of lomefloxacin and gatifloxacin applying CE.

[Separation of sitafloxacin epimers by capillary electrophoresis]

Sitafloxacin epimers were separated by capillary zone electrophoresis using gamma-cyclodextrin (gamma-CD) and D-phenylalanine (D-Phe) as chiral selector. The effects of the concentrations of gamma-CD, D-Phe, Cu2+ and pH of buffer were investigated. An uncoated fused-silica capillary of 50 microm i.d. and 60 cm (effective length 52.5 cm) was used. The capillary temperature was maintained at 25 degrees C. Samples were injected under a pressure of 7 kPa for 5 s and separated at 15 kV. A baseline separation of sitafloxacin epimers was achieved with a background electrolyte of 10 mmol/L KH2PO4-K2HPO4(pH 4.5), 10 mmol/L CuSO4, 20 mmol/L gamma-CD and 10 mmol/L D-Phe. The linear range for sitafloxacin was 32 -400 mg/L (0.996). The relative standard deviations (RSDs) of migration time and peak area were less than 1.9% and 3.8% respectively. This method can be applied in qualitative and quantitative analysis for sitafloxacin epimers.

Determination of gatifloxacin in bulk and tablet preparations by high-performance liquid chromatography

A sensitive, precise, and specific high-performance liquid chromatographic (HPLC) method was developed for the assay of gatifloxacin (GATX) in raw material and tablets. The method validation parameters yielded good results and included the range, linearity, precision, accuracy, specificity, and recovery. It was also found that the excipients in the commercial tablet preparation did not interfere with the assay. The HPLC separation was carried out by reversed-phase chromatography on a C18 absorbosphere column (250 x 4.6 mm id, 5 microm particle size) with a mobile phase composed of acetic acid 5%-acetonitrile-methanol (70 + 15 + 15, v/v/v) pumped isocratically at a flow rate of 1.0 mL/min. The effluent was monitored at 287 nm. The calibration graph for GATX was linear from 4.0 to 14.0 microg/mL. The interday and intraday precisions (relative standard deviation) were less than 1.05%.

Separation and determination of seven fluoroquinolones by pressurized capillary electrochromatography

In this paper, pressurized CEC was used for the separation and determination of seven fluoroquinolones (FQs). The effect of different experimental conditions, such as the concentration and pH of the buffer, the organic modifier concentration, the surfactant and ion-paring agents added to the electrolyte, and applied voltage were studied. All the seven FQs were baseline separated using mobile phase containing 27% v/v ACN, 5 mmol/L Na2HPO4 buffer (pH 4.0 adjusted using citric acid), 11 mmol/L SDS, and 0.01% TEA v/v at detection wavelength of 287 nm and at an applied voltage of -10 kV. The calibration curves were linear (r>0.9991) over a concentration range of 1.0-50.0 mg/L for norfloxacin (NFLX); 2.5-50.0 mg/L for fleroxacin (FLX), ciprofloxacin (CPFX), and lomefloxacin (LMX); and 5.0-50.0 mg/L for enoxacin (ENX), ofloxacin (OFLX), and gatifloxacin (GFLX). The detection limits (S/N = 3) for ENX, OFLX, FLX, NFLX, CPFX, LMX, and GFLX were 0.5, 0.8, 0.4, 0.2, 0.4, 0.5, and 1.0 mg/L, respectively. The method is simple, rapid, and reproducible. It was successfully applied to the analysis of fish muscle samples spiked with FQs. Mean recoveries ranged from 81.6 to 97.6%.

Improved liquid chromatographic determination of nine currently used (fluoro)quinolones with fluorescence and mass spectrometric detection for environmental samples

An HPLC method using C18-modified silica as stationary phase has been developed for environmental trace analysis of nine (fluoro)quinolones. Detection is done by fluorescence measurement or MS using the modes of SIM and selected reaction monitoring (SRM). Best separation is achieved with a gradient consisting of 50 mM formic acid and methanol, which is fully compatible with MS coupling. LOQs (S/N of 10) for fluorescence detection are between 10 and 60 microg/L, depending on the analyte. MS detection (SIM and SRM) yields LOQs that are better by a factor of at least an order of magnitude. Sample preconcentration and sample clean-up is accomplished by SPE (preconcentration factor of 1000), leading to LOQs in the low ng/L range. Recoveries of the preconcentration procedure are better than 80% for all analytes. The suitability for real samples has been demonstrated by analyzing surface waters, municipal waste waters, sewage treatment plant effluents, sewage sludge, and sediment taken from rivers and fish ponds. The method should also be useful for determination of residues of (fluoro)quinolones in food or other matrices. The degradation of the (fluoro)quinolones has been examined over 5 days in order to get information about the decomposition rate and the degradation products eventually occurring in the environment.

Improved capillary electrophoretic separation of nine (fluoro)quinolones with fluorescence detection for biological and environmental samples

A capillary electrophoretic method has been developed for the separation of nine (fluoro)quinolones. Detection is done by fluorescence measurement with broad wavelength band excitation between 240 and 400 nm. Best separation is achieved in a carrier electrolyte containing 50 mM H3PO4 adjusted to pH 7.55-acetonitrile (60:40, v/v). Detection limits are in the low microgl(-1) range. The suitability to real samples has been demonstrated by analyzing blood samples and surface water samples. Sample preconcentration and sample clean-up can easily be done by solid-phase extraction. Different phases based on alkyl- or phenyl-modified silica as well as on polymers have been investigated for this purpose. The method should also be useful for determination of residues of (fluoro)quinolones in food or other matrices.

[Corneal precipitation of fluoroquinolones with magnesium]

Infrared spectrophotometric analysis (FTIR) was performed on a crystalline deposit developed in a corneal ulcer by an old woman who received ciprofloxacine ophthalmic drops. We collected the data of the literature on the subject. After in vitro crystallization experiments, we conclude that ciprofloxacin and norfloxacin corneal precipitates occur at physiological lachrymal pH with magnesium.

Determination of enro?oxacin and its primary metabolite, cipro?oxacin, in pig tissues. Application to residue studies

A simple and sensitive HPLC method has been developed for the simultaneous determination of enrofloxacin (ENR) and ciprofloxacin (CIP) in pig tissue using difloxacin (DIF) as internal standard. Tissue sample preparations were carried out by adding phosphate buffer (pH 7.4, 0.1 m), followed by extraction with trichloromethane. Fluoroquinolones were separated on a reversed-phase column and eluted with aqueous buffer solution-acetonitrile (80:20, v/v). The concentrations of CIP, ENR and DIF eluted from the column, with retention times of 2.20, 2.73 and 4.38 min, respectively, were monitored by fluorescence detection at lambda(ex) 276 and lambda(em) 442 nm. The detection and quantitation limit were 8 and 25 ng/g, respectively, for both compounds. Standard curves were linearly related to concentration in the range 25-400 ng/g. The consequences of the introduction of minor reasonable variations (ruggedness studies) have also been analysed. Finally, the measurement of the tissue levels of ENR and CIP in the pig tissues after oral administration confirmed the utility of the proposed method.

High-Throughput Mass Spectrometer Using Atmospheric Pressure Ionization and a Cylindrical Ion Trap Array

The analytical performance of an atmospheric pressure sampling, multiple-channel, high-throughput mass spectrometer was investigated using samples of a variety of types. The instrument, based on an array of cylindrical ion traps, was built with four independent channels and here is operated using two fully multiplexed channels (sources, ion optics, ion traps, detectors) capable of analyzing different samples simultaneously. Both channels of the instrument were incorporated within the same vacuum system and operated using a common set of control electronics. A multichannel electrospray ionization source was assembled and used to introduce samples including solutions of organic compounds, peptides, and proteins simultaneously into the instrument in a high-throughput fashion. Cross-talk between the channels of the instrument occurred in the detection system and could be minimized to 1-2% using shielding between detector channels. In this initial implementation of the instrumentation, an upper mass/charge limit of approximately 1300 Th was observed (+13 charge state of myoglobin) and unit mass/charge resolution was achieved to approximately 800 Th. The rather limited dynamic range (2-3 orders of magnitude for low-concentration analytes) is due to cross-talk contributions from more concentrated species introduced into a different channel. Analysis of mixtures of alkylamines and peptides is demonstrated, but analysis of mixtures with a wide spread in mass/charge ratios was not possible due to mass discrimination in the ion optics. Further refinement of the vacuum system and ion optics will allow the addition of more channels of parallel mass analysis and facilitate applications in fields such as proteomics and metabolomics.

[Fluorescence spectroscopy determination of lomefloxacin by charge transfer complex formation with chloranilic acid]

Charge-transfer complex was formed between LMX as the donor and Chloranilic Acid (CL) as the acceptor has been studied by fluorimetry. It was shown that the n-pi complex can be formed at ambient temperature, which can emit, which strong fluorescence. Different variables and parameters affecting the reactions were studied and optimized. Based on this, a simple and reliable fluorescence spectroscopy method for the determination of Lomefloxacin (LMX) has been developed. Interference from some co-formulated drugs was also studied. No interference was observed due to additives commonly present in the pharmaceutical preparations. The proposed methods could be applied successfully to the investigated pure compounds and pharmaceutical dosage forms with good accuracy and precision. The linear range is 0.04-0.8 mg x L(-1), the detection limit is 0.04 mg x L(-1), the recoveries of LMX are 97.4%-99.3%, and RSD is 1.3%-2.6%. Finally, the charge-transfer reaction mechanism was discussed. The composition of the change-transfer complex was found to be 1:1 by Bent-French and curved intersection methods. This ratio may be due to the presence of the fluorine atom acting as an electron drawing group in the molecule of lomefloxacin. The benzene ring has lower electron density, but nitrogen atom in 4' of piperazingl has higher electron density and is less sterically hindered. So n-pi charge transfer complexes were formed.

A reverse-phase HPLC assay for the simultaneous determination of enrofloxacin and ciprofloxacin in pig faeces

A reverse-phase HPLC assay is described for the simultaneous assay of enrofloxacin (ENR) and ciprofloxacin (CPX) in pig faeces. Extraction used dichloromethane, 2-propanol and 0.3M ortho-phosphoric acid (1:5:4 v/v/v). Separation was achieved using a Spherisorb S5 C8 column, heated to 50 degrees C and a mobile phase of 0.16% ortho-phosphoric acid (adjusted to pH 3.0 with tetrabutylammonium hydroxide solution) with 20 ml acetonitrile per litre solution. The method used fluorescence detection (Ex 310 nm; Em 445 nm), a flow rate of 1 ml/min and a 20 microl injection volume. Retention times were approximately 6 min for ciprofloxacin and 10 min for enrofloxacin. The linearity range for both compounds was 0-20 mg/kg, lowest limit of quantification 0.3 mg/kg and recoveries were >92%.

Furoquinoline alkaloids from Teclea nobilis

Five new furoquinoline alkaloids, namely tecleabine (1), tecleoxine (2), isotecleoxine (3), methylnkolbisine (4) and chlorodesnkolbisine (5) were isolated from the aerial parts of Teclea nobilis, together with seven known furoquinoline derivatives; one acridone alkaloid, and one known flavanone. The structures of the alkaloids 1-5 were established by 1D and 2D NMR spectral data, including COSY, HMQC and HMBC experiments, as well as HRMS.

Simultaneous measurement of fluoroquinolones in eggs by a combination of supercritical fluid extraction and high pressure liquid chromatography

Simultaneous detection of the fluoroquinolone antibiotics ciprofloxacin, enrofloxacin, ofloxacin, and norfloxacin in eggs by a combination of supercritical fluid extraction (SFE) and high pressure liquid chromatography (HPLC) was studied. Lipid matrices that have been considered to result in poor extraction and isolation of fluoroquinolones in eggs were removed first by SFE with supercritical CO(2) alone, and then the fluoroquinolones were extracted by SFE with supercritical CO(2) containing 20% (v/v) methanol for HPLC analysis. A time-course study of the extraction of lipid matrices of eggs suggested that the SFE method successfully removed the matrices within 20 min. When the fluoroquinolones added to control eggs were extracted by SFE, the extraction efficiency was similar to that by the solvent extraction method, giving the recovery percentages from 83 to 96% in a 40 min-extraction time. The fluoroquinolones extracted from eggs by SFE were analyzed simultaneously by HPLC equipped with a fluorescence detector with detection sensitivity at about 10 ppb for the detection limit. The standard calibration profiles of fluoroquinolones showed linear responses to HPLC, showing more than 0.995 for the mean r(2) value. This is the first report of the simultaneous measurement of fluoroquinolones in eggs by a combination of SFE and HPLC. Using the SFE method allowed us to avoid extensive sample preparation such as solvent extraction and chromatographic cleanup that are basically required in extraction of fluoroquinolones.

High-performance liquid chromatographic separation of fluoroquinolone enantiomers: a review

Fluoroquinolones are antibacterial agents widely used clinically. In recent years, there has been an important development of new derivatives, and more than 7000 analogues have been described today. Different fluoroquinolones (FQ) have one or two chiral centers in their chemical structure and are available as racemates, diastereoisomers, or pure enantiomers. The clinical and pharmaceutical uses of these compounds need effective analytical procedures for quality control and pharmacodynamic and pharmacokinetic studies. This review article focuses on the high-performance liquid chromatographic separation of fluoroquinolone stereoisomers by the use of derivatization methods and ligand exchange (LE) or chiral liquid chromatography.

[Impurity analysis and their structure determination of gatifloxacin]

AIM

To analyse the impurities of gatifloxacin.

METHODS

The impurity of gatifloxacin were analysized and determinated by RP-HPLC/electrospray ionization mass spectrometry with a Zorbax SB-C18(4.6 mm x 150 mm ID, 5 microns). The mobile phase was 3% acetic acid/acetonitrile-3% acetic acid/water (15:85). The two compounds were synthesized: 1-cyclopropyl-6-fluoro-1, 4-dihydro-8-methoxy-7-(1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid (DMP) and 1-cyclopropyl-6-fluoro-1, 4-dihydro-8-hydro-7-(3-methy-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid (DMO). Their liquid chromatogram, UV, MS were compared with those of the impurity of gatifloxacin.

RESULTS

The mass of the impurity was 14 less than that of gatifloxacin. It means the impurity was CH2 less than gatifloxacin. The tR (HPLC), UV and MS of DMP were the same as those of the impurity of gatifloxacin.

CONCLUSION

Based on the tR (HPLC), UV and MS, the impurity of gatifloxacin is confirmed as DMP.