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Spectrochimica Acta. Part A, Molecular... Feb 2020The self-association of fluoroquinolones (FQ) in water would play a relevant role in their translocations across lipid membranes. Triplet excited states of these drugs...
The self-association of fluoroquinolones (FQ) in water would play a relevant role in their translocations across lipid membranes. Triplet excited states of these drugs have been shown as reporters of FQ self-association using laser flash photolysis technique. A study using low-temperature phosphorescence technique was performed with quinolone derivatives such as enoxacin (ENX), norfloxacin (NFX), pefloxacin (PFX), ciprofloxacin (CPX, ofloxacin (OFX), nalidixic acid (NLA), pipemidic acid (PPA) and piromidic acid (PRA) to explore emission changes associated with self-associations and to shed some light on the triplet excited state energy (E) discrepancies described in the literature for most of these drugs. The emissions obtained at 77 K in buffered aqueous medium revealed that the amphoteric nature of the quinolones CPX, NFX, PFX, ENX, OFX and PPA must generate their self-associations because a redshift of their phosphorescence maxima is produced by FQ concentrations increases. Hence, this effect was not observed for NLA and PRA or when all quinolones were analysed using ethanol or ethylene glycol aqueous mixtures as glassed solvents. Interestingly, the presence of these organic mixtures produced a blue-shift in the phosphorescence emission maximum of each FQ. Additionally, laser flash photolysis experiments with PRA and the amphoteric quinolone PPA, compounds with the same skeleton but different peripheral substituent, confirm the expected correlations between the amphoteric nature of compounds and their self-associations in aqueous media because the excimer generation was only detected for PPA. Now, the discrepancies described in the literature for the E of FQs can be understood considering that changes of medium polarity or proticity as well as the temperature can considerably modify their E values. Thereby, low-temperature phosphorescence technique, is an effective way to detect molecular self-associations and surrounding changes in quinolones that opens the possibility to evaluate these effects in other drug families.
Topics: Buffers; Dimerization; Fluoroquinolones; Luminescent Measurements; Models, Molecular; Photolysis; Water
PubMed: 31670049
DOI: 10.1016/j.saa.2019.117569 -
Food Additives & Contaminants. Part A,... Jun 2018Seventeen quinolone antibiotics were determined in cows' milk. A method of high sensitivity, selectivity and accuracy was developed. Accuracy (trueness and precision),...
Seventeen quinolone antibiotics were determined in cows' milk. A method of high sensitivity, selectivity and accuracy was developed. Accuracy (trueness and precision), linearity, sensitivity, selectivity, decision limit and detection capability were established following the recommendations of the Commission Decision 2002/657/EC and the Food and Drug Administration (FDA) guideline. The use of polar stir-bar sorptive extraction (SBSE) prior to UHPLC-MS/MS analysis is proposed. The variables that affect SBSE were optimised using multivariate optimisation strategies. The ionic strength, the extraction time and the sample volume were studied. pH and stir-bar coating (polydimethylsiloxane, PDMS, and polyethyleneglycol modified silicone, PEG) were studied. PEG showed the best extraction yield at pH 6. For validation, a matrix-matched calibration and a recovery assay were carried out. Limits of quantification from 0.5 μg kg for nalidixic acid, flumequine and piromidic acid, to 4.0 μg kg for sarafloxacin were calculated. The precision (%, RSD) was lower than 15% for all antibiotics. Recoveries in fortified samples were between 88 and 114%.
Topics: Animals; Cattle; Chromatography, High Pressure Liquid; Drug Residues; Food Contamination; Milk; Quinolones; Solid Phase Extraction; Tandem Mass Spectrometry
PubMed: 29368583
DOI: 10.1080/19440049.2018.1430382 -
The Science of the Total Environment Jan 2013Laboratory-scale batch experiments were developed to investigate the main removal routes for 6 commonly found quinolones (ciprofloxacin, moxifloxacin, norfloxacin,...
Laboratory-scale batch experiments were developed to investigate the main removal routes for 6 commonly found quinolones (ciprofloxacin, moxifloxacin, norfloxacin, ofloxacin, pipemidic acid, and piromidic acid), in wastewaters from a wastewater treatment plant, at μg L(-1) levels in an aerobic sludge system from a membrane bioreactor (MBR) pilot plant. It was demonstrated that sorption and biotransformation were the main removal routes for the target antibiotics over other possible pathways, as volatilization or hydrolysis, under the experimental conditions. Mass balances indicated that sorption on sludge played a dominant role in the elimination of antibiotics from waters. The sorption coefficient K(d) depended strongly on temperature and on the quinolone type and were higher at lower temperatures and for piperazinylic quinolones. K(d) values were between 516 and 3746 L kg(-1) in the temperature range of 9-38°C. Higher mixed liquor suspended solids (MLSS) increased quinolone removal efficiency mainly by sorption. Quinolone biodegradation constituted a secondary pathway, and could be described by first-order kinetics with degradation-rate constants ranging from 8.0 × 10(-4)h(-1) to 1.4 × 10(-2)h(-1) within the same temperature range and MLSS from 7000 to 15,000 mg L(-1). Biodegradation depended on the MLSS and temperature, but also on the initial chemical oxygen demand (COD). Higher biodegradation rates were observed at higher MLSS and temperature, as well as at low initial COD. Ciprofloxacin and moxifloxacin registered the highest biodegradation percentages (52.8% and 47.2%, respectively, at 38°C and 15,000 mg L(-1) MLSS), which is evidence that, despite the known persistence of this group of antibiotics and removal from waters mainly by sorption, it was possible to improve their removal by biodegradation, with an appropriate selection of conditions and control of process variables, as a preliminary step towards the elimination of these antibiotics from the environment. Further research is needed on the possibilities of removing sorbed antibiotics from sludge.
Topics: Adsorption; Aerobiosis; Anti-Bacterial Agents; Biodegradation, Environmental; Biomass; Bioreactors; Filtration; Kinetics; Molecular Structure; Pilot Projects; Quinolones; Sewage; Water Pollutants, Chemical; Water Purification
PubMed: 23178836
DOI: 10.1016/j.scitotenv.2012.10.026 -
Rapid Communications in Mass... Dec 2012Veterinary drug residue analysis of meat and seafood products is an important part of national regulatory agency food safety programs to ensure that consumers are not...
RATIONALE
Veterinary drug residue analysis of meat and seafood products is an important part of national regulatory agency food safety programs to ensure that consumers are not exposed to potentially dangerous substances. Complex tissue matrices often require lengthy extraction and analysis procedures to identify improper animal drug treatment. Direct and rapid analysis mass spectrometry techniques have the potential to increase regulatory sample analysis speed by eliminating liquid chromatographic separation.
METHODS
Flumequine, oxolinic acid, and nalidixic acid were extracted from catfish, shrimp, and salmon using acidified acetonitrile. Extracts were concentrated, dried onto metal sample wells, then rapidly desorbed (6 s) with an infrared diode laser for analysis by laser diode thermal desorption atmospheric pressure chemical ionization with tandem mass spectrometry (LDTD-MS/MS). Analysis was conducted in selected reaction monitoring mode using piromidic acid as internal standard.
RESULTS
Six-point calibration curves for each compound in extracted matrix were linear with r(2) correlation greater than 0.99. The method was validated by analyzing 23 negative samples and 116 fortified samples at concentrations of 10, 20, 50, 100, and 600 ng/g. Average recoveries of fortified samples were greater than 77% with method detection levels ranging from 2 to 7 /g. Three product ion transitions were acquired per analyte to identify each residue.
CONCLUSIONS
A rapid method for quinolone analysis in fish muscle was developed using LDTD-MS/MS. The total analysis time was less than 30 s per sample; quinolone residues were detected below 10 ng/g and in most cases residue identity was confirmed. This represents the first application of LDTD to tissue extract analysis. Published 2012. This article is a US Government work and is in the public domain in the USA.
Topics: Animals; Anti-Bacterial Agents; Aquaculture; Calibration; Catfishes; Drug Residues; Limit of Detection; Mass Spectrometry; Quinolones; Reproducibility of Results; Seafood; Veterinary Drugs
PubMed: 23136016
DOI: 10.1002/rcm.6414 -
Journal of Chromatography. A Dec 2008A sensitive liquid chromatography-electrospray tandem mass spectrometry method, combined with solid-phase extraction and a weak cation exchange cartridge cleanup, was...
A sensitive liquid chromatography-electrospray tandem mass spectrometry method, combined with solid-phase extraction and a weak cation exchange cartridge cleanup, was established for twenty quinolone and fluoroquinolone antibiotics (pipemidic acid, flerofloxacin, ofloxacin, pefloxacin, enoxacin, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, lomefloxacin, difloxacin, sarafloxacin, gatifloxacin, sparfloxacin, moxifloxacin, cinoxacin, oxolinic acid, nalidixic acid, flumequine, and piromidic acid) in influent, effluent, and river waters. For the various water matrices considered, the overall recoveries were from 64% to 127% except for piromidic acid (27-33%), and no obvious matrix effect was observed. The method detection limits for the twenty target antibiotics in the influent, effluent, and surface water samples were 1.6-50 ng/L, 0.6-50 ng/L, and 0.8-50 ng/L, respectively. This method was applied to analyze residual quinolone and fluoroquinolone antibiotics in wastewater and surface water samples from Beijing, China. Eight antibiotics (12 (pipemidic acid)-1208 ng/L (ofloxacin)) were detected in wastewater, and seven (1.3 (lomefloxacin)-535 ng/L (ofloxacin)) were detected in surface water samples. Gatifloxacin, a 4th generation fluoroquinolone antibiotic, was detected for the first time in influent (111 ng/L), effluent (56 ng/L), and river water (16-42 ng/L).
Topics: Anti-Bacterial Agents; China; Chromatography, Liquid; Fluoroquinolones; Quinolones; Reproducibility of Results; Sensitivity and Specificity; Solid Phase Extraction; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry; Water Pollutants, Chemical
PubMed: 19007934
DOI: 10.1016/j.chroma.2008.10.090 -
Talanta May 2000This paper describes a newly developed liquid chromatography-electrospray-mass spectrometry (HPLC-ES-MS) method for the determination of 13 antibacterial reagents...
This paper describes a newly developed liquid chromatography-electrospray-mass spectrometry (HPLC-ES-MS) method for the determination of 13 antibacterial reagents (olaquindox, trimethoprim, clopidol, ormethoprim, morantel, carbadox, thiamphenicol, pyrimethamine, furazolidone, oxolinic acid, difurazon, nalidixic acid, piromidic acid). The optimization for the detection of these compounds by HPLC-ES-MS was investigated. A C(18) column with gradient elution was utilized for the separation of thirteen antibacterial chemicals. Collision induced dissociation (CID) was used to induce fragmentation of analyte molecules and enhance the specificity of the method. Selective ion monitoring (SIM) was employed for quantitative determination. The detection limit of this method proved to be much better than previously reported ones. Satisfactory linearity, 0.5-10 ppm, of each compound was obtained. A solvent extraction method to extract analyte compound from pork was developed. The application of this newly developed method was demonstrated by analyzing antibacterial reagent added pork samples.
PubMed: 18967971
DOI: 10.1016/s0039-9140(00)00321-0 -
Journal of Separation Science Jun 2007A simple chromatographic method is described for assaying 15 quinolones and fluoroquinolones (pipemidic acid, marbofloxacin, enoxacin, ofloxacin, norfloxacin,... (Comparative Study)
Comparative Study
A simple chromatographic method is described for assaying 15 quinolones and fluoroquinolones (pipemidic acid, marbofloxacin, enoxacin, ofloxacin, norfloxacin, ciprofloxacin, danofloxacin, lomefloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, nalidixic acid, flumequine and piromidic acid), in urine and pharmaceutical samples. The determination was achieved by LC using an RP C18 analytical column. A mobile phase composed of mixtures of methanol-ACN-10 mM citrate buffer at pH 3.5 and 10 mM citrate buffer at pH 4.5, delivered under an optimum gradient program, at a flow rate of 1.5 mL/min, allows to accomplish the chromatographic separation in 26 min. For detection, diode-array UV-Vis at 280 nm and fluorescence detection set at excitation wavelength/emission wavelength: 280/450, 280/ 495, 280/405 and 320/360 nm were used. Detection and quantification limits were between 0.3-18 and 0.8-61 ng/mL, respectively. The method was validated in terms of interday (n = 6) and intraday (n = 6) precision and accuracy. The procedure was successfully applied to the analysis of human and veterinary pharmaceuticals. Also, ofloxacin was determined in human urine samples belonging to a patient undergoing treatment with this active principle, among others.
Topics: Animals; Chromatography, High Pressure Liquid; Humans; Ofloxacin; Pharmaceutical Preparations; Quinolones
PubMed: 17623463
DOI: 10.1002/jssc.200600536 -
Journal of AOAC International 2007A multiresidue method was developed to measure low levels of 8 fluoroquinolones (norfloxacin, ofloxacin, danofloxacin, ciprofloxacin, desethylene ciprofloxacin,...
A multiresidue method was developed to measure low levels of 8 fluoroquinolones (norfloxacin, ofloxacin, danofloxacin, ciprofloxacin, desethylene ciprofloxacin, enrofloxacin, sarafloxacin, and difloxacin) and 4 quinolones (oxolinic acid, flumequine, nalidixic acid, and piromidic acid). Method detection limits range from 0.1 ng/g for quinolones to 0.4 ng/g for fluoroquinolones. Average recoveries range from 57 to 96%, depending on analyte and commodity; relative standard deviations are all less than 18%. The drugs are extracted from tissues using a mixture of ethanol and 1% acetic acid, diluted in aqueous HCI, and defatted by extraction with hexane. The compounds are further isolated using cation-exchange solid-phase extraction and measured using liquid chromatography with electrospray tandem mass spectrometry detection. The method has been evaluated and applied to the analysis of salmon, trout, and shrimp. Detectable residues were observed in 10 out of 73 samples, at concentrations ranging from 0.28 to 16 ng/g.
Topics: Acetic Acid; Animals; Anti-Bacterial Agents; Chemistry Techniques, Analytical; Crustacea; Drug Residues; Ethanol; Fishes; Fluoroquinolones; Food Analysis; Food Contamination; Models, Chemical; Quinolones; Spectrometry, Mass, Electrospray Ionization; Trout
PubMed: 17474531
DOI: No ID Found -
Applied and Environmental Microbiology Sep 1997The direct viable count method first described by Kogure et al. (Can. J. Microbiol. 25:415-420, 1979) was improved by using an antibiotic cocktail instead of nalidixic...
The direct viable count method first described by Kogure et al. (Can. J. Microbiol. 25:415-420, 1979) was improved by using an antibiotic cocktail instead of nalidixic acid alone. We screened 100 marine isolates from two coastal areas for their sensitivities to five replication-inhibiting antibiotics, including four quinolones (nalidixic, piromidic, and pipemidic acids and ciprofloxacin) and one (beta)-lactam (cephalexin). It was shown that growth inhibition of all isolates cannot be readily achieved by using a single antibiotic. Inhibition was much more efficient when all the antibiotics were combined, making it possible to use this method with natural communities. In combination, the concentration of each antibiotic could be lowered and the incubation time could be increased without any growth. Under such conditions, it was shown that the fraction of substrate-responsive cells within natural marine communities is much greater (1 to 2 orders of magnitude) than those reported by traditional procedures. Furthermore, the new procedure made substrate-responsive cells more clearly distinguishable. These improvements resulted in an increased incubation time and were related to metabolic expression of slow-growing cells and/or to the recovery of starved cells. The increased fraction of viable cells within marine communities has ecological implications on the metabolic role of nonculturable cells.
PubMed: 16535694
DOI: 10.1128/aem.63.9.3643-3647.1997 -
FEMS Microbiology Ecology Feb 2006Inferences about which microorganisms degrade polycyclic aromatic hydrocarbons in contaminated soils have largely been obtained using culture-based techniques, despite...
Inferences about which microorganisms degrade polycyclic aromatic hydrocarbons in contaminated soils have largely been obtained using culture-based techniques, despite the low percentage of microorganisms in soil that are believed to be culturable. We used a substrate-responsive direct viable count method to identify and quantify potential polycyclic aromatic hydrocarbon-degrading bacteria in a soil containing petroleum wastes. Bacteria were extracted and their response to substrates determined in the presence of DNA gyrase inhibitors, which cause viable and active cells to elongate. When yeast extract, a widely used carbon source, was added as a growth substrate, together with nalidixic acid, piromidic acid and ciprofloxacin, a significant increase in elongated cells to 47%, 37% and 22%, respectively, was observed within 24 h. With pyrene as the main substrate, 10 mg L(-1) of nalidixic acid or piromidic acid caused 18-22% and 8-12%, respectively, of the cells to elongate within 24 h; whereas the effect of 0.5 mg L(-1) ciprofloxacin was not significant until 53 h later. Enlarged cells were identified and enumerated by fluorescent in situ hybridization, using Alpha-, Beta- and Gammaproteobacteria, and domain Bacteria-specific probes. The Bacteria-specific probe detected 35-71% of the total microorganisms detected by the DNA-binding dye 4,6-diamidino-2-phenylindole. Initially, 44%, 13% and 5% of the total bacteria in the soil extract were Alpha-, Beta- and Gammaproteobacteria, respectively. Without pyrene or a gyrase inhibitor, these subgroups decreased to 30% of the total population but were predominant with piromidic acid or unchanged with ciprofloxacin when pyrene was the main substrate. The proportion of elongated Alpha- and Betaproteobacteria (potential pyrene degraders) increased significantly (P<0.05). This approach links phylogenetic information with physiological function in situ without the conventional cultivation of bacteria and can be used to probe and enumerate degradative groups at even a finer level of discrimination.
Topics: Anti-Bacterial Agents; Bacteria; Biodegradation, Environmental; Ciprofloxacin; Colony Count, Microbial; Culture Media; DNA, Bacterial; In Situ Hybridization, Fluorescence; Indoles; Nalidixic Acid; Piromidic Acid; Pyrenes; Soil Microbiology; Staining and Labeling
PubMed: 16420636
DOI: 10.1111/j.1574-6941.2005.00035.x