Oxidative transformation of ciprofloxacin by alkaline permanganate – A kinetic and mechanistic study

This spectroscopic study presents the kinetics and degradation pathways of oxidation of ciprofloxacin by permanganate in alkaline medium at constant ionic strength of 0.04 mol⁻³. Orders with respect to substrate, oxidant and alkali concentrations were determined. Effect of ionic strength and solvent polarity of the medium on the rate of the reaction was studied. The oxidation products were identified by LC-ESI-MS technique. Product characterization of ciprofloxacin reaction mixtures indicates the formation of three major products corresponding to m/z 263, 306, and 348 (corresponding to full or partial dealkylation of the piperazine ring). The piperazine moiety of ciprofloxacin is the predominant oxidative site to KMnO₄. Product analyses showed that oxidation by permanganate results in dealkylation at the piperazine moiety of ciprofloxacin, with the quinolone ring essentially intact. The reaction kinetics and product characterization point to a reaction mechanism that likely begins with formation of a complex between ciprofloxacin and the KMnO₄, followed by oxidation at the aromatic N1 atom of piperazine moiety to generate an anilinyl radical intermediate. The radical intermediates subsequently undergo N-dealkylation. Investigations of the reaction at different temperatures allowed the determination of the activation parameters with respect to the slow step of proposed mechanism. The proposed mechanism and the derived rate laws are consistent with the observed kinetics.     

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%.     

Photocatalytic ozonation degradation of ciprofloxacin using ZnO nanoparticles immobilized on the surface of stones

Ciprofloxacin is used in the treatment of bacterial infections. Because ciprofloxacin is not effectively degraded by biological processes, advanced oxidation processes such as photocatalytic ozonation are applied to remove this antibiotic from wastewater. The aim of this study was to investigate photocatalytic ozonation for the removal of ciprofloxacin from aquatic environments and optimization of the effective parameters of the process. For this purpose, ZnO nanoparticles were synthesized using the thermal method and immobilized on the surface of stones. The structural properties of the nanoparticles were determined by XRD, TEM, Photoluminescence (PL) and SEM. Experiments were carried out in a Plexiglas reactor supported with the continuous injection of ozone. The effective parameters for removal efficiency were reaction time, initial concentration of ciprofloxacin, pH, photocatalyst concentration and reaction kinetics. The highest ciprofloxacin removal efficiency occurred at the following optimal conditions: pH of 7, reaction time of 30?min, photocatalyst concentration of 3?g/L and initial ciprofloxacin concentration of 10?mg/L. Removal efficiency of 96% was obtained under these conditions. Linear kinetic models showed that the process followed pseudo-first order and Langmuir-Hinshelwood kinetics. This process had a high removal efficiency and suitable for removal of ciprofloxacin from aquatic environments.GRAPHICAL ABSTRACT     

UV/TiO2 photodegradation of metronidazole,ciprofloxacin and sulfamethoxazole in aqueous solution: An optimization and kinetic study

Emerging pharmaceutical ingredients (APIs) like sulfamethoxazole (SMX), metronidazole (MNZ) and ciprofloxacin (CIP) are biopersistent and toxic to the environment and public health. In this study, UV/TiO₂ photodegradation was applied in the degradation of SMX, MNZ and CIP individually and in a mixture. For a 5 mg/L SMX solution, about 97% of SMX was degraded within 360 min, which was reduced to 80% for 80 mg/L of SMX solution at the same TiO₂ dosage and photodegradation time. The maximum removals of MNZ and CIP as individual components were 100% and 89%, respectively at 600 min of photodegradation reaction time. For binary mixtures, the highest removal (100%) was achieved for MNZ and CIP ([MNZ] = [CIP] = 40 mg/L) mixture at 120 min whereas the degradations were 97% and 96% for SMX and MNZ, and SMX and CIP binary mixtures, respectively, even after 600 min of experimental time at the same concentrations. For tertiary mixture, the maximum degradation 99% was observed for (SMX = CIP] = 20 mg/L and [MNZ] = [40 mg/L) at 600 min. The observed reaction rate was 0.01085 min^?1 when SMX concentration was 5 mg/L, which decreased to 0.00501 min^?1 for SMX concentration of 80 mg/L, indicating decreasing of reaction rate at higher concentration. The results indicate that the UV/TiO₂ process is promising to apply for the treatment of pharmaceutical wastewaters.     

离子对色谱法测定万乳康注射液中淫羊藿苷和盐酸左旋咪唑含量

建立了反相离子对色谱法同时测定万乳康样品中淫羊藿苷和盐酸左旋咪唑的含量。本法使用Shim-pack VP-ODS色谱柱(250×4.6 mm,5μm),该流动相为65%甲醇(V/V),10.0 mmol/L的十二烷基磺酸钠,pH=3.0;等度洗脱样品中的淫羊藿苷和盐酸左旋咪唑。紫外检测波长270 nm。结果表明:淫羊藿苷测定的线性范围为2.73~54.58μg/mL,加标回收率为99.45%~100.69%,理论塔板数达6 641;盐酸左旋咪唑测定的线性范围为26.23~524.54μg/mL,加标回收率为99.58%~100.23%,理论塔板数5 564。该方法可用于淫羊藿提取物和万乳康样品中的淫羊藿苷和盐酸左旋咪唑的测定。     

氯化铯和氯化镧溶剂体系及四类新化合物的合成

研究了四元体系ＣｓＣｌ－ＬａＣｌ３－ＨＣｌ－Ｈ２Ｏ（２５℃、「ＨＣｌ」＝１３％（ｗｔ），２３％（ｗｔ）和ＣｓＣｌ－ＬａＣｌ３－ＨＡｃ－Ｈ２Ｏ（３０℃，「ＨＡｃ」＝４２％（ｗｔ））的平衡态的溶度数据，并给出制了相应的溶度图，共得到了ＣｓＣｌ．ＬａＣｌ３．４Ｈ２Ｏ、２ＣｓＣｌ．ＬａＣｌ３．２Ｈ２Ｏ和３ＣｓＣｌ．ＬａＣｌ３．３Ｈ２Ｏ３种化合物。对得到的新相进行了热分析，Ｘ射线粉末衍射及偏光性质的测定，依     

盐酸环丙沙星含量测定方法的研究

本文介绍了盐酸环丙沙星含量测定的离子选择电极法，紫外分光光度法和格兰线性滴定三种不同方法。用于原料药回收率的测定分别为９９．４％，９９．６７％和９９．５％；用于片剂回收率测定分别为９８．８５％，９８．８４％和９８．７３％。结果基本相同，与非水滴定法相比具有测试方便、快速等优点。     

Hydrothermal syntheses,crystal structures and antibacterial activities of two Cu(II) complexes with quinolones

Hydrothermal reactions of ciprofloxacin with Cu(ClO₄)₂?·?6H₂O, and ofloxacin with Cu(CH₃COO)₂?·?4H₂O, yield two metal complexes: [Cu(H-Cip)₂]?·?(ClO₄)₂?·?6H₂O (1) and [Cu(Ofl)₂?·?H₂O]?·?2H₂O (2), which were characterized by elemental analysis, IR and single crystal diffraction analyses. Compounds 1 and 2 were screened for antibacterial activities against Staphylococcus aureus, Escherichia coli, Candida albicans and pseudomonas aeruginosa.     

间接原子吸收法测定乳酸环丙沙星

研究了在弱酸性介质中，乳酸环丙沙星与雷氏盐定量生成缔合物的反应条件，以及通过原子吸收法测定沉淀中Cr的含量而间接测定乳酸环丙沙星含量的分析方法。线性范围在5－40mg/L，相对标准偏差为2．5％，回收率在98％－101％之间。     

Use of the diphasic dialysis as a new extraction procedure in the determination of enrofloxacin and ciprofloxacin in egg

We have developed a new method for the analysis of the fluoroquinolones enrofloxacin and ciprofloxacin in eggs using a diphasic dialysis procedure as extraction and purification method. High pressure liquid chromatography-mass spectrometry (HPLC-MS) was used for the confirmatory determination of these compounds. The method was found to be linear between 10 and 800 ng g⁻¹ for enrofloxacin, and between 20 and 1600 ng g⁻¹ for ciprofloxacin. The recovery percentages were in the 70-104% range for enrofloxacin, and 55-97% for ciprofloxacin. The assay described was repeatable and reproducible with a limit of quantitation of 2 and 4 ng g⁻¹ for enrofloxacin and ciprofloxacin from egg, respectively.