氧氟沙星的荧光光谱与质子化作用研究

研究了氧氟沙星(Ofloxacin,OFL)在不同pH条件下的荧光光谱、紫外光谱和质子化作用。在强酸性溶液中,OFL分子可以结合两个质子而以三元酸H₃L2+的形式存在,最大荧光发射波长(λ_max)为505 nm。随着pH值升高,OFL的荧光光谱发生变化,在激发光谱中352 nm 形成一等荧光点,同时在紫外吸收光谱中出现等色点,这一光谱特征表明H₃L2+逐渐失去4位C羰基氧结合的质子。在pH 2.5～4范围内,OFL以H₂L+形式存在,λ_max为499 nm。当pH＞4时,随pH值升高,位于499 nm 的荧光发射峰逐渐蓝移至455 nm,在484 nm形成一等荧光发射点,表明C-3位羧基质子的离解。在pH 7左右,OFL以双极离子HL形式存在,λ_max为455 nm,是最强的荧光型体。当pH＞8时,随pH值升高,λ_max由455 nm红移至约475 nm,同时荧光强度下降,表明HL失去哌嗪环N-4上结合的质子。当pH＞10时,OFL以阴离子L-形式存在, 荧光强度随pH值升高而降低,但λmax基本不变,表明介质环境对OFL的荧光性质有一定影响。     

粉煤灰基氧氟沙星分子印迹聚合物的制备及其应用

以工业废料粉煤灰微球为基质,氧氟沙星 (OFL) 为模板分子,采用表面印迹法制备印迹材料MIP。通过紫外光谱法结合理论分析选择实验条件,并对该印迹材料结构、吸附行为进行研究。结果表明,该印迹材料对氧氟沙星具有良好的特异识别性和优良的亲和性。与以硅胶为载体制备的印迹聚合物相比,该材料吸附容量更高和印迹效果更好。将其作为固相萃取填料对鸡产品进行分离富集,与C18柱相比,分离富集效果更好。结合UPLC,对实际样品中氧氟沙星进行分析,回收率为82.0%-96.7%,相对标准偏差低于5.5%,可用于鸡产品中氧氟沙星分离分析。     

荧光层析法研究由胶束溶液分离出的两种抗菌素

喹诺酮药物是一类重要的化学合成抗菌素 ,其临床应用正在不断扩大[1] 。氧氟沙星 (OFLX)和环丙沙星 (CPLX)结构非常相似。本文采用胶束薄层色谱法分离了两种药物。加入 1%氨水的 0 0 0 15mol·L-1十六烷基三甲基溴化铵 (CTAB)和 1%十二烷基磺酸钠 (SDS)的等体积水溶液作为展开剂 ,聚酰胺薄膜作为固定相。考查了CTAB浓度 ,SDS浓度及氨水对氧氟沙星和环丙沙星Rf 值的影响。在选定条件下 ,Rf 值分别为 0 87和 0 76 ,在激发波长为 2 80nm处对其进行了荧光测定。测定了该方法的稳定性和灵敏度。本文首次使用胶束溶液分离了氧氟沙星和环丙沙星     

Preparation of temperature sensitive molecularly imprinted polymer for solid-phase microextraction coatings on stainless steel fiber to measure ofloxacin

A kind of new temperature sensitive molecularly imprinted polymer (MIP) with ofloxacin (OFL) as template was prepared for the coating of solid phase microextraction (SPME). Dopamine was self-polymerized on stainless steel fiber (SSF) as the SPME support followed by silanization. Then MIP was synthesized as SPME coating on the modified SSF in a capillary, with N-isopropyl acrylamide as temperature sensitive monomer and methacrylic acid as functional monomer. The synthesis could be well repeated with multiple capillaries putting in the same reaction solution. The obtained MIP fiber was evaluated in detail with different techniques and various adsorption experiments. At last the MIP fiber was used to extract the OFL in milk. Satisfied recoveries between 89.7 and 103.4% were obtained with the limit of quantification (LOQ_LC) of 0.04 μg mL⁻¹ by the method of SPME coupled with high performance of liquid chromatography (HPLC).     

镧系离子(Eu3+,Tb3+)氧氟沙星配合物的合成和光谱表征

本文报道了镧系离子Eu3 + ,Tb3 + 同喹诺酮羧酸类衍生物氧氟沙星形成配合物的合成。用元素分析法和ICP确定了配合物的组成为Ln(oflo) 3 Cl3 ·8H2 O。红外光谱表明氧氟沙星配体羧基同中心离子发生螯合 ,并可能与邻位羰基形成六元环稳定结构。荧光光谱表明 ,Eu配合物具有很宽的激发谱带 (2 0 0～ 45 0nm) ,明显区别于其他羧酸类的稀土配合物 ;中心离子Eu3 + 发射谱位于 5 79 0nm(5D0 7F0 ) ,5 92 2nm(5D0 7F1) ,6 12 2nm(5D0 7F2 ) ;而Tb3 + 配合物则同时有配体和中心离子的荧光发射     

Determination of quinolone antibiotics in urine by capillary electrophoresis with chemiluminescence detection

A novel and simple method is presented for the determination of norfloxacin, ciprofloxacin, and ofloxacin by capillary electrophoresis with chemiluminescence detection. This method is based on the enhancing effect of quinolones on the chemiluminescence reaction of the Ce(SO₄)₂–Ru(bpy)₃²⁺–HNO₃ system. Three quinolones were successfully separated and detected under optimum conditions. The obtained detection limits were 2.3×10^–7 mol/L, 5.2×10^–8 mol/L, and 7.8×10^–8 mol/L for ciprofloxacin, norfloxacin, and ofloxacin, respectively. The RSD of migration time and peak area were less than 1.8 and 3.8% (n = 5), respectively. The applicability of the proposed method was illustrated in the determination of ofloxacin in eye drops and of norfloxacin in human urine samples, and the monitoring of pharmacokinetics for norfloxacin.     

Voltammetric Detection of Ofloxacin in Human Urine at a Congo Red Functionalized Water‐Soluble Carbon Nanotube Film Electrode

A simple physical method was developed for the surface modification and the solubilization of MWNTs in water by Congo red. The resulting water‐soluble MWNTs (MWNTs‐CR) can form stable and uniform films on solid supports when dried, which was used to fabricate MWNTs‐CR modified glassy carbon electrodes (MWNTs‐CR/GCE). Voltammetric studies showed that MWNTs‐CR/GCE exhibited a strong enhancement effect on the electrooxidation of ofloxacin. MWNTs‐CR films were also proved to possess overwhelming advantages as electrochemical sensing films over other commonly used MWNTs composite films (e.g., MWNTs‐DHP and MWNTs‐Nafion), reflected by the higher oxidation current, lower background and stronger accumulation capacity towards less soluble species. The sensitive oxidation of ofloxacin at MWNTs‐CR/GCE was used for the determination of ofloxacin. Under optimal conditions, the oxidation current was proportional to ofloxacin concentration in the ranges of 5×10^?8–3.0×10^?5 M. The detection limit of 9×10^?9 M was obtained for 350 s accumulation at open circuit (S/N=3). This method was applied to the determination of ofloxacin in human urine and the result was satisfying.     

Molecular structure and vibrational spectra of γ-oxo [1,1′-biphenyl]-4-butanoic acid (fenbufen) and its interaction with ofloxacin

The Fourier transform Raman and Fourier transform infrared spectra of fenbufen (γ-oxo [1,1′-biphenyl]-4-butanoic acid) were recorded in the solid phase. The gas-phase structure and conformational properties of fenbufen were determined by quantum-chemical calculations (HF and DFT/B3LYP with 6-311++G(d,p) basis set). The harmonic wave numbers were calculated by the density functional theory (DFT) calculations with B3LYP functional and 6-311++G(d,p) basis set, and the scaled values were in good agreement with the majority of the experimental observations. A complete assignment of the fundamentals was proposed based on the total energy distribution (TED) calculation. The possible interaction between fenbufen and ofloxacin which is a synthetic antimicrobial agent was investigated. The changes observed in some bands of mixed drug indicated that there is an interaction between the two drug molecules.     

Simultaneous determination of malondialdehyde and ofloxacin in plasma using an isocratic high-performance liquid chromatography/fluorescence detection system

This study establishes the applicability of using high-performance liquid chromatography (HPLC) with fluorescence detection for the simultaneous determination of malondialdehyde (MDA) and ofloxacin (OFL). The MDA and OFL were separated through a reverse-phase C18 column (250 mm × 4.6 mm) at a flow rate of 1.0 mL min⁻¹ and then detected using a fluorescence detector (excitation: 532 nm; emission: 553 nm). The separation conditions were optimized by varying the concentration and pH of the phosphate buffer and the percentage of organic solvent; the optimal mobile phase was a mixture of 50 mM phosphate buffer (adjusted to pH 5.8 with potassium hydroxide) and methanol (45:55, v/v). The retention times of MDA and OFL were 3.6 and 5.9 min, respectively, with detection limits (at a signal-to-noise ratio of 3) of 0.015 and 4.0 μM, respectively. This method afforded linear responses between the MDA and OFL concentrations and the HPLC peak areas within the ranges 0.15-2.43 μM and 0.06-1.0 mM, respectively. The precisions of the determinations of MDA and OFL, measured in terms of relative standard deviations, were 1.6-5.0% and 1.9-3.6%, respectively, for intra-day assays and 1.0-4.3% and 0.3-1.8%, respectively, for inter-day assays. The average recoveries of MDA and OFL spiked in plasma were 100.4% and 98.8%, respectively. To the best of our knowledge, this paper describes the first practical analytical approach toward simultaneously monitoring the levels of MDA and OFL in plasma. The OFL-induced oxidative stress measured using this method indicated that OFL treatment did not markedly increase the level of MDA.     

Open tubular layer of S‐ofloxacin imprinted polymer fabricated in silica capillary for chiral CEC separation

An open tubular molecule imprinted polymer (OT‐MIP) capillary column has been prepared for chiral separation of ofloxacin enantiomers in CEC. The S‐ofloxacin imprinted OT column was fabricated by thermally initiated non‐covalent polymerization procedure inside a pretreated and silanized fused silica capillary. The template molecule was incorporated with methacrylic acid (MAA), ethylene glycol dimethacrylate (EDMA) and 4‐styrenesulfonic acid (4‐SSA) and dissolved in a porogen mixture of ACN/2‐propanol (9:1). The separation efficiency of the 4‐SSA MIP column was found quite better than that of the MIP column without 4‐SSA. It has been demonstrated that our OT‐MIP column can separate ofloxacin enantiomers with excellent chiral separation efficiency after tuning the various chromatographic conditions. The optimized chromatographic eluent was 85:15, v/v%, ACN/60 mM sodium acetate at pH 7. The separation efficiency and selectivity of chiral separation of this study were far better than those obtained by previous methods for chiral separation of R‐ and S‐ofloxacin.