Spectrofluorimetric determination of trace amount of coenzyme II using ciprofloxacin-terbium complex as a fluorescent probe

A new spectrofluorimetric method was developed for the determination of trace amount of nicotinamide adenine dinucleotide phosphate (NADP). Using terbium ion (Tb³⁺)-ciprofloxacin (CIP) complex as a fluorescent probe, in the buffer solution of pH=9.00, NADP can remarkably enhance the fluorescence intensity of the Tb³⁺-CIP complex at and the enhanced fluorescence intensity of Tb³⁺ ion is in proportion to the concentration of NADP. Optimum conditions for the determination of NADP were also investigated. The dynamic range for the determination of NADP is 4.9×10⁻⁷−3.7×10⁻⁶ mol L⁻¹ with detection limit of 1.3×10⁻⁷ mol L⁻¹. This method is simple, practical and relatively free interference from coexisting substances and can be successfully applied to determination of NADP in synthetic water samples. Moreover, the enhancement mechanisms of the fluorescence intensity in the Tb³⁺-CIP system and the Tb³⁺-CIP-NADP system have been also discussed.     

咖酚伪麻片中盐酸伪麻黄碱的含量

建立高效液相色谱法测定咖酚伪麻片中盐酸伪麻黄碱含量的方法。色谱柱为C18（150mm×4.6mm×5μm）,流动相为0.05mol/L磷酸二氢钠-甲醇（75∶25）,流速为1mL/min,检测波长为210nm。盐酸伪麻黄碱在0.2155—1.0776μg/g范围内线性良好,r=0.9999;盐酸伪麻黄碱的平均收率为100.92%,RSD值为0.41%（n=5）。此法操作简单,准确性好,可用于咖酚伪麻片中盐酸伪麻黄碱的含量测定。     

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.     

GC–MS characterisation and antibacterial activity evaluation of Nigella sativa oil against diverse strains of Salmonella

Salmonella resistance is becoming a worldwide serious health issue in these days; therefore, it is an urgent need to develop some alternative approaches to overcome this problem. Twenty bacterial strains were isolated and purified from different environmental sources and confirmed as Salmonella by morphological and biochemical analyses. Further confirmation was done by 16s rRNA sequencing. Antibiotic susceptibility test was performed by well diffusion assay against different concentrations of Ceftriaxone and Ciprofloxacin. The behaviour of both antibiotics was different against diverse strains of Salmonella. Salmonella strains resistant to both antibiotics were analysed for antibacterial activity of natural extracts of Nigella sativa (black seeds). N. sativa oil was found to be more effective against Salmonella species for which even Ceftriaxone and Ciprofloxacin were ineffective. Gas chromatography and mass spectrometry analysis of N. sativa oil was also accomplished, exhibiting 10 compounds including thymoquinone, p-cymene, cis-carveol, thymol, α-phellandrene, α-pinene, β-pinene, trans-anethole, α-longipinene and longifolene.     

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.     

磷酸基团在环丙沙星光敏损伤DNA中的作用

利用紫外-可见稳态吸收光谱, 稳态荧光发射光谱和激光光解瞬态光谱实验方法研究了磷酸基团在环丙沙星(CPX)光敏损伤DNA中的作用. 紫外-可见和稳态荧光光谱实验证实了磷酸根离子影响环丙沙星的稳态吸收和发射谱, 实验结果表明磷酸根是通过弱相互作用与环丙沙星结合. 我们还利用激光闪光光解实验分别研究了鸟苷(Gua), 脱氧鸟苷(dG)以及脱氧鸟苷酸(dGMP)对环丙沙星三线态(³CPX^*)的影响, 通过对比实验证实了在环丙沙星光敏损伤dGMP中, 由于磷酸基团的存在, 导致了环丙沙星三线态吸收峰的改变, 从而改变了光敏损伤反应的途径. 通过研究发现, 光敏损伤途径的改变是由于dGMP结构上磷酸基团通过氢键与环丙沙星结合所造成的. 最后, 根据实验结果并对比Gua, dG和dGMP的结构, 提出了一个合理的磷酸基团的作用机理.     

盐酸环丙沙星的合成

以３－氯－４－氟苯胺为起始原料，经六步反应合成盐酸环丙沙星，总收率达４２．３％，高于现有文献报道值。经元素分析，红外光谱和核磁共振谱确认了产物的结构。     

二维层状NiO/g-C3N4复合材料在无铁光电类芬顿体系中有效去除环丙沙星的研究

环丙沙星(CIP)的过量使用已经对生态环境造成了很大的威胁。本文设计了一种新型无铁的光电类芬顿体系用于降解水中的CIP。采用溶剂热法合成了NiO/g-C₃N₄复合材料。通过XRD分析,确定了不同催化剂的晶相和化学组成; 红外光谱进一步证实了NiO/g-C₃N₄复合材料的分子结构,结果表明,成功地合成了NiO/g-C₃N₄复合材料。利用SEM观察了材料的形貌,结果表明性能最佳的NiO/g-C₃N₄-60%为二维花状结构。TEM进一步证明NiO/g-C₃N₄-60%具有片层状结构。由于层状结构,NiO/g-C₃N₄-60%具有较大的比表面积和丰富的活性位点,有利于电子的传输。XPS分析表明Ni²⁺和Ni³⁺共存于NiO/g-C₃N₄-60%复合材料中并且NiO/g-C₃N₄-60%具有低配位氧缺陷。EPR谱也证实了氧空位的存在,氧空位不仅促进了H₂O₂的活化,而且有利于金属离子形成稳定的混合价态。UV-Vis-DRS、PL和电化学测试表明NiO/g-C₃N₄-60%具有最强的光吸收能力、最低的电荷转移电阻和最快的电荷分离效率,有利于活性物质的生成和CIP的快速降解。因此,花状NiO/g-C₃N₄-60%在光电类芬顿体系中表现出光电协同作用,不仅可以通过Ni³⁺/Ni²⁺之间的转化将电芬顿过程中产生的H₂O₂有效分解为·OH,同时也能够产生光生电子和空穴,促进光照下·OH、·O₂^-和h⁺的生成,从而提高环丙沙星的降解效率。以催化性能最佳的NiO/g-C₃N₄-60%为催化剂时,在90 min内CIP的降解率达到将近100%,120 min时矿化效率达到82.0%,与传统芬顿体系(最佳pH值为2.8–3.5)相比,新型光电类芬顿体系具有较宽的pH范围,当pH值为6时,降解率仍可达78.8%。NiO/g-C₃N₄-60%在光电类芬顿体系中也表现出良好的结构稳定性,连续5次循环后,降解效率仍保持在96.3%。根据HPLC-MS的结果,提出了CIP降解的两种可能途径。本研究为废水中抗生素的快速降解提供了理论依据。