A rapid and simple high-performance liquid chromatography method for the determination of human plasma levofloxacin concentration and its application to bioequivalence studies

A high-performance liquid chromatography method with fluorescence detection (HPLC-FLD) for the determination of levofloxacin in human plasma is described. Neutralized with phosphate buffer (pH 7.0), the sample (0.1 mL) was extracted with dichlormethane (1 mL). After voltex-mixing and centrifuged at 3000g for 6 min at 4 degrees C, the upper aqueous layer was aspirated using a micro vacuum pump and the organic layer was directly transferred to a clean test tube without pipetting. The organic solvent was evaporated and the residues were reconstituted with the mobile phase. Levofloxacin and terazosin (internal standard, IS) were chromatographically separated on a C(18) column with a mobile phase containing phosphate buffer (pH 3.0, 10 mm), acetonitrile and triethylamine (76:24:0.076, v/v/v) at a flow rate of 1 mL/min. The analytes were detected using fluorescence detection at an excitation and emission wavelength of 295 and 440 nm, respectively. The linear range of the calibration curves was 0.0521-5.213 microg/mL for levofloxacin with a lower limit of quantitation (0.0521 microg/mL). The retention times of levofloxacin and terazosin were 2.5 and 3.1 min, respectively. Within- and between-run precision was less than 12 and 11%, respectively. Accuracy ranged from -6.3 to 4.5%. The recovery ranged from 86 to 89% at the concentrations of 0.0521, 0.5213 and 5.213 microg/mL. The present HPLC-FLD method is sensitive, efficient and reliable. The method described herein has been successfully used for the pharmacokinetic and bioequivalence studies of a levofloxacin formulation product after oral administration to healthy Chinese volunteers.     

A POSITRON CT CAMERA SYSTEM USIUG MULTIWIRE PROPORTIONAL CHAMBERS AS DETECTORS

A positron CT camera system using multiwire proportional chambers as detectors is reported.This system is composed of two high density MWPC γ-ray detectors,an electronic readout system and a computer for data processing.The tomography of three dimensions is obtained.The imaging matrix 64×64×16.     

强激光引起等离子体参量加热的粒子模拟研究

我们利用一维半粒子云网格法作数值模拟、研究了频率略高于等离子体频率(ω₀=1.1ω_v)的强激光电场引起的参量加热。结果表明,离子声衰变不稳定性和振荡双流不稳定性同时被激发,非线性饱和呈现出较为细致的结构,等离子体被强烈加热,饱和后Langmuir湍流谱遵从一个典型的幂规律。     

基于香豆素Schiff碱的Zn2+、Co2+和Ni2+配合物的合成、晶体结构及光谱性质

合成了3个香豆素Schiff碱单核Zn²⁺、Co²⁺和双核Ni²⁺的配合物，[Zn（L¹）₂]（1）（HL¹=6-（（4-二乙胺基-2-羟基-亚苄基）-氨基）-苯并吡喃-2-酮），[Co（L²）₂]（2）（HL²=6-（（4-甲氧基-2-羟基-亚苄基）-氨基）-苯并吡喃-2-酮），[Ni₂（L³）₂（CH₃OH）₄）]（3）（H₂L³=4-羟基-3-（（4-甲氧基-2-羟基-亚苄基）-氨基）-苯并吡喃-2-酮）。利用元素分析、红外光谱、紫外可见光谱、荧光光谱及X射线单晶衍射分析等手段对其进行了表征。X射线单晶衍射分析结果表明：配合物1和配合物2均为单核结构，由1个金属离子和2个配体单元组成；配合物3具有双核结构，由2个金属离子、2个配体单元及4个配位的甲醇分子组成。配合物1、2和3分别是单斜晶系、三斜晶系和三斜晶系，所属的空间群分别为C2/c、P1和P2₁/n；中心金属Zn²⁺和Co²⁺离子的空间构型为四配位的四面体，Ni²⁺离子的空间构型为六配位的扭曲的八面体。此外，通过对配体HL¹和HL²的紫外可见光谱性质研究发现，在DMF/H₂O（4：1，V/V）溶液中，自由配体HL¹和HL²分别可以选择性识别Hg²⁺和Zn²⁺，通过计算得到其检测限分别为7.45和6.10 μmol·L^-1。荧光性质研究发现在DMF/H₂O（4：1，V/V）溶液中自由配体HL²可以检测Zn²⁺，检测限为2.91 μmol·L^-1。     

白藜芦醇作辣根过氧化物酶底物的布氏杆菌抗体酶联免疫传感器研究

一种纯天然产物白藜芦醇用作辣根过氧化物酶(HRP)底物。对其化学性质的研究证实,白藜芦醇在空气中较稳定,对HRP、H2O2的电化学响应性能优于传统HRP底物,对人体无毒害。白藜芦醇在HRP催化下可被H2O2氧化成醌,产物醌在电极上于-376 mV处可被还原,其电流的大小与HRP的浓试在一定浓度范围内呈线性相关。将兔布氏杆菌抗原包埋在石墨-石蜡基质中制备了测定兔布氏杆菌抗体的电化学酶联免疫传感器,该传感器测定兔布氏杆菌抗体的线性范围为3×10-4~1.65×10-2g/L;检出限为1×10-4g/L;RSD为4.6%。本方法制备免疫传感器的电化学性能稳定,抗原活性保持良好。     

分光光度法测定蒙药黑冰片中微量钼

苯基荧光酮(苯芴酮)-CTMAB分光光度法测定黑冰片中钼的含量.实验结果表明,钼在0-15.029μg/mL范围内有良好的线性关系,其回归方程为:A=0.981714C585-0.157942(r=0.976).回收率为99.8%.RSD为0.948%.     

Low-threshold-intensity 3.8-W continuous-wave Ti:Sapphire oscillator directly pumped with green diodes

Applied Physics B - Two-wavelength and two-color laser-induced incandescence (2λ–2C-LII) was used to study the absorption properties of three types of cold soot of different maturity...     

二氢卟吩e6赖氨酸酰胺稳定性及电子光谱

采用密度泛函理论在B3LYP/6-31G^*水平上对二氢卟吩e6(简称e6)及设计的6个e6赖氨酸酰胺进行几何优化, 对优化构型用B3LYP/6-31G^**法进行单点计算, 并用含时密度泛函理论LSDA/6-31G^**方法计算电子吸收光谱. 结果表明, 赖氨酸的ε-NH₂与e6连接的酰胺更稳定, 其中, 15位的乙酰胺Y_ε最稳定. 形成赖氨酸酰胺改善了e6 的水溶性, 有利于药物吸收. 各e6 赖氨酸酰胺的前线轨道集中于二氢卟吩环, 由于连接酰胺基侧链的二氢卟吩环平面性有所下降, 前线轨道能隙略为升高, 最大电子吸收波长相对于e6 蓝移16-39 nm, 但仍处于光动力治疗窗口“600-900 nm”. 酰胺链的构象对吸收波长影响较大, Y_ε三个较稳定构象中, 酰胺链垂直于二氢卟吩环的Y_ε1和Y_ε2的二氢卟吩环平面性较好, 最大吸收波长比酰胺链与二氢卟吩环近似平面的Y_ε红移53、50nm, 三者平均值较e6红移18 nm.     

退火对电子束热蒸发193nm Al2O3/MgF2反射膜性能的影响

设计并镀制了193nm Al₂O₃/MgF₂反射膜，对它们在空气中分别进行了250—400℃的高温退火，测量了样品的透射率光谱曲线和绝对反射率光谱曲线.发现样品在高反射区的总的光学损耗随退火温度的升高而下降，而后趋于饱和.采用总积分散射的方法对样品在不同退火温度下的散射损耗进行了分析，发现随着退火温度的升高散射损耗有所增加.因此，总的光学损耗的下降是由于吸收损耗而不是散射损耗起主导作用.对Al₂O₃材料的单层膜进行了同等条件的退火处理，由它们光学性能的变化推导出它们的折射率和消光系数的变化，从而解释了相应的多层膜光学性能变化的原因.反射膜的反射率在优化联系、镀膜工艺与退火工艺的基础上达98％以上. 关键词： 193nm 反射膜 退火 光学损耗 吸收     

Optochemical sensor for an ornidazole assay using 1-amino-4-allyloxyanthraquinone as a fluorescent indicator.

To improve the stability of optochemical sensors (optodes), the fluorescence indicator 1-amino-4-allyloxyanthraquinone (AAA), which was synthesized by reacting allyl bromide with 1-amino-4-hydroxyanthraquinone, was covalently immobilized on surface-modified glass slides. The resulting sensor was used to determine the content of ornidazole based on fluorescence quenching. It showed a linear response toward ornidazole in the concentration range of 9.0 x 10(-6) to 1.0 x 10(-3) mol L(-1) with a detection limit of 8 x 10(-6) mol L(-1) at pH 7.5. This AAA-immobilized sensor has a rapid response, high stability and good selectivity to ornidazole.