Validated liquid chromatography–tandem mass spectrometry method for quantification of ticagrelor and its active metabolite in human plasma

A rapid, simple and sensitive LC–MS/MS method was established and validated for simultaneous quantification of ticagrelor and its active metabolite AR‐C124910XX in human plasma. After plasma samples were deproteinized with acetonitrile, the post‐treatment samples were chromatographed on a Dikma C₁₈ column interfaced with a triple quadrupole tandem mass spectrometer. Electrospray negative ionization mode and multiple reaction monitoring were adopted to assay ticagrelor and AR‐C124910XX. Acetonitrile and 5 mΜ ammonium acetate was used as the mobile phase with a gradient elution at a flow rate of 0.5 mL/min. The method was linear in the range of 0.781–800 ng/mL for both ticagrelor and AR‐C124910XX with a correlation coefficient ≥0.994. The intra‐ and inter‐day precisions were within 12.61% in terms of relative standard deviation and the accuracy was within ±7.88% in terms of relative error. The LC–MS/MS method was fully validated for its sensitivity, selectivity, stability, matrix effect and recovery. This convenient and specific LC–MS/MS method was successfully applied to the pharmacokinetic study of ticagrelor and AR‐C124910XX in healthy volunteers after an oral dose of 90 mg ticagrelor.     

Simultaneous quantification of levofloxacin,pefloxacin, ciprofloxacin and moxifloxacin in microvolumes of human plasma using high‐performance liquid chromatography with ultraviolet detection

Levofloxacin, pefloxacin, ciprofloxacin and moxifloxacin are four fluoroquinolones used in the treatment of serious bacterial infections. The antibacterial activity of fluoroquinolones is concentration dependent. Therefore, therapeutic drug monitoring in daily clinical practice is warranted to ensure the therapy's efficacy and prevent bacterial resistance. The purpose of the present study was to develop a method using high‐pressure liquid chromatography with an ultraviolet detector for simultaneous quantification of these four fluoroquinolones in human plasma. A 50 μL aliquot of plasma was precipitated by 200 μL of methanol using gatifloxacin as internal standard. The chromatographic separation was performed on a Kinetex XB‐C₁₈ column using a mobile phase composed of a mixture of orthophosphoric acid 0.4% (v/v), acetonitrile and methanol at a flow rate of 1.2 mL/min. Dual UV wavelength mode was used, with levofloxacin and moxifloxacin monitored at 293 nm, and pefloxacin and ciprofloxacin monitored at 280 nm. The calibration was linear over the ranges of 0.125–25 mg/L for levofloxacin, 0.1–20mg/L for moxifloxacin and 0.05‐10 mg/L for both pefloxacin and ciprofloxacin. Inter‐ and intra‐day trueness and precision were <13% for all the compounds under study. The proposed method was simple, reliable, cost‐effective and suitable for therapeutic drug monitoring or pharmacokinetics studies.     

Simultaneous determination of major components of Huangqi–Honghua extract in rat plasma using LC–MS/MS and application to a pharmacokinetic study

A sensitive and reliable LC–MS/MS method was developed and validated for simultaneous quantification of the major components of Huangqi–Honghua extact in rat plasma, including hydroxysafflor yellow A (HSYA), astragaloside IV (ASIV), calycosin‐7‐O‐β‐d ‐glucoside (CAG), calycosin, calycosin‐3′‐O‐glucuronide (C‐3′‐G) and calycosin‐3′‐O‐sulfate (C‐3′‐S). After extraction by protein precipitation with acetonitrile and methanol from plasma, the analytes were separated on a Hypersil BDS C₁₈ column by gradient elution with acetonitrile and 5 mM ammonium acetate. The detection was carried out on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization source switched between negative and positive modes. HSYA was monitored in negative ionization mode from 0 to 4.9 min, and ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S were determined in positive ionization mode from 4.9 to 10 min. The lower limits of quantification of the analytes were 6.25 ng/mL for HSYA, 0.781 ng/mL for CAG and 1.56 ng/mL for ASIV and calycosin. The intra‐ and inter‐assay precision (RSD) values were within 13.43%, and accuracy (RE) ranged from ?8.75 to 9.92%. The validated method was then applied to the pharmacokinetic study of HSYA, ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S in rat after an oral administration of Huangqi–Honghua extract.     

氯化镉与对甲基苯胺配位反应的热化学研究

用新型的具有恒定温度环境的反应热量计,以一定比例的 HCl（3.0 mol·L-1）与无水乙醇的混合溶液作为量热溶剂,分别测定了反应物[CdCl2·5/2H2O,p-tol]和产物[Cd（p-tol）2Cl,H2O]的溶解焓,设计了一个新的热化学循环,得到了氯化镉与对甲基苯胺配位反应的反应焓△rHm=-7.598kJ·mol1-,并计算出了配合物Cd（p-tol）2Cl2的标准生成焓.推荐其值为:△rHm=（p-tol）2Cl2,s]=-490.773kJ·mol-1     

一个新的凋亡抑制蛋白P49的表达及氨基酸序列分析

从海灰翅夜蛾核型多角体病毒（SpliNPV)中新发现的p49基因可抑制病毒感染引起的草地贪夜蛾细胞Sf9的凋亡，用杆状病毒表达系统Bac to Bac克隆表达并收获P49蛋白，发现所测定的表达蛋白的氨基酸序列与由核苷酸推导的氨基酸序列一致，证明p49基因经克隆转染后得到正确表达，P49蛋白上－^91TVTDG^95－氨基酸序列为Caspase识别结构，比较P35与P49蛋白，两蛋白同源性约为48．8％，且都具Caspase识别和切割的氨基酸序列。     

人工神经网络应用于维生素B族4组分同时测定

应用人工神经网络原理，采用Levenberg-Marquardt BP算法，对于吸收光谱严重重叠的维生素B1，B2，B6和烟酰胺4组分同时进行含量测定。四者的平均回收率分别为100％，98％，96％，100％。该方法用于复合维生素B片剂中B1，B2，B6和烟酰胺的同时测定，获得较满意的结果。实验表明，该方法与现有的算法相比具有训练速度快、预测结果准确度高等特点，有望能成为多组分分析的有效方法之一。     

电子信息工程专业综合课程设计实践教学改革

介绍了北京信息科技大学电子信息工程专业课程设置;指出了各课程之间由于独立授课,知识点相对零散,不容易成体系的问题,提出了开设"综合课程设计"以解决这方面问题;并分析了"综合课程设计"的教学内容以及对学生与指导教师的要求.通过"综合课程设计"的开设,能使教师和学生对本专业的知识体系及前沿研究领域有更深入的了解,更好地适应信息行业的最新发展.     

微量吸附量热法研究氧化物催化剂的酸碱性质

利用微量吸附量热技术定量地表征了Eu₂O₃、CeO₂、MgO、ZnO、Al₂O₃和NiO等氧化物表面酸碱中心的强度和数量,结果表明,样品的NH₃和CO₂起始吸附热与其Sanderson电负性相关.     

刚性微粒填充高聚物的宏观本构关系

用微观力学和统计方法研究了含损伤过程的刚性粒子填充高聚物的非线性本构关系．在材料的变形过程中，粒子与基体间界面的开裂引发微孔洞的成核与长大，这虽然弱化了材料的宏观力学性能，但是带来了宏观本构的非线性效应，这为材料的增韧奠定了基础．该文分析了刚性粒子对材料的强化作用和微孔洞演化对材料的弱化作用，以及这两种竞争机制的耦合效应对宏观本构关系的影响，并从理论上给出了界面强度，粒径分散度，平均粒径等参量对材料宏观力学行为影响的定量分析结果．