一些酸性药物在正相硅胶/反相洗脱色谱中保留机理研究

用液相色谱法中“溶质计量置换保留模型”(SDM-R)的两个线性公式,分析了正相硅胶/反相洗脱色谱体系中酸性药物分子与固定相和流动相分子间的相互作用机理,研究了流动相pH值、离子强度、温度和强溶剂浓度改变对溶质保留的影响。从而阐明了酸性药物的保留机理为一种以反相色谱为主的与正相色谱共存的混合保留机理。此方法可以作为药物制剂和中药材中酸性药物成分的分离测定方法。     

用胶束色谱法研究非甾体抗炎药的疏水性

本文使用胶束色谱法研究了某些非甾体抗炎药的疏水性。检查了胶束色谱保留值与文献logPow的相关性。观察了表面活性剂SDS浓度的影响。对于胶束洗脱剂,logK'与logPow的相关好于k与logPow.与logk'w((甲醇—水为洗脱剂得到的外推容量因子)相比,logk'与logPow的相关性较好。logKMw(胶束—水结合常数)或logK'o(胶束浓度为零时的保留因子)与logPow也存在着线性相关。结果表明在药物定量构效关系的研究中使用胶束色谱进行药物疏水性的定量测定是很有希望的。     

生物分配胶束色谱的药物定量结构保留关系

目的建立药物在生物分配胶束色谱的定量结构保留关系,解析药物在生物分配胶束色谱的保留机理,用于预测新化合物的保留行为,以指导新化合物的设计。方法采用逐步回归与偏最小二乘回归等化学计量学方法,对110个药物的生物分配胶束色谱保留因子与影响药物吸收的基本物理化学参数等进行线性回归,建立药物保留行为的预测模型。结果建立了基于影响药物吸收的物理化学参数的药物生物分配胶束色谱定量结构保留关系,采用测试集进行外部验证显示模型具有良好的预测能力(R2>0.82)。药物的疏水性[正辛醇/水分配系数(P)的对数值的计算值,cal-culated logP,ClogP]、电荷(δ)、分子量(molecular weight,MW)、总表面积(total surface area,TSA)等对其在生物分配胶束色谱的色谱保留作用显著。结论药物在生物分配胶束色谱的定量结构保留关系建立有助于解析药物的保留行为,指导新化合物的设计,提高新药研发的成功率。     

胶束薄层色谱分离甘草活性成分的影响因素及优化方法

目的:为甘草的胶束薄层色谱指纹图谱寻找最优胶束流动相。方法:首先采用单因子法,寻找影响甘草胶束薄层色谱的影响因素,在此基础上,采用控制加权可变步长单纯形优化法进行甘草胶束薄层色谱指纹图谱的流动相优化。结果:对甘草的胶束薄层色谱分离条件(表面活性剂的种类和含量、醇和酸改性剂的影响等)进行了实验,表明纯胶束薄层色谱的柱效较低,加入醇和酸类改性剂后柱效有明显提高。通过对改性胶束的进一步优化(控制加权可变步长单纯形优化法),得到优化的甘草改性胶束展开剂组成为:0.23 mol.L-1的SDS+16%(v/v)正丁醇+11%(v/v)甲酸。本研究对胶束薄层色谱的一些分离机理亦进行了探讨。结论:胶束薄层色谱的表面活性剂和各添加剂间存在交互作用,需采用合适的优化方法,才能达到分离中药材复杂活性成分群的目的。     

胶束色谱分析黄连及含黄连中成药中小檗碱型生物碱的研究

本文报道用胶束色谱法分离测定黄连(黄柏)及含黄连(黄柏)中成药中黄连碱、药根碱、巴马亭和小槃碱。考察了固定相、胶束浓度、有机改性剂浓度及pH对组分保留行为的影响。实验结果表明;影响该色谱分离的主要因素为固定相极性和胶束浓度。同时在肢束流动相中加入甲醇改性剂,可在室温下显著地提高柱效。用键合苯基固定相,以3.5%十二烷基硫酸钠/0.1 N酒石酸—甲醇(30:70)胶束溶液作流动相,测定了十几种黄连(黄柏)及含黄连(黄柏)的中成药。     

罗红霉素分散片中辅料峰的定性研究

目的考察高效液相色谱中溶质的保留行为,以更好地对溶质进行定性。方法采用不同仪器、不同色谱柱、不同配比流动相、不同柱温及不同流速测定罗红霉素分散片中辅料峰糖精钠的保留行为。结果流速对辅料峰糖精钠的保留行为有一定影响,其他各因素影响不大;各因素对罗红霉素的保留行为影响较大。结论罗红霉素分散片中辅料糖精钠在色谱柱上基本不保留,在一定的流速范围内可以用保留时间直接对糖精钠定性。     

提高高效液相色谱法定性准确性的方法探讨

目的：考察影响高效液相色谱中溶质相对保留时间的因素，并尝试更好的保留时间偏差校正方式。方法：以C18柱为例，运用甲醇一水体系，以苯／萘、甲苯／萘的相对保留时间及相对容量因子为评价指标，考察反相液相色谱系统中可能影响溶质保留行为的因素，包括色谱柱填料、填装工艺、批号、柱效、仪器、流动相比例、流速等。并以乙酰螺旋霉索的分析为例，比较相对保留时间法和相对容量因子法的校正效果。结果：对溶质的相对保留时间影响较大的是色谱柱填料、流动相比例和仪器，丽填装工艺、批号、柱效、流速等因素则影响不大。与相对保留时间法比较，相对容量因子法在校正溶质保留行为的偏差方面，效果更好。在实际样品分析时，同一类色谱柱表现出的选择性基本一致。结论：采取以下方法可以提高高效液相色谱的定性准确性：（1）对色谱柱分类，并选择同一类色谱柱进行实验；（2）用相对容量因子代替相对保留时间校正溶质的保留行为：（3）严格控制流动相的比列．     

注射用头孢哌酮钠舒巴坦钠中头孢哌酮降解物的定性研究

目的：考察高效液相色谱中溶质的保留行为,以更好地对溶质进行定性。方法：采用不同仪器、不同色谱柱、不同配比流动相及不同柱温测定注射用头孢哌酮钠舒巴坦钠中头孢哌酮降解物的保留行为,并比较了用相对容量因子法（α法）和相对保留时间法（RRT法）的校正结果。结果：头孢哌酮降解物的保留行为受各因素影响较大。结论：校正结果表明α法与RRT法相比,能更好地校正溶质的保留行为。     

生物分配胶束色谱法预测中药制剂消炎利胆片膜通透性的研究

目的:基于生物分配胶束色谱法进行复杂中药制剂消炎利胆片的分离和膜通透性预测。方法:考察了生物分配胶束色谱的保留因子与药物膜通透性的相关性,以非离子型表面活性剂Brij 35作为流动相,模拟生物体内环境,得到各受试药物的保留因子Log k,与膜通透性参数(口服吸收率、Log Papp、Log BB)数据进行相关分析得出定量保留-膜通透性(QRPR)模型。结果:预测了消炎利胆片10个主要保留成分的透膜吸收情况。结论:生物分配胶束色谱可以用于中药复杂成分的分离,以及预测药物主成分的透膜吸收活性。     

同系物保留指数作为脂肪酸气相色谱定性参数的优越性考察

本文根据五因素系统分组方差分析的实验结果,考察了所提出的同系物保留指数相对于常用的气相色谱定性参数相对保留值、Kovats保留指数的优越性,得到以下结论:同系物保留指数的固定液配比和柱温因素的相对标准差(变异系数)远比相对保留值和Kovats保留指数的对应值小。因而同系物保留指数最精密。由于同系物保留指数更准确地显示了化学物质的色谱行为,故能比Kovats保留指数更可靠地用于鉴定,并将获得更广泛的应用。Kovats保留指数可看成是同系物保留指数用于烷烃的特例。     

Optimization of selectivity in micellar chromatographic procedures for the determination of drugs in urine by direct injection

Selectivity was optimized for the determination of drugs in urine by direct injection micellar chromatography through changes in specific mobile phase parameters. The r?le of mobile phase pH and the type of surfactant used for mobile phase preparation was investigated. The retention of the urine matrix was found to be minimal between pH 5.5 and 7.5. The non-ionic surfactant, polyoxyethylene 23 lauryl ether (Brij 35), was found to be the surfactant of choice for the separation of drugs from urine. Favourable retention of both the urine background and the analyte was achieved with this surfactant. Micellar mobile phases of optimal composition were used to develop chromatographic procedures for the determination of furosemide, hydrochlorothiazide and propranolol in urine. Good accuracy (98-102% of drug recovered), precision (1-4% RSD) and linearity were obtained for all methods. Limits of detection for all drugs were adequate.     

Direct injection of untreated serum using nonionic and ionic micellar liquid chromatography for determination of drugs

The chromatographic behaviour of nonionic micelles used as the mobile phase in liquid chromatography is similar to that of anionic and cationic micellar mobile phases, with reversal of retention order as the micelle concentration is varied. This behaviour follows the prediction of the model developed for anionic surfactants. Nonionic micelle chromatographic interactions are simplified by reducing the extent of electrostatic interactions with the solute and, as a result, their retention dependencies more closely follow the mathematical predictions. Drugs in blood serum samples are quantitatively determined by direct injection of the serum onto the chromatographic column, with no column clogging or pressure build-up. The results are similar to those found with anionic micellar mobile phases, but are in contrast to the protein precipitation observed with cationic micelles. Solute—micelle equilibrium constants and the critical micelle concentration of Brij-35, determined chromatographically, are reported. The potential usefulness of nonionic micelles for the determination of theophylline, paracetamol, phenobarbital, carbamazepine, quinine, quinidine, morphine, codeine and cocaine is demonstrated.     

Thermodynamic evaluation of activated charcoal as a poison antidote by high-performance liquid chromatography. I: Derivation and validation of an equation for Gibbs free energy of liquid-solid adsorption

An in vitro method utilizing high-performance liquid chromatography (HPLC) was developed in order to investigate the adsorptive process between activated charcoal and various drugs and toxic chemicals by measuring their Gibbs free energy of adsorption from various acetonitrile:water mobile phases. This report details the derivation and validation of the equation for calculating the Gibbs free energy of liquid-solid adsorption via HPLC. The derived equation incorporates the following experimental parameters: specific surface area of the adsorbent, specific retention volume of the solute, molar volume of the mobile phase, and surface concentration of the solute in a predefined standard state. This equation was validated by means of a closed thermodynamic cycle composed of three segments. Each segment represents a different physical process: gas-solid adsorption of methyl iodide on activated charcoal, gas-liquid solution of methyl iodide in n-hexadecane, and liquid-solid adsorption of methyl iodide on activated charcoal from n-hexadecane. The Gibbs free energy for each of these thermodynamic processes was determined by the appropriate chromatographic technique. Since the cycle did not balance because it did not account for the interaction of n-hexadecane and activated charcoal, it was altered to include a gas-liquid-solid chromatographic technique. When the Gibbs free energies of solution and gas-solid adsorption determined by this chromatographic technique were incorporated into the cycle, the resulting imbalance was only 0.213 kJ/mol (1.1%), thereby validating the derived equation.     

Chromatographic behavior of zwitterionic enalapril-exploring the conditions for lipophilicity assessment

The chromatographic behavior of enalapril was investigated under different stationary and mobile phase conditions in an effort to unravel interferences in the underlying retention mechanism, which would affect its relation to octanol-water partitioning. Extrapolated retention factors, logk(w), were used as relevant chromatographic indices. The retention/pH profile was established and the peak split phenomenon, associated with cis/trans interconversion, was also monitored as a function of pH. The pH at maximum retention and minimum peak split occurrence was chosen for further investigation, so that the presence of zwitterionic structure was guaranteed and any effect of cis/trans interconversion could be ignored. Retention of zwitterionic enalapril was found to be very sensitive to mobile phase conditions in regard to organic modifier as well to the aqueous component. The use of morpholine-propanesulfonic acid (MOPS) as buffer and the presence of n-octanol as mobile phase additive proved critical factors for maximum suppression of secondary interactions. Nevertheless, the corresponding extrapolated retention factor was considerably larger than octanol-water logD value at the isoelectric point. However, logk(w) could be successfully converted to logD by means of a calibration equation established for ionized acidic compounds.     

Thermodynamic evaluation of activated charcoal as a poison antidote by high-performance liquid chromatography. II: In vitro method for the evaluation of activated charcoal as a poison antidote

A previous report detailed the derivation and validation of an equation for calculating the Gibbs free energy of liquid-solid adsorption via high-performance liquid chromatography (HPLC). This study utilizes an improved form of that equation in conjunction with an in vitro model of solute adsorption to give an ordered listing of the antidotal activity of activated charcoal towards different drugs and other chemicals. The in vitro model consists of an activated charcoal column with a nominal particle diameter of 15 micron and a surface area of 447 x 10(4) cm2/g, together with a series of acetonitrile:water mobile phases at pH 3. A simple and efficient procedure was developed for ranking the solutes. First, each compound was run in an acetonitrile(ACN):water mobile phase chosen to give a convenient retention time and ideal chromatographic response. The capacity factor for this mobile phase was extrapolated to give a predicted capacity factor for a 35:65 (v/v) ACN:water mobile phase using an empirical equation developed from the exhaustive chromatography of four standard compounds (phenobarbital, strychnine, cyclohexanone, methyl ethyl ketone) in a variety of ACN:water mobile phases. In addition to the standards, 12 other compounds (glutethimide, chlordiazepoxide, quinine, brucine, d-propoxyphene, pentobarbital, methyprylon, methadone, meperidine, codeine, antipyrine, morphine) were evaluated. Based on these data, the Gibbs free energies of liquid-solid adsorption for these compounds were calculated and used to evaluate activated charcoal as a poison antidote for them. The results indicate that a rapid and accurate estimation of the utility of activated charcoal as an antidote for drugs and toxic substances can be obtained from a single chromatographic run of the test compound.     

对-羟基苯甲酸印迹整体柱识别机制研究

目的：采用原位热引发聚合法制备分子印迹整体柱,在高效液相色谱上考察印迹整体柱在不同色谱条件下分子印迹整体柱选择性的变化。利用计量置换模型对实验数据进行模拟,研究决定分子印迹整体柱选择性识别能力的主要因素。方法：以甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,甲苯和异辛烷为致孔剂,偶氮二异丁腈为引发剂,选择原位热引发聚合法,制备以对-羟基苯甲酸为模板的分子印迹整体柱。在高效液相色谱上考察印迹整体柱对模板分子的特异选择性;系统考察了向流动相中依次加入水、甲醇、乙醇和异丙醇4种强氢键竞争溶剂后对-羟基苯甲酸、邻-羟基苯甲酸和对-硝基苯甲酸容量因子的变化,利用计量置换模型对实验数据进行模拟。结果：制得的分子印迹整体柱对模板分子具有特异选择性;在流动相中加入强氢键竞争溶剂后,各种样品的容量因子以及印迹整体柱的选择性均降低;计量置换模型模拟结果显示lnk值用来表示分子印迹聚合物的分离效率,n值用来表示当溶质和印迹聚合物间的相互作用是氢键时,被分离样品和印迹聚合物之间相互作用的空间效应。结论：当强氢键竞争性溶剂加入流动相中时印迹聚合物孔穴结构的匹配性决定了印迹体系的特异识别能力。