反相液相制备色谱法结合超临界流体制备色谱法分离纯化海风藤中的化合物

建立了基于反相液相制备色谱和超临界流体制备色谱的组合方法,用于分离纯化醇提水沉后石油醚层中的海风藤。首先以甲醇作为改性剂,采用醇提水沉法去除海风藤甲醇提取物中的叶绿素,加入硅藻土后用石油醚回流富集目标成分。选用反相C18制备色谱柱将其分为18个组分,然后将组分在SFC模式下进行制备。选用酰胺色谱柱,以甲醇为改性剂,在柱温30℃、背压15.0 MPa的条件下进行分离。基于反相色谱和超临界流体色谱不同的分离选择性,最后分离得到6个高纯度化合物。该法展示了反相制备色谱和超临界流体制备色谱在海风藤分离纯化方面的优势,特别是超临界流体色谱在天然产物的分析和制备方面的巨大潜力。     

黄芪中黄酮类化合物的超临界流体色谱分离方法研究

考察了超临界流体色谱（SFC）中的色谱柱、改性剂、添加剂、流速、柱温和背压等因素对9种黄酮类成分（包括芒柄花素、异鼠李素、毛蕊异黄酮、山奈酚、槲皮素、紫云英苷、芒柄花苷、异槲皮苷、毛蕊异黄酮葡萄糖苷）分离的影响,与高效液相色谱法（HPLC）进行了比较,并建立了黄芪饮片中5种主要黄酮类化合物的SFC分析方法。采用Agilent ZORBAX RX－SIL色谱柱（4.6 mm × 150 mm,5 μm）进行分离,CO2－0.1%磷酸甲醇溶液为流动相梯度洗脱,流速为3 mL/min;柱温为35 ℃;背压为10 MPa,9种黄酮类化合物可在10 min内实现基线分离。5种黄酮类化合物在一定质量浓度范围内均具有良好的线性关系（r2 ≥ 0.963 2）,检出限为10.69 ~ 16.21 μg/mL,日内相对标准偏差（RSD）为1.3% ~ 2.0%;日间RSD为1.6% ~ 2.2%。5种黄酮类化合物在48 h内具有良好的稳定性,重复性为3.6% ~ 6.0%,回收率为91.8% ~ 112%。与HPLC法相比,9种化合物的保留时间顺序基本相反,SFC法更快速、经济环保,且其保留及选择性受色谱柱、改性剂和添加剂的影响较大,添加剂对色谱峰形影响明显。     

Separation of Phenylalanine Methylester 5'-Phosphoamidates of d4T Diastereoisomers by Supercritical Fluid Chromatography

采用超临界CO2流体色谱技术,分析d4T-5'-N-磷酰化苯丙氨酸甲酯手性磷的非对映异构体.色谱柱为Hpersil ODS2 (250 mm× 4.6 mm,5 μm),流动相为夹带改性剂甲醇、乙醇和异丙醇的超临界CO2流体.以容量因子、选择性和分离度为指标,考察改性剂、背压和柱温对分离的影响.在甲醇、乙醇和异丙醇3种改性剂中,甲醇为最好的改性剂,其中在7％甲醇改性剂下,该化合物的分离度可达到3.35.在7％甲醇改性剂条件下,考察了压力( 10～20 MPa)和温度(303.15～318.15 K)的影响.在优化的分离条件(改性剂为7％甲醇,流速为2 mL/min,柱温为308.15 K,背压为15 M Pa)下,d4T-5'-N-磷酰化苯丙氨酸甲酯的两种非对映异构体完全达到基线分离,分离时间约15 min.     

超临界流体色谱法分析非对映异构体d4T-5’-N-磷酰化苯丙氨酸甲酯

采用超临界CO2流体色谱技术,分析d4T-5’-N-磷酰化苯丙氨酸甲酯手性磷的非对映异构体。色谱柱为Hpersil ODS2(250 mm×4.6 mm,5μm),流动相为夹带改性剂甲醇、乙醇和异丙醇的超临界CO2流体。以容量因子、选择性和分离度为指标,考察改性剂、背压和柱温对分离的影响。在甲醇、乙醇和异丙醇3种改性剂中,甲醇为最好的改性剂,其中在7%甲醇改性剂下,该化合物的分离度可达到3.35。在7%甲醇改性剂条件下,考察了压力(10～20 MPa)和温度(303.15～318.15 K)的影响。在优化的分离条件(改性剂为7%甲醇,流速为2 mL/min,柱温为308.15 K,背压为15 M Pa)下,d4T-5’-N-磷酰化苯丙氨酸甲酯的两种非对映异构体完全达到基线分离,分离时间约15 min。     

10°锥角台锥型制备液相色谱柱的放大研究

将10°锥角台锥型液相色谱柱放大至150mm长、入口直径54mm、出口直径27mm,容积为200mL,填料为粒径40～75μm、孔径11nm的C18球形硅胶。流动相在锥型柱内呈现塞子状流形。系统地评价了该柱的分离性能,结果表明：在最佳流速为6mL/min时,以萘峰计,锥型柱的折合理论塔板高度为2.11,柱效下降10%时的样品质量和体积载样量分别为2.1mg和1.7mL,与同长度同体积圆柱型柱相比,柱效提高了20%,质量载样量提高了16%以上,体积载样量提高了19%以上。当进样质量由2.4mg增加到12mg时,对羟基苯甲酸乙酯峰与对羟基苯甲酸丁酯峰的分离度（Rs2）由2.14降到1.71,对羟基苯甲酸丁酯峰与萘峰的分离度（Rs3）由2.91降到2.52;当进样体积由3mL增加到19mL,Rs2由2.23降到1.28,Rs3由2.95降到2.30,但此时的色谱峰峰形仍然高度对称,没有拖尾,有利于从基质中制备分离微量组分。实验结果表明锥型液相色谱柱将具有广泛的应用前景。     

超临界流体萃取-高效液相色谱离线联用分析灵芝中三萜类化合物

在系统考察压力、温度和时间对萃取率影响的基础上,利用超临界流体萃取技术提取了灵芝子实体中的三萜类化合物。其最佳萃取条件为:压力15 MPa,温度35℃,动态萃取时间120 m in,CO2流量1 mL/m in,背压阀温度50℃。此外,还建立了高效液相色谱梯度洗脱分离三萜类化合物的方法。通过比较超临界流体提取物和甲醇提取物的色谱图,发现两者具有相似的峰形,说明超临界流体能够达到与甲醇相近的萃取效果,可以取代甲醇作为新一代的绿色萃取溶剂。     

真空液相色谱柱及其应用

混合物的分离是分析测试中的常用技术 ,柱层析是常用的分离方法之一。而传统的色谱柱由于对样品的受纳容量较小和分离速度较慢 ,无法满足某些研究的需要。本法采用并改进了一种分离快速、使用方便、易于制作的ＶＬＣ柱 ,为含磷化合物的复杂反应产物的研究提供了有效工具。ＶＬＣ柱全称为ＶａｃｕｕｍＬｉｑｕｉｄＣｈｒｏｍａｔｏ ｇｒａｐｈｙ ,即真空液相色谱。这是一种制备色谱 ,其流体由于柱下端产生负压而流出。该柱的使用最早于1977年由Ｃｏｌｌ报道[1,2 ] 。Ｃｏｌｌ及其合作者采用这种柱子顺利地进行了一些天然产物的分离 ,但关于柱…     

填充柱超临界流体色谱系统中的溶剂效应

 考察了填充柱超临界流体色谱法 (SFC)中的样品溶剂及连续进样等因素对化合物保留行为变化的影响规律。以超临界 CO2 或含低体积分数甲醇的 CO2 为流动相时 ,氨基柱上组分的保留时间随着样品溶剂的极性增大而增大 ,而溶剂对 C1 8柱上组分的保留时间影响不大 ;在 C1 8柱上 ,溶剂对连续进样的后续效应不强 ;而在氨基柱上 ,甲醇溶液的后续效应比丙酮、氯仿溶液的后续效应强。当甲醇的体积分数大于 1 .0 %时 ,溶剂的效应明显减弱。这种变化规律对填充柱 SFC的合理进样并获得重现性良好的色谱数据具有实际意义。     

饲料中D-泛酸钙的超临界流体色谱测定

采用超临界流体色谱(SFC)测定了饲料中D-泛酸钙的含量.在二氧化碳流动相中添加14.85%甲醇改性剂及0.15%三氟乙酸添加剂,流速2 mL/min,在Kromasil ODS柱上分离,检测波长为210 nm.结果表明D-泛酸钙能在3 min内完成分离,在1.0 ～25.0 mg/L范围内,样品的质量浓度与色谱峰面积呈良好的线性关系(r=0.999 5).方法的精密度良好,相对标准偏差在2.3%以内,回收率为89% ～98%.方法操作简单,结果准确,适合普及应用.     

吸附剂性能和操作参数对液相色谱流出峰不对称性的影响

色谱流出峰的拖尾现象普遍存在于制备和大型色谱分离过程中,它直接影响分离的产率和回收率．本文提出采用色谱流出峰形的不对称偏差度来表征色谱流出峰的拖尾程度;并基于液相制备色谱分离过程FAD－SMT模型及吸附速率理论,通过计算机模拟,定量分析了吸附剂性能和操作参数对色谱流出峰形不对称性的影响。结果表明：不仅是吸附剂的热力学和动力学性能（包括吸附相平衡关系、液固两相间的传质阻力）;而且柱的设计和吸附剂的装填状况（包括轴向扩散系数）,以及色谱分离的操作条件（进料时间、浓度和流速等）都直接影响色谱流出峰形的不对称性。随着吸附相平衡等温线的非线性程度增大,或者总传质系数的减小,色谱流出峰形的不对称偏差度明显增大;吸附剂吸附容量的减小也将引起色谱流出峰形的不对称偏差度的增加;色谱流出峰形的不对称偏差度与进科体积、浓度和流体线速,以及轴向扩散系数的增大成正比。     

Two-dimensional supercritical fluid chromatography/mass spectrometry for the enantiomeric analysis and purification of pharmaceutical samples

A new analytical two-dimensional supercritical fluid chromatography/mass spectrometry system (2D SFC/SFC/MS) has been designed and implemented to enhance the efficiency and quality of analytical support in drug discovery. The system consists of a Berger analytical SFC pump and a modifier pump, a Waters ZQ 2000 mass spectrometer, a set of switching valves, and a custom software program. The system integrates achiral and chiral separations into a single run to perform enantiomeric analysis and separation of a racemic compound from a complex mixture without prior clean up. The achiral chromatography in the first dimension separates the racemate from all other impurities, such as un-reacted starting materials and by-products. Mass-triggered fractionation is used to selectively fractionate the targeted racemic compound based on its molecular weight. The purified racemate from the achiral chromatography in the first dimension is then transferred to the chiral column in the second dimension to conduct the enantiomeric separation and analysis. A control software program, we coined SFC2D, was developed and integrated with MassLynx to retrieve acquisition status, current sample information, and real time mass spectrometric data as they are acquired. The SFC2D program also monitors the target ion signal to carry out mass-triggered fractionation by switching the valve to fractionate the desired peak. The 2D SFC/SFC/MS system uses one CO(2) pump and one modifier pump for both first and second dimension chromatographic separations using either gradient or isocratic elution. Similarly, a preparative 2D SFC/SFC/MS system has been constructed by modifying an existing Waters preparative LC/MS system. All components except the back pressure regulator are from the original LC/MS system. Applications of the 2D SFC/SFC/MS methods to the separation and the analysis of racemic pharmaceutical samples in complex mixtures demonstrated that an achiral separation (in first dimension) and a chiral separation (in second dimension) can be successfully combined into a single, streamlined process both in analytical and preparative scale.     

离线二维反相液相色谱/超临界流体色谱在瓜蒌子分离中的应用

发展了离线二维反相液相色谱/超临界流体色谱(2D RPLC/SFC)分离瓜蒌子的方法。实验在第一维采用反相色谱,按色谱峰收集从瓜蒌子样品中制备得到的12个组分(F_1~F_(12)),并将得到的组分在第二维使用SFC分离。这些组分在RPLC和SFC的分离对比说明,该二维方法具有良好的分离正交性,可至少检测到150个色谱峰,对于解决结构相似物质的分离、微量成分的富集表现出了明显的优势。SFC方法采用了乙醇-正己烷(3∶7,v/v)的混合溶剂作为改性剂,既提供了适当的洗脱能力,也保证了在上样量增加时满足样品溶解的要求。此二维分离体系可放大到制备水平用于化合物的制备,为瓜蒌子化学成分的纯化制备提供技术支持,为其物质基础研究提供参考。     

超临界流体色谱与高效液相色谱分离手性化合物的比较

超临界流体色谱(SFC)分离具有速度快、分离效率高、溶剂消耗少等优点,近年来在手性化合物的分离分析中得到诸多应用。本文对比研究了涂覆型多糖手性色谱柱在SFC和高效液相色谱(HPLC)上拆分24种手性化合物的差异。通过比较这些化合物在色谱柱上的保留时间和选择因子等发现多数化合物在SFC上的分离效率要高于其在HPLC上的分离效率,但HPLC对轴手性化合物的分离效率要优于SFC。SFC和HPLC的分离表现出一定的互补性,随着苯环侧链烷基的碳数增加,化合物在SFC上的保留逐渐增强,而在HPLC的保留却逐渐减弱。叶菌唑在使用SFC和HPLC分析时出现了洗脱顺序反转的现象。这些结果为SFC手性拆分提供了参考。     

Separation of Chlorophylls and Their Degradation Products using Packed Column Supercritical Fluid Chromatography (SFC)

Complex mixtures of chlorophyll degradation products may arise during processing and storage of vegetable oil and green plant materials like broccoli and spinach. Determination of these compounds is important in the area of food chemistry. Therefore a method using packed column supercritical fluid chromatography (SFC) has been developed. The method comprises chromatography using a simple gradient of methanol in carbon dioxide at constant column back pressure of 30 MPa and a column temperature of 40°C. Effects of pressure and mobile phase composition showed the importance of applying a modifier gradient for optimal separation of the chlorophyll products. The method permits separation of 15 chlorophyll derivatives including chlorophyll a and b, pheophytins, and pyropheophytins on a C₁₈ column in about 20 minutes. Identifications of the individual peaks were based on reference compounds, the retention order of the compounds, and their absorption spectra.     

Supercritical fluid chromatographic solvatochromic modifier polarity studies

To understand the chromatographic process as a whole, whether it be for gas chromatography (GC), liquid chromatography (LC), or supercritical fluid chromatography (SFC), one needs to know the chemical and physical nature of the mobile and stationary phases and also the interactions that take place between analytes (solutes) and the two phases. An approach towards Investigating the ways that stationary and mobile phases contribute to chromatographic retention Involves exploring the effects of solvent polarity on the strength of the mobile phase. In SFC this could involve determining the polarity of several different modifier/carbon dioxide mobile phases. In this paper, the use of a solvatochromic indicator to learn more about the effects of SFC modifier/mobile phase polarity will be investigated and discussed using several different modifiers and a diolmodified silica column.     

Chromatographic resolution of closely related species: Drug metabolites and analogs

In this study, we investigate the separation of a variety of mixtures of drugs, metabolites, and related analogs including representatives of the carbamazepine, methylated xanthine, steroid hormone, nicotine, and morphine families using several automated chromatographic method development screening systems including ultra high performance liquid chromatography, core–shell HPLC, achiral supercritical fluid chromatography (SFC), and chiral SFC. Of the 138 column and mobile phase combinations examined for each mixture, a few chromatographic conditions afford the best overall performance, with a single achiral SFC method (4.6 × 250 mm, 3.0 μm GreenSep Ethyl Pyridine, 25 mM isobutylamine in methanol/CO₂) affording good separation for all samples. Four of these mixtures were also resolved by achiral SFC on the Luna HILIC and chiral SFC Chiralpak IB columns using methanol or ethanol with 25 mM isobutylamine as polar modifiers. Modifications of standard chromatography screening conditions afforded fast separation methods (from 1 to 5 min) for baseline resolution of all components of each of these challenging sets of closely related compounds.     

Fast Separation Method Development for Supercritical Fluid Chromatography Using an Autoblending Protocol

Supercritical fluid chromatography (SFC) is a powerful separation technique particularly in the area of enantioseparations. With rapid analysis speed, wide polarity compatibility, higher column efficiency and lower cost of the mobile phase, SFC is regarded as a better choice than high-performance liquid chromatography for drug discovery. In the development of separation method, the choice of modifier and/or additive is the key point of optimum separation. However, such screening of SFC is typically time-consuming. In this study, an autoblending protocol was introduced to speed up the modifier and/or additive screening process, which was performed on a separate programmable gradient proportioning system. The protocol prepares mobile phases on the fly to speed up the screening of modifiers and/or additives and reduces the waste of solutions. Furthermore, by switching mobile phase in the same run, separation of different types of compounds could also be achieved. This system was successfully applied to screen modifier–additive combinations of three alkaloids and three polyphenols by switching to two mobile phase conditions, as well as by a ternary additive mobile phase on an SFC system. The proposed protocol allows fast separation method development of SFC, which was proved to be rapid, simple, and reproducible.

     

Fast Separation Method Development for Supercritical Fluid Chromatography Using an Autoblending Protocol

Supercritical fluid chromatography (SFC) is a powerful separation technique particularly in the area of enantioseparations. With rapid analysis speed, wide polarity compatibility, higher column efficiency and lower cost of the mobile phase, SFC is regarded as a better choice than high-performance liquid chromatography for drug discovery. In the development of separation method, the choice of modifier and/or additive is the key point of optimum separation. However, such screening of SFC is typically time-consuming. In this study, an autoblending protocol was introduced to speed up the modifier and/or additive screening process, which was performed on a separate programmable gradient proportioning system. The protocol prepares mobile phases on the fly to speed up the screening of modifiers and/or additives and reduces the waste of solutions. Furthermore, by switching mobile phase in the same run, separation of different types of compounds could also be achieved. This system was successfully applied to screen modifier–additive combinations of three alkaloids and three polyphenols by switching to two mobile phase conditions, as well as by a ternary additive mobile phase on an SFC system. The proposed protocol allows fast separation method development of SFC, which was proved to be rapid, simple, and reproducible.     

Possibility of predicting separations in supercritical fluid chromatography with the solvation parameter model

In order to obtain a selection of optimal chromatographic columns for the separation of chlorotriazine pesticides in packed column supercritical fluid chromatography (pSFC), a multi-criteria approach is applied. For this purpose, prediction of the separations is carried out, based on quantitative structure–retention relationships, then Derringer's desirability function is proposed to determine the stationary phase that will result in the most desirable separation. The best SFC separation obtained was then optimized using a mobile phase gradient. Besides, the accuracy of the solvation parameter model as SFC retention predictive model is assessed.     

Feasibility of ultra high performance supercritical neat carbon dioxide chromatography at conventional pressures

The implementation of columns packed with sub-2 μm particles in supercritical fluid chromatography (SFC) is described using neat carbon dioxide as the mobile phase. A conventional supercritical fluid chromatograph was slightly modified to reduce extra column band broadening. Performances of a column packed with 1.8 μm C18-bonded silica particles in SFC using neat carbon dioxide as the mobile phase were compared with results obtained in ultra high performance liquid chromatography (UHPLC) using a dedicated chromatograph. As expected and usual in SFC, higher linear velocities than in UHPLC must be applied in order to reach optimal efficiency owing to higher diffusion coefficient of solutes in the mobile phase; similar numbers of theoretical plates were obtained with both techniques. Very fast separations of hydrocarbons are presented using two different alkyl-bonded silica columns.