某些酚类的高温液相色谱行为

建立了高温液相色谱系统,在高温条件下,采用甲醇-水作为流动相,在Polymerx RP-1聚合物(PSDVB)色谱柱上考察了6种酚类样品的色谱行为.实验条件:温度40～160 ℃,流速0.2～5.5 mL/min,流动相中甲醇浓度范围40%～80%.考察了温度、流速和流动相组成对酚类样品的保留、分辨、柱效和系统压力的影响,探讨了酚类样品在聚合物柱上的热力学行为.温度升高2.35℃大约相当于流动相中甲醇浓度增加1%,可以通过改变色谱柱温度调节样品保留和改变选择性.柱温升高,降低了流动相的粘度,允许在高温条件下使用较高的流速实现快速分离.在160℃、V(甲醇):V(水)=40:60,为流动相和3 mL/min流速条件下,可于2.5 min内实现6种酚类的完全分离.     

黄酮类化合物的超临界流体色谱分离

利用超临界流体色谱成功地分离了黄酮类化合物，研究了流动相组成，柱条件，压力及温度的影响。发现流动相组成是影响色谱分离的最主要因素；其次，色谱柱条件也是影响分离的一个很重要的因素，硅胶基质的键合苯基柱比较适合于极性黄酮类化合物的分离。     

手性高效液相色谱法检测恩替卡韦中光学异构体杂质的含量

采用Chiralpak AD-H手性柱(250 mm×4.6 mm, 5 μm),建立了正相高效液相色谱(NP-HPLC)法直接拆分恩替卡韦与其光学异构体的方法.考察了流动相组成、酸碱性对柱效、分离度、保留时间等参数的影响.经优化,以正己烷-异丙醇-乙醇-三氟乙酸-三乙胺(70∶ 12∶ 18∶ 0.05∶ 0.05,V/V)为流动相,流速0.5 mL/min;检测波长261 nm.在此条件下,恩替卡韦与光学异构体分离度>4.2;光学异构体的检出限为0.12 mg/L,在0.25～4.0 mg/L浓度范围内有良好的线性关系;日内与日间精密度RSD<4.0%;按标准加入法计算,加样回收率在87.0%～100.8%之间; RSD<3.0%;按外标法计算,加样回收率在98.2%～110.4%之间; RSD<3.0%.本方法可作为恩替卡韦原料药中光学异构体杂质限量的控制方法.     

酰胺类手性液相色谱柱对烯唑醇光学异构体的直接拆分

以正己烷-12-二氯乙烷为流动相,添加乙腈为改性剂,在酰胺类手性液相色谱柱上实现了对烯唑醇光学异构体的直接拆分.探讨了色谱柱、温度和乙腈的含量对拆分效果的影响,优化了色谱条件.实验结果显示:单独使用KR100-5CHI-DMB色谱柱时,烯唑醇中的光学异构体仅稍微分离;而单独使用Chirex 3001时,烯唑醇中的光学异构体则不分离;当KR100-5CHI-DMB与Chirex 3001串联使用时,烯唑醇中光学异构体能够得到很好的分离;在流动相中加入少量的乙腈作为极性添加剂,有助于改善异构体的分离度.当流动相为正己烷-12-二氯乙烷-乙腈(体积比8 ∶ 1 ∶ 1),流速1.0 mL/min,检测波长254 nm,柱温10 ℃时,烯唑醇中光学异构体得到很好的分离,分离度(R)为3.26.结果表明,酰胺类手性液相色谱柱能有效分离烯唑醇的光学异构体,方法简便、快速.     

高效液相色谱-串联质谱法结合多糖衍生物手性固定相拆分氰戊菊酯

建立了以多糖衍生物为手性固定相的高效液相色谱-串联质谱(HPLC-MS/MS)直接拆分氰戊菊酯对映体的方法。在反相液相色谱条件下,考察了手性固定相的种类、流动相组成、柱温、流速对氰戊菊酯4个立体异构体分离的影响。同时,利用热力学方法对氰戊菊酯的立体异构体与固定相之间的色谱保留和分离的热力学机理进行了探讨。结果表明:采用Lux Cellulose-3(纤维素-三(4-甲基苯甲酸酯))手性色谱柱,在以流动相为乙腈-水(5 mmol/L甲酸铵)=(55:45,V:V)流速0.4 mL/min,柱温30℃的条件下,可在14 mins内实现氰戊菊酯4个立体异构体的基线分离。拓展了HPLC-MS/MS在菊酯类手性农药对映体分离及检测上的应用。     

盐酸托莫西汀中S-异构体杂质含量的柱前衍生高效液相色谱法测定

以2,3,4,6-四-O-乙酰基-β-D-葡萄糖异硫氰酸酯(GITC)为柱前手性衍生化试剂,建立了柱前衍生化反相高效液相色谱(RP-HPLC)法测定盐酸托莫西汀中S-异构体杂质的方法。考察了碱化与衍生化试剂的浓度及反应时间对衍生化产率的影响,以及流动相组成对柱效、分离度、保留时间的影响,并讨论了结构因素对手性衍生和分离的影响。采用Agilent Zorbax SB-C18(250 mm×4.6 mm,5μm)色谱柱,以乙腈-四氢呋喃-水(体积比为41∶14∶45)为流动相,流速1.0 mL/min;检测波长254 nm,柱温35℃。在优化实验条件下,盐酸托莫西汀与S-异构体的分离度R1.5;S-异构体的检出限为0.15 mg/L,在0.5~8 mg/L范围内线性良好;精密度RSD为1.8%;按标准加入法计算,加标回收率为92%~99%;按外标法计算,加标回收率为94%~102%。该方法简便、可靠,可作为盐酸托莫西汀原料药中S-异构体杂质限量的质控方法。     

S-羟丙基-β-环糊精手性柱上联二萘胺和联二萘酚光学异构体的反相高效液相色谱法直接分离

在S-羟丙基-β-环糊精手性柱(Cyclobond Ⅰ 2000 SP)上用反相高效液相色谱法研究了2,2'-二氨基-1,1'-联萘(联二萘胺)和2,2'-二羟基-1,1'-联萘(联二萘酚)光学异构体的分离,考察了流动相组成、流速以及柱温等对联二萘胺和联二萘酚光学异构体分离的影响.分离联二萘胺和联二萘酚光学异构体的色谱条件:甲醇-水(体积比30 : 70)为流动相,柱温分别为25 ℃和20 ℃,流速分别为1.0、0.1 mL/min.在选定的色谱条件下,联二萘胺和联二萘酚光学异构体的分离度(R)和分离因子(α)分别为2.33、1.26和1.22、1.10.通过分离过程中的热力学参数的计算,探讨S-羟丙基-a-环糊精对联二萘胺和联二萘酚的手性识别机理,证实了联二萘胺和联二萘酚光学异构体的分离是焓驱动过程.     

环糊精衍生物固定相毛细管气相色谱法分离甲酚位置异构体

采用了环糊精衍生物固定相毛细管气相色谱法对甲酚位置异构体进行分离。着重考察了气相色谱中柱头压、柱温、检测器温度、进样器温度对保留时间和峰面积的精密度的影响,并通过正交实验优化色谱条件使峰面积的相对标准偏差小于1%,异构体达到基线分离。     

反相-高效液相色谱手性流动相添加剂法测定酸奶及含乳饮料中乳酸对映异构体

选取2,3,6-三甲基-β-环糊精（TM-β-CD）作为流动相手性添加剂,建立了采用反相高效液相色谱法分离酸奶及含乳饮料中乳酸异构体的方法。实验采用hypersil ODS2-C18（250&#215;5．0mm,5μm）色谱柱,以0．5mmol／L PH2．5的TM-β-CD（含4．5mmol／L H2SO4）作为流动相,流速为1．0mL／min,紫外检测波长为210nm。实验考察了不同色谱柱、柱平衡时间、手性流动相添加剂浓度及pH值对分离效果的影响,并进一步研究了方法的线性范围、检出限、精密度及回收率。     

超临界流体色谱法分离生育酚同系物

用超临界流体色谱法进行了生育酚异构体的分离研究。在实验温度303．15K～343．15K和压力14～22MPa范围内，考察了ODS柱上温度、压力和密度与容量因子和选择性的关系，得到了生育酚在超临界色谱中的最佳分离条件：温度为343．15K，压力为20MPa，CO2流量750mL/min。     

C18柱串联冠醚手性柱高效分离3种芳香族氨基酸对映体

将C18柱与手性冠醚柱串联,建立了一种反相高效液相色谱法用于3种芳香族氨基酸对映体同时拆分的方法.考察了反相色谱流动相的组成、pH值、柱温、流速对对映体拆分的影响.实验结果表明,当流动相为HClO4-乙睛溶液(86:14,V/V,pH 2.0)、柱温20℃、流速0.4 mL/min时,3种氨基酸对映体可获得基线分离.进一步对比了C18柱、冠醚手性柱和串联顺序不同的4种分离模式,结果表明,C18柱不能拆分氨基酸对映体,仅能分离不同种类氨基酸;冠醚手性柱可分离氨基酸映体,但不同种类氨基酸色谱峰出现重叠;串联模式能实现3种氨基酸对映体的基线分离,实现双柱优势互补,而串联顺序对分离影响不大,仅影响色谱峰的峰形.     

Liquid Chromatographic Characteristics of Ethylenethiourea with HPLC Carbon,Chiral, Polymer and Reverse-Phase Bonded Silica Columns

Abstract

Of the columns investigated, the graphitised carbon column provided the best chromatographic characteristics for the highly water-soluble compound ethylenethiourea (ETU). The stability of the carbon column in strongly acidic media permitted the incorporation of the phosphoric acid electrolyte into the 5% acetonitrile-in-water mobile phase. ETU eluted from the column in 200 s as a sharp symmetrical peak at a mobile phase flow rate of 1 mL/min and a column temperature of 35°C. The k' value was 1.72. ETU peak retention times and responses showed excellent repeatability with coefficients of variation of 0.28 and 1.40%, respectively, for 6 replicates with the high performance liquid chromatographic-electrochemical system using the graphitised carbon column. Although ETU eluted as a sharp symmetrical peak with the cyclodextrin chiral columns, their instability at low pH required post-column addition of the phosphoric acid electrolyte solution. ETU chromatographed poorly or degraded on the polymer columns. The chromatographic separation of ETU on the C-8 reverse-phase bonded silica column appeared to be due mainly to residual silanol groups. With the NH₂ bonded silica column ETU eluted immediately after the injection solvent.     

Ultrahigh pressure liquid chromatography using elevated temperature

Fast liquid chromatographic (LC) methods are important for a variety of applications. Reducing the particle diameter (d(p)) is the most effective way to achieve fast separations while preserving high efficiency. Since the pressure drop along a packed column is inversely proportional to the square of the particle size, when columns packed with small particles (<2 microm) are used, ultrahigh pressures (>689 bar) must be applied to overcome the resistance to mobile phase flow. Elevating the column temperature can significantly reduce the mobile phase viscosity, allowing operation at higher flow rate for the same pressure. It also leads to a decrease in retention factor. The advantage of using elevated temperatures in LC is the ability to significantly shorten separation time with minimal loss in column efficiency. Therefore, combining elevated temperature with ultrahigh pressure facilitates fast and efficient separations. In this study, C6-modified 1.0 microm nonporous silica particles were used to demonstrate fast separations using a temperature of 80 degrees C and a pressure of 2413 bar. Selected separations were completed in 30 s with efficiencies as high as 220,000 plates m(-1).     

Liquid chromatography analysis of monosubstituted sulfobutyl ether-beta-cyclodextrin isomers on porous graphitic carbon

The retention behaviour of the three positional isomers of monosubstituted sulfobutyl ether-beta-cyclodextrin was investigated on a porous graphitic carbon (PGC) column. The influence of the mobile phase composition (nature and concentration of organic and electronic modifiers) was studied as well as the effect of column temperature. These hydrophilic and anionic analytes were highly retained on the PGC stationary phase compared to octadecyl bonded phases. The retention is mainly governed by a reversed-phase mechanism with electronic interaction playing a secondary role. An increase in solute retention and efficiency with temperature was observed. Successful isocratic separation with satisfactory baseline resolution of the three isomers of monosubstituted sulfobutyl ether-beta-cyclodextrin was achieved at 75 degrees C on a Hypercarb column by using ammonium acetate as electronic modifier in water-acetonitrile (83:17). The chromatographic methodology developed can be easily used for relative quantification of each isomer within a mixture and can be applied for semi-preparative purification of each one. The evaporative light scattering detector allows the detection of these non UV-visible absorbing molecules.     

Highly efficient high‐performance liquid chromatographic separation of xylene isomers and phthalate acid esters on a homemade DUT‐67(Zr) packed column

In this study, the baseline separations of xylene isomers and phthalate acid esters on a homemade DUT‐67(Zr) packed column were achieved, respectively. The high selectivity for xylene isomers and phthalate acid esters was obtained with the increase in temperature and decrease in the retention time. The hydrophobicity of xylene isomers and phthalate acid esters resulted in the different separation time on the DUT‐67(Zr) packed column. The relative standard deviation values of retention time, peak area, peak height, and half peak width for five repeat separation of the xylene isomers were 0.26–0.35, 2.11–2.26, 1.51–2.03, and 0.29–0.77%, and the values of the phthalate acid esters on DUT‐67(Zr) column were 0.1–0.4, 4.4–5.2, 3.9–6.3, and 0.6–2.1%, respectively. The thermodynamic properties indicated that the separation of xylene isomers was controlled by ΔH and ΔS, but the separation of phthalate acid esters was mainly controlled by ΔS.     

高效液相色谱法分离水田除草剂萘丙胺光学异构体

采用高效液相色谱法分离水田除草剂萘丙胺光学异构体。实验结果表明,在键合（Ｓ）－（＋）－Ｎ－（３,５－二硝基苯甲酰基）苯甘氨酸［３,５－ＤＮＢ－（Ｓ）－（＋）－ＰＧ］手性色谱柱上以正已烷／异丙醇（１００／１０,Ｖ／Ｖ）为流动相时,能较好地分离其萘丙胺的光学异构体,其容量因子分别为５．８１和６．２０;分离因子为１．０８。     

氯丙基键合硅胶固定相色谱性能与应用 I.二取代苯及前列腺素差向异构体的分离

研究了氯丙基键合硅胶固定相的高效液相色谱性能和在分离二取代苯异构体、前列腺素差向异构体方面的应用,探讨了流动相组成、性质、ｐＨ值等对溶质保留和分离的影响,讨论了溶质保留机理和最佳色谱分离条件。对上述异构体进行了良好的分离,而且分离速度比一般的反相色谱体系要好。     

甘脲用作气相色谱固定相的色谱性能研究

甘脲具有双环双脲结构,既是质子给体,又是质子受体,能与溶质产生氢键作用等多种作用力。本文制备了以甘脲作为固定相的填充柱,并对它的色谱性能进行了研究。结果表明:甘脲固定相热稳定性高、柱性能稳定,是一种良好的气相色谱固定相。该固定相对烷烃、卤代烃、芳烃、醇、酯、酮、酸、胺等类物质具有良好的分离能力,尤其是对位置异构体(如二取代苯位置异构体)有较好的分离选择性。本文还初步探讨了甘脲固定相的分离机理。     

A humic acid stationary phase for the high performance liquid chromatography separation of buckminsterfullerenes: theoretical and practical aspects

The influence of the mobile phase composition and column temperature on the chromatographic separation of five buckminsterfullerenes (C60, C70, C76, C78, C84) on a stationary phase based on silica gel with chemically bonded humic acid (Bonded humic acid column (BHAC)) was studied. The retention behavior of the fullerenes was measured under isocratic conditions with different mobile phase compositions, ranging from 0.05-0.70 (v/v) of toluene in cyclohexane. The column temperature was analysed in the range 35-75 °C. The retention factors of the five fullerenes do not depend linearly on the toluene fraction but follow a quadratic relationship. The best chromatographic conditions for baseline separation of the five fullerenes were selected. The retention of the fullerenes on the HA stationary phase was strongly affected by temperature. Positive values of thermodynamic parameters (changes of enthalpy and entropy) were due to the abnormal solubility behaviour of fullerenes in toluene in the temperature range 35-75 °C. The information obtained in this work makes this BHAC very simple to prepare and low cost, useful for fullerene research applications.