毛细管硅胶基质整体柱的制备及其电色谱性能研究

采用热引发一步法制备了毛细管电色谱硅胶基质整体柱。通过使用表面活性剂(十二烷基磺酸钠)增加了反应液中两相之间的相互溶解,使得反应液最终成为均相溶液,实现了硅胶整体柱的均相聚合制备。所制备的均相硅胶整体柱内部结构更加均匀,大大提高了分离度。评价了该整体柱的电色谱性能,深入探讨了有机溶剂比例、pH值、电压以及温度等电色谱操作条件对电渗流、保留机理和柱效的影响。在该均相硅胶基质整体柱上成功地分离了9种中性物质(硫脲、苯、甲苯、乙基苯、正丙苯、萘、正丁基苯、芴和蒽)以及7种中性、酸性和碱性物质(硫脲、邻氨基酚、苯酚、苯、邻甲苯胺、α-萘胺和2,4-二氯苯胺)。该柱对硫脲的柱效超过110000塔板/m。     

毛细管电色谱硅胶整体柱的制备与性能研究

以甲基丙烯酸丙酯基三甲氧基硅烷(MPTMS)为单体,甲苯为致孔剂,偶氮二异丁腈(AIBN)为引发剂,盐酸为催化剂,采用热引发法制备毛细管电色谱硅胶整体柱.在反相毛细管电色谱条件下,对中性化合物硫脲,苯,萘,芴,蒽实现了基线分离了.柱效超过100,000 plates/m.探讨了该柱的制备条件如单体比例,毛细管内径,制柱反应时间对分离的影响,并且在电色谱条件下考察了有机溶剂比例,pH值,电压和温度对分离的影响.     

高内相乳液法制备整体柱及其分离性能研究

建立了高内相乳液(HIPE)法制备以甲基丙烯酸十二烷酯为功能单体(LMA),二乙烯基苯(DVB)为交联剂的新型毛细管电色谱整体柱。polyHIPE整体柱利用扫描电镜与BET进行了表征,表明了制备的整体柱具有较大的孔径与较好的比表面积,更好的通透性,可更好地满足高效快速分离分析的需要。实验中K2S2O8不仅可以作为引发剂,同时加热后残基能为固定相提供电渗流。优化表面活性剂span80含量、W/O比例对整体柱制备的影响,以硫脲与苯系物为目标化合物考察了整体柱的分离性能与效果。该方法用实际水样品苯系物分析,取得良好的效果。     

析因设计法优化制备聚(DVB)型整体柱及分离小分子物质的应用

以二乙烯基苯(DVB)为单体,十二烷醇和甲苯为制孔剂,在引发剂偶氮二异丁腈(AIBN)的作用下,直接以φ4.6×50mm色谱柱为模具,通过原位聚合制备了聚(二乙烯基苯)型整体柱.通过析因设计,以十二烷醇占反应混合物体积比,二乙烯基苯占反应混合物体积比,偶氮二异丁腈所占聚合物质量比3因素,以整体柱对小分子的分离度为响应指标进行了3因素2水平全析因实验.结果表明,引发剂的量对分离度的影响最大,其次为十二烷醇占反应混合物体积比与引发剂占聚合物质量比的交互作用和3因素交互作用,而其他效应,如十二烷醇占反应混合物体积比,DVB占反应混合物体积比,十二烷醇与DVB的交互作用,DVB与引发剂的交互作用的影响较小,可以忽略;从而得到了分离小分子物质的最优配方;通过测定整体柱的比表面积,孔径和孔容分布对其进行表征.所制备的整体柱,能够通过高效液相色谱系统对苯,乙苯和萘这3种小分子物质进行分离.分离条件为:100×4.6mm I.D.色谱柱,流动相为乙腈:水=80:20(v/v),流速1mL/min,检测峰值254nm.色谱柱背压5MPa,分离时间10min.     

新型亲水整体柱的制备及其在毛细管液相色谱和加压电色谱中的应用

以N,N-二甲基-N-甲基丙烯酰胺基丙基-N,N-二甲基-N-丙烷磺酸内盐(SPP)为单体,季戊四醇三丙烯酸酯(PETA)为交联剂,偶氮二异丁腈(AIBN)为引发剂及两类不同的致孔剂(乙醇/乙二醇和甲醇/1,4-丁二醇)制备了两种新型亲水性整体柱。为了获得理想的柱效、电渗流速度和渗透性,对制备整体柱的各反应物配比进行了研究和优化。比较了两种整体柱在渗透性和分离样品方面的性能,结果表明,以乙醇/乙二醇为致孔剂制备的整体柱在柱效、分离度方面优于以甲醇/1,4-丁二醇为致孔剂制备的整体柱,但在渗透性方面不及后者。探讨了流动相中盐浓度对核苷类样品保留的影响,发现当甲酸铵浓度从10 mmol/L增加到70 mmol/L时,核苷样品的保留因子呈现先增加后减小的状态。将制备的整体柱用于毛细管液相色谱和加压电色谱分别分离胺类、酚类和核苷类样品,获得了理想的分离效果。在分离酚类和核苷类混合样品时,发现加压毛细管电色谱在分离度和分离速度上均优于毛细管液相色谱。     

光聚合法快速制备甲基丙烯酸酯类毛细管整体柱

采用甲基丙烯酸正丁酯(BMA)为功能单体, 乙二醇二甲基丙烯酸酯(EDMA)为交联剂, 正丙醇、1,4-丁二醇和水为致孔剂, Irgacure 1800为引发剂, 在毛细管内采用光引发原位聚合150 s快速制备了有机聚合物整体柱. 分别采用电色谱(CEC)、加压电色谱(p-CEC)和低压色谱(LPLC)模式对所制备的整体柱进行了性能评价, 基线分离了硫脲、甲苯、萘和联苯, 在加压电色谱(p-CEC)模式下硫脲的最低理论塔板高度达到了8.0 μm. 扫描电镜结果表明, 整体材料在毛细管柱中形成并与毛细管内壁结合紧密.     

一种聚甲基丙烯酸酯类亲水作用毛细管电色谱整体柱的制备与评价

以2-羟基乙基甲基丙烯酸酯(HEMA)为单体,乙二醇二甲基丙烯酸酯(EDMA)为交联剂,制备了亲水分离模式的聚HEMA-co-EDMA新型毛细管电色谱(CEC)整体柱。考察了整体柱的结构特征及其CEC性能,研究了极性物质的保留行为,并对其可能的保留机理进行了探讨。所制备的整体柱稳定性好,固定相表面带有极性羟基功能团,不仅能提供亲水相互作用位点,且能吸附流动相中的阴离子产生阳极电渗流(EOF)。在流动相中乙腈含量较高(＞62%,体积分数)的条件下,整体柱表现出典型的亲水作用,实现了对核苷、碱基和苯胺类带有碱性的强极性化合物的高效分离,并成功分离了苯酚类、苯甲酸类等中性或酸性的极性化合物。     

丙烯胺-β-环糊精电色谱整体柱的性能评价及应用

以丙烯胺-β-环糊精(Allylamine-β-CD)为功能单体,采用一步键合法制备毛细管电色谱手性整体柱,并考察了整体柱的制备条件。在毛细管电色谱(CEC)模式下,以苯丙氨酸为对象,考察了整体柱的分离能力,同时考察缓冲溶液pH,柱温,分离电压对拆分的影响。苯丙氨酸的拆分达到了基线分离,并在优化条件下,应用整体柱对盐酸去甲苯福林和愈创甘油醚对映体进行拆分,均达到基线分离。同时,以硫脲为电渗流标记物,测得整体柱的理论塔板数达87488板/m,并且可持续使用16 h,可间歇使用3个月以上,仍具有良好的柱效。     

石英砂整体微柱的制备及其反相电色谱分离研究

在2.2mm内径的石英管中,采用正硅酸四乙酯水解的溶胶-凝胶法合成了填充细石英砂的高比表面积电色谱整体柱,并用正辛基三乙氧基硅烷键合制备反相色谱固定相.填充细石英砂的电色谱整体柱抑制了大柱径引起的电流热效应,采用电渗流驱动流动相,分离了苯酚和苯,实验证明该整体微柱用于电色谱分离和改善浓度检出限的可行性.     

联二萘酚印迹的电色谱整体柱的制备

讨论了分子印迹毛细管电色谱整体柱的制备.联二蔡酚作为印迹分子在热引发条件下聚合,其中甲基丙烯酸为功能单体,二甲基丙烯酸乙二醇酯为交联剂,甲苯和异辛烷为致孔剂.考察了聚合参数对整体柱通透性及手性分离的影响.联二萘酚对映体在印迹整体柱上得到了基线分离,Rs值可达1.8.     

Novel preparation of monolithic imprinted columns for electrochromatographic separation by photopolymerization

A monolithic molecularly imprinted polymer with specific recognition ability for 4-hydroxybenzoic acid (4-HBA) was prepared by in situ photopolymerization, using methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linking agent, toluene and isooctane as porogenic solvents and Irgacure 1800 as an initiator. Baseline separation of isomers of hydroxybenzoic acid was achieved in less than 8 min on this monolithic column using 4-HBA as template, but not on the blank polymer. Furthermore, some neutral compounds could also be baseline-separated on the imprinted polymer column in the mode of pressure-driven capillary electrochromatography.     

Optimized preparation of poly(styrene-co- divinylbenzene-co-methacrylic acid) monolithic capillary column for capillary electrochromatography

Preparation of a poly(styrene-co-divinylbenzene-co-methacrylic acid) monolithic stationary phase for the use in capillary electrochromatography (CEC) has been improved by optimizing the polymerization conditions. It is observed that the reaction time strongly affects column efficiency, while the proportion of isooctane in porogen influences peak symmetry of some solutes seriously. The lifetime of the monolithic columns prepared mainly depends on the pH of buffers used. Reproducibility of electroosmotic flow (EOF) from batch to batch columns are lower than 2.8% relative standard deviation. Unlike other types of capillary electrochromatographic monoliths, a pH-dependent EOF was observed on this type of column. Separation of various types of compounds including aromatic hydrocarbons, hormones, anilines, basic pharmaceuticals, and peptides was achieved. The facile preparation and wide application of this monolithic column may make styrene-based polymer a potential stationary phase in CEC.     

Fast separations of chiral β-blockers on a cellulose tris(3,5-dimethylphenylcarbamate)-coated zirconia monolithic column by capillary electrochromatography

Cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) is an excellent chiral selector for enantioseparation of a wide variety of chiral compounds. The monolithic chiral columns are becoming popular in liquid chromatography and capillary electrochromatography. In this work, we present the fast separation of chiral β-blockers on a CDMPC-modified zirconia monolithic column by capillary electrochromatography (CEC). The porous zirconia monolithic capillary column was prepared by using the sol-gel technology and then zirconia surface modified with CDMPC. The enantioseparations were performed in reversed-phase (RP) eluents of a phosphate solution (pH 4.4) modified with acetonitrile or alcohol. The enantioseparations of a set of eight chiral β-blockers were achieved in less than one minute. Influences of the applied voltage, column temperature, concentration of acetonitrile and the type of alcohol as the organic modifier in the mobile phase, and sample injection time on enantioseparation were investigated. CEC separations at the applied voltage of 10 kV and 15 °C in the ACN-modified mobile phase provided the best resolutions for the analytes studied. Run-to-run and day-to-day repeatabilities of the column in the RP-CEC separation were less than 1 and 2%, respectively.     

烯丙基-β-环糊精基手性毛细管电色谱整体柱的一步法制备及其性能

以烯丙基-β-环糊精、甲基丙烯酸缩水甘油酯和乙二醇二甲基丙烯酸酯为功能单体,一步键合制备了环糊精聚合物毛细管整体柱.在电色谱模式下18种氨基酸对映体得到成功分离.研究发现,将修饰的环糊精衍生物作为功能单体制备出的毛细管整体柱对疏水性,含氨基和苯环的手性化合物具有良好的保留行为,并具有良好的稳定性和重现性.新型电色谱柱也被应用于手性药物的分离.     

Photografted methacrylate‐based monolithic columns coated with cellulose tris(3,5‐dimethylphenylcarbamate) for chiral separation in CEC

A chiral capillary monolithic column for enantiomer separation in capillary electrochromatography was prepared by coating cellulose tris(3,5‐dimethylphenylcarbamate) on porous glycidyl methacrylate‐co‐ethylene dimethacrylate monolith in capillary format grafted with chains of [2(methacryloyloxy)ethyl] trimethylammonium chloride. The surface modification of the monolith by the photografting of [2(methacryloyloxy)ethyl] trimethylammonium chloride monomer as well as the coating conditions of cellulose tris(3,5‐dimethylphenylcarbamate) onto the grafted monolithic scaffold were optimized to obtain a stable and reproducible chiral stationary phase for capillary electrochromatography. The effect of organic modifier (acetonitrile) in aqueous mobile phase for the enantiomer separation by capillary electrochromatography was also investigated. Several pairs of enantiomers including acidic, neutral, and basic analytes were tested and most of them were partially or completely resolved under aqueous mobile phases. The prepared monolithic chiral stationary phases exhibited a good stability, repeatability, and column‐to‐column reproducibility, with relative standard deviations below 11% in the studied electrochromatographic parameters.     

聚丙烯酸酯类毛细管整体柱的制备及其在加压毛细管电色谱中的应用

毛细管电色谱(CEC)是毛细管电泳(CE)和微径液相色谱(micro—HPLC)技术的结合,是集CE的电子迁移机制和micro-HPLC的分配分离机理发展起来的一种高效微分离技术．CEC以塞子流型的电渗流代替抛物线流型的压力流,具有CE的高效性,能够分离电中性化合物而具有HPLC的高选择性．     

Enantioseparation on cellulose dimethylphenylcarbamate-modified zirconia monolithic columns by reversed-phase capillary electrochromatography

This work reports the preparation of monolithic zirconia chiral columns for separation of enantiomeric compounds by capillary electrochromatography (CEC). Using sol–gel technology, a porous monolith having interconnected globular-like structure with through-pores is synthesized in the capillary column as a first step in the synthesis of monolithic zirconia chiral capillary columns. In the second step, the surface of the monolith is modified by coating with cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) as the chiral stationary phase to obtain a chiral column (CDMPCZM). The process of the preparation of the zirconia monolithic capillary column was investigated by varying the concentrations of the components of the sol solution including polyethylene glycol, water and acetic acid. CDMPCZM is mechanically stable and no bubble formation was detected with the applied current of up to 30 μA. The enantioseparation behavior of the CDMPCZM columns was investigated by separating a set of 10 representative chiral compounds by varying the applied voltage and pH and organic composition of the aqueous organic mobile phases.     

Mechanism of molecular recognition on molecular imprinted monolith by capillary electrochromatography

The recognition mechanism of molecularly imprinted polymer (MIP) in capillary electrochromatography (CEC) is complicated since it possesses a hybrid process, which comprises the features of chromatographic retention, electrophoretic migration and molecular imprinting. For an understanding of the molecular recognition of MIP in CEC, a monolithic MIP in a capillary with 1,1'-binaphthyl-2,2'-diamine (BNA) imprinting was prepared by in situ copolymerization of imprinted molecule, methacrylic acid and ethylene glycol dimethacrylate in porogenic solvent, a mixture of toluene-isooctane. Strong recognition ability and high column performance (theory plates was 43,000 plates/m) of BNA were achieved on this monolithic MIP in CEC mode. In addition, BNA and its structural analogue, 1,1'-bi-2, 2'-naphthol, differing in functional groups, were used as model compounds to study imprinting effect on the resultant BNA-imprinted monolithic column, a reference column without imprinting of BNA and a open capillary. The effects of organic modifier concentration, pH value of buffer, salt concentration of buffer and column temperature on the retention and recognition of two compounds were investigated. The results showed that the molecular recognition on MIP monolith in CEC mode mainly derived from imprinting cavities on BNA-imprinted polymer other than chromatographic retention and electrophoretic migration.     

Electrochromatography with a 2.7 mm inner diameter monolithic column

Monolithic columns of 2.7 mm I.D. have been prepared and used in electrochromatography (EC) separation. Although capillary electrochromatography (CEC) has higher separation efficiency, it displays some shortcomings, such as limited sample loadability and restricted concentration detectability etc. In this paper, we investigate the feasibility of EC separation with millimeter diameter monolithic columns. By using a designed preparation method of monolithic column packed with about 150 microm quartz sand, the effect of Joule heating can be reduced, and the processes of frit making and column packing can be avoided. The concentration detectability of the EC is improved comparing with that of CEC. Moreover, the separation efficiency of 52,000 plates/m was achieved with a 70 mm length and 2.7 mm I.D. monolithic column.