Capillary columns with in situ formed porous monolithic packing for micro high-performance liquid chromatography and capillary electrochromatography
Capillary columns with in situ formed porous monolithic packing for micro high-performance liquid chromatography and capillary electrochromatography
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DOI：
10.1016/s0021-9673(99)00697-4
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发表时间：
1999-09-03
影响因子：
4.1
通讯作者：
Horváth, C
中科院分区：
文献类型：
--
作者：
Gusev, I;Huang, X;Horváth, C
用硅烷化的熔融石英毛细管制备了具有整体固定相的毛细管柱，该毛细管柱的内径为75 μ m，在合适的致孔剂存在下，通过二乙烯基苯与苯乙烯或乙烯基苄基氯的原位共聚而制备。在这项研究中的多孔整体支持直接使用或功能化的表面，以获得一个固定相，这是适合于通过毛细管电色谱（CEC）的肽分离。整体柱的主要优点如下。它们不需要保持玻璃料，它们没有在高电场中可能被逐出的带电粒子，并且它们具有相对高的渗透性和稳定性。尽管这种色谱柱是专门为CEC设计的，但它们也可应用于微型高效液相色谱（mu-HPLC）。采用五种不同的致孔剂制备整体柱，检查其渗透性和孔隙率。熔融石英毛细管的灵活性没有受到整体填料的不利影响，并且柱的寿命是令人满意的。这也可能是由于聚合技术，其导致整料的流体不可渗透的外层，其阻止熔融二氧化硅表面和液体移动的相之间的接触。对于最有前途的柱，电导率比和简化的货车Deemter方程的参数，无论是在CL-HPLC和CEC，进行了评价。结果发现，在CEC中的整体柱的效率显着高于在CL-HPLC中以相同的方式观察到与具有常规颗粒填料的毛细管柱。这是由于相对于粘性流，电渗流（EHF）的带加宽的松弛。因此，在CEC中也可以放宽对获得高效率的高填充均匀性的要求。用毛细管电色谱法分离血管紧张素型多肽，色谱柱填充有固定的正辛基链和表面的季铵基团的整体固定相。常规获得约8 μ m的板高度。分离的机理是基于带正电荷的肽的电泳迁移、色谱保留和电泳迁移之间的相互作用。复杂的迁移过程的结果，与高度非线性依赖的有机改性剂和盐浓度的迁移时间，不能解释经典的色谱或电泳的框架内。(C)1999 Elsevier Science B. V.保留所有权利。
Capillary columns with monolithic stationary phase were prepared from silanized fused-silica capillaries of 75 mu m ID. by in situ copolymerization of divinylbenzene either with styrene or vinylbenzyl chloride in the presence of a suitable porogen. The porous monolithic support in this study was used either directly or upon functionalization of the surface to obtain a stationary phase that was appropriate for the separation of peptides by capillary electrochromatography (CEC). The main advantages of monolithic columns are as follows. They do not need retaining frits, they do not have charged particles that can get dislodged in high electric field, and they have relatively high permeability and stability. Whereas such columns are designed especially for CEC, they find application in micro high-performance liquid chromatography (mu-HPLC) as well. Five different porogens were employed to prepare the monolithic columns that were examined for permeability and porosity. The flexibility of fused-silica capillaries was not adversely affected by the monolithic packing and the longevity of the columns was satisfactory. This may also be due to the polymerization technique, which resulted in a fluid-impervious outer layer of the monolith that precluded contact between the fused-silica surface and the liquid mobile phase. For the most promising columns, the conductivity ratios and the parameters of the simplified van Deemter equation, both in CL-HPLC and CEC, were evaluated. It was found that the efficiency of the monolithic columns in CEC was significantly higher than in CL-HPLC in the same way as observed with capillary columns having conventional particulate packing. This is attributed to the relaxation of band-broadening with electroosmotic flow (EOF) with respect to that with viscous flow. It follows then that the requirement of high packing uniformity to obtain high efficiency may also be relaxed in CEC. Angiotensin-type peptides were separated by CEC with columns packed with a monolithic stationary phase having fixed n-octyl chains and quaternary ammonium groups at the surface. Plate heights of about 8 mu m were routinely obtained. The mechanism of the separation is based on the interplay between EOF, chromatographic retention and electrophoretic migration of the positively charged peptides. The results of the complex migration process, with highly nonlinear dependence of the migration times on the organic modifier and the salt concentration, cannot be interpreted within the framework of classical chromatography or electrophoresis. (C) 1999 Elsevier Science B.V. All rights reserved.