Blue Laura E, Jorgenson James W
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
J Chromatogr A. 2015 Feb 6;1380:71-80. doi: 10.1016/j.chroma.2014.12.055. Epub 2014 Dec 27.
The predicted advantages of superficially porous particles over totally porous particles are decreased eddy dispersion, longitudinal diffusion, and resistance to mass transfer contributions to the theoretical plate height. While sub-2 micron superficially porous particles are commercially available, further improvements in performance are predicted by decreasing the particle diameter and decreasing the porous layer thickness. 1.1 μm superficially porous particles with 187Å pores have been synthesized using a layer-by-layer method tuned for production of smaller diameter particles. Following synthesis, these particles were packed into 30 μm i.d. capillary columns and their chromatographic performance evaluated using electrochemical detection. Based on the initial studies, the column efficiency did not meet theory, but was similar to the commercially available products tested. It is believed that the column packing process plays a critical role in the sub-par column performance. To determine if column efficiency could be predicted by solvent-particle interactions, in-solution optical microscopy and sedimentation velocity of particles in various slurry solvents were investigated and compared to column performance. Aggregating slurry solvents, such as methanol were found to produce columns with increased efficiency. The hmin for a column packed with an acetone slurry and a methanol slurry at 3mg/mL were found to be 6.3 and 3.5, respectively. Increasing the slurry concentration to 25mg/mL further improved the efficiency, producing a column with an hmin of 2.6. These efficiency results were accurately predicted by in-solution optical microscopy.
与全多孔颗粒相比，表面多孔颗粒预计具有的优势包括减少涡流扩散、纵向扩散以及对理论塔板高度的传质贡献阻力。虽然亚2微米表面多孔颗粒已有商业产品，但预计通过减小粒径和减小多孔层厚度可进一步提高性能。使用针对生产更小粒径颗粒进行调整的逐层方法合成了具有187Å孔隙的1.1μm表面多孔颗粒。合成后，将这些颗粒填充到内径30μm的毛细管柱中，并使用电化学检测评估其色谱性能。基于初步研究，柱效未达到理论值，但与测试的市售产品相似。据信柱填充过程在低于标准的柱性能中起关键作用。为了确定柱效是否可以通过溶剂 - 颗粒相互作用来预测，研究了颗粒在各种浆料溶剂中的溶液内光学显微镜和沉降速度，并与柱性能进行比较。发现聚集性浆料溶剂，如甲醇，可产生效率更高的柱。发现用3mg/mL丙酮浆料和甲醇浆料填充的柱的最小板高分别为6.3和3.5。将浆料浓度提高到25mg/mL可进一步提高效率，产生最小板高为2.6的柱。这些效率结果通过溶液内光学显微镜得到了准确预测。
