Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA.
J Chromatogr A. 2012 Aug 24;1252:31-44. doi: 10.1016/j.chroma.2012.05.072. Epub 2012 Jun 15.
The column-to-column repeatability of the mass transfer mechanism in columns packed with sub-3μm shell particles was investigated. The parameters of this mechanism were measured for twelve columns (six 2.1mm×100mm and six 4.6mm×100mm) packed with the same batch of 2.6μm Kinetex-C(18) particles (Phenomenex, CA, USA). For both series, the manufacturer provided columns at different positions in the efficiency distribution given by the quality test control. Three compounds were used, uracil, naphthalene and insulin. The reduced longitudinal diffusion term was measured with the peak parking (PP) method, the reduced solid-liquid mass transfer resistance term was given by a combination of the PP results and a model of effective diffusion in ternary composite materials (non-porous cores, concentric porous shell, and eluent matrix), validated previously. The overall eddy diffusion term was obtained by subtraction of these two HETP terms from the overall reduced HETP measured by numerical integration of the entire peak profiles. The results demonstrate that the dispersion of the column efficiencies is only due to the random nature of the packing process. At the highest reduced velocity achieved, the relative standard deviations (RSDs) of the eddy diffusion term for the 2.1mm I.D. columns were ca. 7% and 3% for the low molecular weight compounds and for insulin, respectively. For the 4.6mm I.D. columns, these RSDs were 15% and 5%, respectively. The larger RSDs for the 4.6mm I.D. columns is explained by the exceptionally low value of the eddy diffusion term.
考察了装填亚 3μm 壳颗粒的色谱柱中传质机理的柱间重现性。该机理的参数通过十二根色谱柱（六根 2.1mm×100mm 和六根 4.6mm×100mm）进行了测量，这些色谱柱均装填了相同批次的 2.6μm Kinetex-C(18)颗粒（Phenomenex，CA，美国）。对于这两个系列，制造商在质量测试控制给出的效率分布的不同位置提供了柱子。使用了三种化合物，尿嘧啶、萘和胰岛素。通过峰停（PP）法测量了减少的纵向扩散项，减少的固液传质阻力项由 PP 结果与先前验证的三元复合材料（无孔核、同心多孔壳和洗脱剂基质）有效扩散模型的组合给出。通过从通过数值积分整个峰形获得的整体减少的 HETP 中减去这两个 HETP 项，获得了整体涡流扩散项。结果表明，柱效率的分散仅归因于填充过程的随机性质。在所达到的最高减少速度下，2.1mm ID 柱的涡流扩散项的相对标准偏差（RSD）对于低分子量化合物和约为 7%，对于胰岛素约为 3%。对于 4.6mm ID 柱，这些 RSD 分别约为 15%和 5%。4.6mm ID 柱的较大 RSD 可归因于涡流扩散项的异常低值。
