About the C term in the van Deemter's equation of plate height in monoliths

作者：Siouffi A M^*

来源：Journal of Chromatography A, 2006, 1126(1-2): 86-94.

DOI：10.1016/j.chroma.2006.05.036

• HPLC
• monoliths
• van Deemter plots
• mass transfer

Monolithic stationary phases provide high rates of mass transfer at low pressure drops and enable much faster separations. Experimental data from published H versus a plots obtained with monolithic columns are compiled with an emphasis on the mass tranfer (C term of the van Deemter equation). Silica-based monoliths of the C18 Chromolith type exhibit a very low C value that does not vary too much within a wide range of flow rates. The C term is a function of retention, temperature, molecular weight of the solute and mesopore size. Silica-based monoliths of capillary format exhibit a slightly higher C value which slightly increases with increasing flow rates. The key parameter is the through-pore size/skeleton size ratio. Experimental data on polymer-based monoliths retrieved from the literature mostly concern acrylate-based material in a capillary format. Due to the unique character of every column the scatter of published C values is wide. The observed C term are higher than those observed with silica monoliths and increase quite linearly with the flow rate. Low-density polymers exhibit better performances than high-density polymers. The majority of HETP versus a plots are drawn from the peak width at half height. Accurate data should be acquired through the second moment of the peak. Some equations for C have been derived. An equivalent dispersion particle diameter is a measure of band broadening in the mesopores. Mass transfer in silica monoliths is well accounted by the theory developed by Guiochon et al.

• 出版日期2006-9-8