Shunta Futagami - Speaker

Takeshi Hara - Contributor

Prof. Dr. Ir. Heidi Ottevaere - Contributor

Herman Terryn - Contributor

Gino Baron - Contributor

Gert Desmet - Contributor

Wim De Malsche - Contributor

Introduction: Vast progress in the column efficiency of pillar array columns has been achieved with the adoption of radially elongated pillars (REPs) as an alternative to classical cylindrical pillars, and this pillar shape can provide a sub-micron minimum plate height. We recently reported that the mesoporous-silica layer prepared in a REP column by sol-gel processing dramatically increases the retention capacity while keeping its high column efficiency. In this contribution, a REP column with a thicker mesoporous-silica layer is reported and its performance is compared with a mesoporous-silica layered REP column prepared with the previously reported recipe in both isocratic mode and gradient mode. Experimental: Mesoporous-silica layer was prepared in a REP column (1 mm wide, 18 μm deep, and 16.5 cm long) with a sol-gel feed solution, which consisted of a mixture of tetramethoxysilane (TMOS) and methyltrimethoxysilane (MTMS), polyethylene glycol (PEG), urea, and acetic acid aqueous solution. In order to prepare a thicker layer than the one previously reported, the amount of the TMOS/MTMS mixture in the feed was approximately 30% increased. After the C18-modification, the chromatographic performance of the REP column was tested with a nano LC system. Scanning electron microscopy (SEM) was applied to visually inspect the mesoporous silica layer. Results & Discussion: SEM images of a prepared REP column showed a straight and uniform deposition of the mesoporous-silica layer. From the SEM images, the thickness of the layer was determined to be 220 nm. This is 1.2 times larger value than the layer prepared by the previously reported condition (180 nm). Isocratic separations of a mixture containing thiourea and 7 alkylphenones revealed that the thicker layer column has a 1.3 times larger retention capacity than the thinner layer column. Even though the tailing derived from extra-column band broadening reduces the performance of both the thicker layer column and the thinner layer column, both columns gave similar H-u curves and the minimum plate heights of 1.4 μm (for thinner one) and 1.6 μm (for thicker one) were observed for a retained component. Gradient separations of the aforementioned mixture were carried out to demonstrate the performance in more practically relevant conditions. Due to the higher retention capacity and the similar column efficiency, the thicker layer column gave a larger maximum conditional peak capacity of 253, while the thinner layer column gave 228 in the same gradient condition.
26 Sep 2018

Event (Conference)

Title32nd International Symposium on Chromatography (ISC 2018)
Abbrev. TitleISC 2018
Web address (URL)
Degree of recognitionInternational event

ID: 39952887