Semi-Packed Gas Chromatography Columns With Density Modulated Pillars

The separation column is the most important component which influences the performance of gas chromatography systems. Among a number of column designs, the microfabricated semi-packed column has attracted particular attention in micro gas chromatography because it enhances the separation efficiency and provides higher sample capacity compared to the open-channel counterparts. However, these added advantages come at the cost of higher pressure drops per unit length of the separation column. This paper reports new semi-packed column designs through density modulation of the pillars by changing the spacing between rows or the number of pillars per row from. Various geometries were fabricated and tested against regular semi-packed columns having either one pillar or four pillars per row. Different performance metrics were measured including column pressure drop, optimal flow velocity, number of theoretical plates, and separation efficiency. The density-modulated semi-packed columns provide efficiencies comparable with that of semi-packed columns embedding more pillars per row while requiring a lower inlet pressure which is more comparable with the columns embedding one pillar per row. These density-modulated columns were able to successfully separate diesel and kerosene compounds and to identify the major hydrocarbon constituents of these two widely used samples.