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• A semi-packed column with high-density elliptic cylindrical posts was developed. • The surface area of SC HECP is 71% larger than SC CP. • The aspect ratio of SC HECP is 76% larger than SC CP. • Higher surface area and aspect ratio leads to better performance. Semi-packed columns are microfabricated gas chromatography columns which have a large surface area and high aspect ratio. In this paper, a new semi-packed column with high-density elliptic cylindrical posts (SC HECP) made by a micro-electro-mechanical system (MEMS) technique was reported. Compared to a semi-packed column with cylindrical posts (SC CP) under the same effective width, the surface area and aspect ratio of SC HECP were improved by 71.19% and 76.47%, respectively. To compare the performance of these two semi-packed columns, SC HECP and SC CP were fabricated. A 10-nm thick alumina film was deposited as the stationary phase by atomic layer deposition technique to ensure the uniformity and repeatability of the stationary-phase film. A contrast experiment was conducted, and the results showed that compared with SC CP, better separation performance was realized in SC HECP due to the increase in surface area and aspect ratio. The number of theoretical plates of nonane was increased by 541.84%, and the tailing factor was decreased by 54.31%. [ABSTRACT FROM AUTHOR]

The micro gas chromatography column (μGCC) is one of the key components of the miniaturized gas chromatography system. However, light alkanes are difficult to be separated by a micro gas chromatography column, especially for methane and ethane, because the length of μGCC is limited by the area of a silicon substrate. More importantly, the heterogeneous microchannel surface formed by silicon glass bonding causes uneven stationary phase coating and the forces between the untreated microchannel surfaces and the stationary phase materials are weak, which will prevent the improvement of separation performance. In this paper, a micro gas chromatography column (μGCC) with uniform HKUST-1 stationary phase is reported. Significantly, an alumina film prepared by the atomic layer deposition (ALD) technique is used to homogenize the heterogeneous microchannels. The alumina is a hydrophilic material and the alumina made by the ALD technique is uniform. The forces between hydrophilic alumina film and HKUST-1 are strong, which can greatly improve the coating uniformity of the hydrophilic stationary phase HKUST-1. The test results show that the μGCC could baseline separate the light alkane mixtures (CH 4 , C 2 H 6 , C 3 H 8 , and C 4 H 10) at the high testing temperature of 120 °C. The maximum resolution of the difficult-separated methane and ethane reached 19.2, which is 108 % higher than the μGCC using the same stationary phase without homogenizing the microchannel inner surface. The μGCC uses ALD alumina film to homogenize the microchannel inner surface; meanwhile, hydrophilic ALD alumina has a strong electrostatic attraction with the hydrophilic stationary phase HKUST-1. Homogeneous microchannel surface and strong electrostatic attraction are favorable to obtain uniform stationary phase which greatly improves the separation performance, resulting in a large resolution for methane and ethane. The μGCC has broad application prospects in light alkane separation. [Display omitted] • A novel μGCC with a homogeneous microchannel. • The uniform distribution of the HKUST-1 stationary phase is obtained. • Baseline separation of light alkanes (C1–C4) at 120 °C is obtained. • The resolution of methane and ethane can reach 19.2. [ABSTRACT FROM AUTHOR]