Abstract
Gas chromatography (GC) is the chemical analysis technique most widely used to separate and identify gas components, and it has been extensively applied in various gas analysis fields such as non-invasive medical diagnoses, indoor air quality monitoring, and outdoor environmental monitoring. Micro-electro-mechanical systems (MEMS)-based GC columns are essential for miniaturizing an integrated gas analysis system (Micro GC system). This study reports an open-tubular-type micro GC (μ-GC) column with internal bump structures (bump structure μ-GC column) that substantially increase the interaction between the gas mixture and a stationary phase. The developed bump structure μ-GC column, which was fabricated on a 2 cm × 2 cm μ-GC chip and coated with a non-polar stationary phase, is 1.5 m-long, 150 μm-wide, and 400 μm-deep. It has an internal microfluidic channel in which the bumps, which are 150 μm diameter half-circles, are alternatingly disposed to face each other on the surface of the microchannel. The fabricated bump structure μ-GC column yielded a height-equivalent-to-a-theoretical-plate (HETP) of 0.009 cm (11,110 plates/m) at an optimal carrier gas velocity of 17 cm/s. The mechanically robust bump structure μ-GC column proposed in this study achieved higher separation efficiency than a commercially available GC column and a typical μ-GC column with internal post structures classified as a semi-packed-type column. The experimental results demonstrate that the developed bump structure μ-GC column can separate a gas mixture completely, with excellent separation resolution for formaldehyde, benzene, toluene, ethylbenzene, and xylene mixture, under programmed operating temperatures.
Highlights
The analysis of volatile organic compounds (VOCs) is fundamental in a wide range of applications, including public safety management, non-invasive medical diagnoses, indoor air quality monitoring, and outdoor environmental monitoring [1,2,3,4,5,6,7,8,9]
The mechanically robust bump structure μ-gas chromatography (GC) column proposed in this study achieved higher separation efficiency than a commercially available GC column and a typical μ-GC column with internal post structures classified as a semi-packed-type column
This study reports a mechanically robust bump structure μ-GC column with a comparable separation performance
Summary
The analysis of volatile organic compounds (VOCs) is fundamental in a wide range of applications, including public safety management, non-invasive medical diagnoses, indoor air quality monitoring, and outdoor environmental monitoring [1,2,3,4,5,6,7,8,9]. VOCs can be collectively detected by various gas sensors and detectors, these devices typically lack the selectivity to discriminate between constituents of complex mixtures. Simple gas compounds can be analyzed by high-performance mass spectrometry and infrared spectroscopy systems, whereas complex mixtures typically require a gas chromatography (GC) system [10,11,12]. GC techniques are beneficial and reliable in the analysis of complicated mixture gases in the aforementioned applications. Such analyses are usually performed with commercial bench-top instruments such as a gas chromatography–mass spectrometer or a gas chromatograph equipped with a flame ionization detector (FID) [13,14]. A GC system that consists primarily of a preconcentrator and separation column is required to improve the sensitivity and selectivity of the detector, and such systems are used for the determination of the discrete components
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