Development of Open-Tubular-Type Micro Gas Chromatography Column with Bump Structures

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.

Metal–organic framework-based high-performance column chip for micro gas chromatography: hybrid function for simultaneous preconcentration and separation of volatile organic compounds

“…2b). 28 The bump structure on the column channel surface was alternately placed to confront each other at 150 μm intervals. The hybrid GC chip had a column length of 1.5 m, a channel width of 150 μm, and a channel depth of 400 μm.…”

“…1, μ-PCs have been developed for miniaturization of the conventional TD system for gas preconcentration, and μ-GCs have been developed for replacing with conventional GC system for gas separation. 10,[23][24][25][26][27][28] These two MEMS-based devices have become key elements in development and fabrication of compact GC systems because, unlike traditional TD tubes or GC columns, these MEMS based devices can be operated without any external heating equipment such as TD equipment and oven equipment (Fig. 1b).…”

Review on micro-gas chromatography system for analysis of multiple low-concentration volatile organic compounds: preconcentration, separation, detection, integration, and challenges

“…Recently, capillary GC columns coated with a thin stationary phase, which mainly comprise polydimethylsiloxane (PDMS) and are easily modified using various functional groups, have been widely used owing to the disadvantages of packedtype columns with low separation efficiency owing to diffusion in the stationary phase, low plate number (representative performance index of the column), and high pressure. Figure 2b shows the µ-GC device that replaces the GC system, which comprises an oven and a packed/ capillary GC column [33][34][35][36]. A capillary GC column is a thin, long fused silica tube with an inner diameter range of 0.1-0.53 mm and a length range of 15-60 m. Apart from the stationary phase, the length of the column has the greatest impact on separation performance.…”

Real-time detection of isoprene marker gas based on micro-integrated chromatography system with GOQDs-modified μGC column and metal oxide gas detector

“…Conventional gas analysis chromatography workstations have the disadvantages of being bulky, complex, expensive and difficult to operate, and are not suitable for rapid screening of chronic diseases on a large scale. And with the rapid development of micro-electromechanical system (MEMS) technology and nanomaterials technology, many scholars have developed microstructured chromatography chips [15,[20][21][22][23] and gas-sensitive sensors [24][25][26][27][28][29] for various applications. They offered both high performance and high integration for applications in portable instrumentation.…”