A semi-packed micro GC column for separation of the NAFLD exhaled breath VOCs

Abstract

The separation and detection of human breath play a significant role in early and non-invasive disease diagnosis. Various volatile organic compound (VOC) gases are considered as the biomarkers of a nonalcoholic fatty liver disease (NAFLD) patient. In this paper, a micro gas chromatography (GC) column used for VOCs separation of the NAFLD breath sample was presented, from its design, fabrication and separation performance testing. The serpentine column made using microelectromechanical system (MEMS) technology was chosen for its relatively small band broadening. The micro pillar configuration was simulated and optimized. The 3 m and 1 m long column with a cross-section of 200 μm × 240 μm was fabricated by deep-reactive-ion-etching (DRIE) method and sealed with anodic bonding. The stationary phase was coated to the inner wall of the column by static coating. The column was installed into the conventional gas chromatography to test separation performance of the GC. The nonpolar alkane mixture containing the NAFLD biomarker gas pentane was separated and the experimental factors such as the temperature and the carrier gas flow rate were studied. The results indicated that the micro GC column can effectively separate alkanes from C5-C12 within 5 min. This could help the micro detector of micro GC system to quickly identify the contents or concentrations of characteristic alkanes. The micro GC column can meet the requirements of the micro GC system for the breath analysis of the NAFLD or other metabolic liver diseases. The micro column assembled with micro gas detector and preconcentrator can be hopefully developed into a portable breath analysis device.