A 3D-printed metal column for micro gas chromatography

• Published in: Lab on a chip 2020-09, Vol.2 (18), p.3435-3444
• Main Authors: Phyo, Sooyeol, Choi, Sung, Jang, Jaeheok, Choi, Sun, Lee, Jiwon
• Format: Article
• Language: English
• Subjects: Alcohols; Alkanes; Bleeding; Chromatography; Column chromatography; Gas chromatography; Gas mixtures; Gas separation; Heat distribution; High temperature; Ketones; Microchannels; Porosity; Pretreatment; Substrates; Thermodynamic properties; Three dimensional printing; Titanium base alloys; X ray microscopy
• ISSN: 1473-0197; 1473-0189
• DOI: 10.1039/d0lc00540a

In this work, a 3D-printed metal column was developed for micro gas chromatography (GC) applications and its properties and gas separation performances were characterized. By using a Ti6Al4V grade 23 powder, a square spiral one meter-long column (3D-column) was 3D-printed on a planar substrate of 3.4 × 3.3 × 0.2 cm and then perhydropolysilazane (PHPS) was deposited as a pre-treatment agent, followed by a coating of stationary phase (OV-1) onto the inner wall of the micro-channel. The 500 μm-diameter circular channel and two 800 μm-wide ports of the 3D-column were confirmed to be uniform by 3D X-ray microscopy without any distortion. The physical and thermal properties of the 3D-column were found to be very similar to that of the standard Ti6Al4V grade 23 alloy with near zero porosity (∼0.07%). The 3D-column with pre-treatment and stationary coating demonstrated efficient separation performance of gas mixtures containing alkanes, aromatics, alcohols, and ketones compared to a bare or only pretreated 3D-column in terms of the peak shape, broadening, and resolution ( R > 1) within 2-3 min. The well-matched thermal responses to the target temperatures were demonstrated at the ramping rates of 10-20 °C min −1 upto 200 °C with uniform heat distribution over the 3D-column. In addition, the column bleed profiles showed that the 3D-column with PHPS had a 71% lower baseline intensity at 350 °C than that without PHPS. The 3D-column was then employed to separate a gas mixture of twelve alkanes (C9-C18, C22, C24) without any significant column bleeding and peak tailing. Therefore, the thermal responses and stability of the 3D-column promise its applicability in high temperature GC applications. A square spiral 1 m-long column for gas mixture separation was 3D-printed out with the dimensions of 3.4 × 3.3 × 0.2, followed by pre-treatment and stationary phase coating.