A 3D-printed high-hardness die steel microchip GC column: 3-meter long, low-cost, and exhibiting superior separation performance

In this work, a 3D-printed metal column engineered specifically for micro gas chromatography applications was developed, and an in-depth characterization of its performance and gas separation capabilities were conducted. A microchip gas chromatography column, with dimensions 7.0 × 7.0 × 0.2 cm, was fabricated via Direct Metal Laser Sintering (DMLS) technology using die steel powder. The column incorporates a 3-meter-long circular spiral channel, possessing an internal diameter of 500 μm, and employs OV-1 as the stationary phase. To enable efficient heating, a ceramic plate was affixed to one side of the column. The entire assembly weighs 118 g, facilitating the flexible adjustment of column length in a series configuration, thereby enhancing the analysis of complex mixtures. The column exhibited outstanding separation capabilities across mixtures encompassing ketones, aromatics, alkanes, and alcohols, demonstrating consistent repeatability. Notably, it enabled rapid temperature programming at an impressive rate of 120 °C/min within the boiling point spectrum spanning of C₆ to C₁₈, while maintaining its superior separation performance. This innovative design has achieved remarkable success in separating Benzene Toluene Ethylbenzene & Xylene (BTEX), volatile organic compounds (VOCs), and gasoline, thereby spotlighting its exceptional separation efficiency. Moreover, it offers a viable solution to the prevalent challenges commonly faced by microchip columns, including manufacturing complexity, low repeatability, and high production costs. Significantly, it stands as the longest chromatography column currently employing 3D printing technology for micro gas chromatography and provides significant insights into optimizing column length through the construction of large-curvature channels on a constrained planar substrate.