Activated carbon-coated particles as adsorbent for packed columns in gas chromatography

This study reports the first development of gas chromatographic columns packed with activated carbon (AC)-coated adsorbent particles. The AC-coated adsorbent particles were prepared by coating an AC layer on solid support particles using a vacuum carbon coater. Glass beads, diatomite, a porous polymer, and activated alumina particles were investigated as the support materials. The AC layer was uniformly coated on the surface of each support material, achieving a thickness of approximately 300-400 nm after 500 coating cycles. The AC-coated particles were packed in a stainless steel tube with an inner diameter of 1.0 mm and a length of 1.0 m to prepare a packed capillary column. The retention performance of the AC-coated particle-packed columns was evaluated using a capillary gas chromatograph coupled with a flame ionization detector. Strong retention for typical low-molecular-weight organic compounds, including methane, ethane, and propane, was observed. The retention power increased with increasing number of AC-coating cycles and support surface area. The theoretical plate numbers were lower for adsorbents coated on nonporous and low-porous supports, and higher for supports with a large specific surface area. The results demonstrated that the present AC-coating method readily affords AC adsorbents with high retention for typical volatile compounds.