Research on Micro-VOCs Detecting System Based on multidimensional-GC

In this study, we utilized microelectromechanical system (MEMS) processing technology to design and fabricate a micro gas chromatographic (GC) column. Based on the characteristics of separated volatile organic compounds (VOCs) we selected CB-40 (40% phenyl group + 60% polydimethylsiloxane) to fix the chromatographic column and fabricated a capillary-type micro column as the primary separation column. By selecting the same stationary phase of padding as same as Silica Bond Plot, we fabricated a micro filling chromatographic column as the secondary separation column. Moreover, typical VOC gas mixtures, including hydrogen sulfide, methyl mercaptan, carbon disulfide, dimethyl sulfide, benzene, methylbenzene, ethylbenzene, xylene and styrene, were adopted to be separated and detected, Finally, by designing a combination of sample feeding acquisition modules and control heating modules as well as adopting a self-fabricated micro-channel preconcentrator and a photoionization detector with high sensitivity and small volume, the detection precision was improved considerably. The limit of detection (LOD) of benzene and hydrogen sulfide can reach 50 parts per thousand (ppt).