Micromachining technology for the miniaturization of gas-chromatographic (GC) components together with innovative pre-concentration materials are used for the development of a portable sub-ppb level monitoring system for aromatic volatile organic compounds (VOC). The high sensitivity of metal oxide semiconductor (MOX) gas sensors is combined with GC techniques to increase selectivity and reduce the detection limit. The systemic approach includes the study of innovative pre-concentration materials, micromachining of GC components and devices, the fabrication and characterization of complete system prototypes as well as the development of application-specific control electronics.