Trace gas VOC detection using metal-organic frameworks as pre-concentrators and semiconductor gas sensors

A method for the measurement of low gas concentrations is presented. The method was developed for detection of Volatile Organic Compounds (VOCs) in indoor air quality applications and tested with benzene, a carcinogenic VOC with no safe exposure limit value. Using metal organic framework materials, gas pre-concentration devices for benzene were prepared on ceramic micro hotplates and characterized. Two MOF materials (HKUST-1 and MIL-53) were tested. Both showed good preconcentrator performance concerning adsorption and desorption of the target gas. A significant temporary decrease of the benzene concentration in the sampling phase and a corresponding increase in the desorption phase were detected using a mass spectrometer. The MOF pre-concentrators were also tested in combination with a semiconductor gas sensor resulting in a significant increase in the sensor response in the desorption phase.