A Quartz Crystal Resonator Modified with a Metal-Organic Framework for Sensing of Benzene, Ethylbenzene, Toluene and Xylenes in Water

This work describes the use of a quartz crystal microbalance (QCM) based sensor for gravimetric sensing of benzene, toluene, ethylbenzene, and xylenes (BTEX). A film of a Cu-based metal-organic framework (MOF) capable of BTEX adsorption is deposited on the gold electrode of a quartz resonator (10 MHz). The sensor is operated under constant flow of water, simultaneously measuring frequency shifts in multiple harmonics. Introduction of BTEX compounds in the water shifts the frequency, enabling detection. Analysis of deviation in the 3
^rd
and 5
^th
harmonics enables discrimination of response from either of the BTEX molecules. The response time further enables understanding of diffusion kinetics of each molecule into the framework.