Detection of volatile organic compounds in aqueous solutions by phthalocyanine coated quartz crystal microbalance

The surface of the quartz crystal microbalance was coated with using soluble three phthalocyanine coating materials for detection of a variety of volatile organic compounds such as ethanol, 2-propanol, etc. in aqueous solutions. The changes of the physico-chemical properties of phthalocyanine thin films were observed by the variation of sensitivity of the coated quartz crystal microbalance with detection media. The fundamental determination mechanism was based on the shifts in resonance frequency of the quartz crystal due to adsorption of volatile organic compounds on the coated surface of the sensor. The pi-pi or hydrogen bonding interaction were proposed as interaction mechanism to explain the sensor response during the adsorption. A two-step adsorption model for non-linear response curves and Henry's Law for linear response curves were used to describe for the adsorption mechanism. The free adsorption energies of the specific interactions from the adsorption isotherm model were also evaluated.