Application of Polyethylene Glycol Modified Quartz Crystal nanobalance in Conjunction with Principal Component Analysis for Identification of Volatile Organic Compounds

Volatile Organic Compounds (VOCs) are found in everything from paints and coatings to underarm deodorant and cleaning fluids. They are a major concern of the Environmental Protection Agency (EPA). VOCs have been found to be a major contributing factor to ozone, a common air pollutant which has been proven to be a public health hazard. Ethyl acetate vapor present in air is one of the toxic VOCs [1]. Ethyl acetate is an important solvent used in petrochemical and polymer industries. It is commonly emitted from industrial plants and is often a constituent of industrial wastes [2].Quartz crystal nanobalance (QCN) sensors are considered as powerful mass-sensitive sensors to determine materials in the nanogram level. The QCN comprises a thin vibrating AT-cut quartz wafer sandwiched between two metal exciting electrodes. When a small amount of mass is adsorbed at the quartz electrode surface, the frequency of the quartz is changed.Polymer coated quartz crystals have been studied as sensors for various gases [3]. The major drawback of the polymer-modified QCN sensors is a lack of selectivity, since there is no discrimination between the sources of the mass changes. Using pattern recognition techniques is the key of the data processing of the signals of a non-selective sensor. In this regard, the characteristic information contents of the signal have to be recorded. Different chemometric tools such as principal component analysis (PCA) could be applied for this purpose [3-4].This paper reports a method of a thin Polyethylene Glycol-coated QCN sensor for the determination of ethyl acetate in the presence of acetone, ethanol and methyl ethyl ketone as the interfering gases.