Quartz Crystal Nanobalance in Conjunction with Principal Component Analysis for Identification of Volatile Organic Compounds

Quartz crystal nanobalance (QCN) sensors are considered as powerful mass-sensitive sensors to determine materials in the sub-nanogram level. In this study, a singlepiezoelectric quartz crystal nanobalance modified with polystyrene was employed to detectbenzene, toluene, ethylbenzene and xylene (BTEX compounds). The frequency shift of theQCN sensor was found to be linear against the BTEX compound concentrations in the rangeabout 1-45 mg l-1. The correlation coefficients for benzene, toluene, ethylbenzene, andxylene were 0.991, 0.9977, 0.9946 and 0.9971, respectively. The principal componentanalysis was also utilized to process the frequency response data of the single piezoelectriccrystal at different times, considering to the different adsorption-desorption dynamics ofBTEX compounds. Using principal component analysis, it was found that over 90% of thedata variance could still be explained by use of two principal components (PC1 and PC2).Subsequently, the successful identification of benzene and toluene was possible through theprincipal component analysis of the transient responses of the polystyrene modified QCNsensor. The results showed that the polystyrene-modified QCN had favorable identificationand quantification performances for the BTEX compounds.