Recognition and quantification of perchloroethylene, trichloroethylene, vinyl chloride, and three isomers of dichloroethylene using acoustic wave sensor array

Recognition and quantification of six closely related chlorinated organic vapors at low part-per-million concentrations have been demonstrated for the first time with an array of four acoustic wave chemical sensors. The analyzed vapors include perchloroethylene (PCE); trichloroethylene (TCE); vinyl chloride (VC); and three isomers of dichloroethylene (DCE), cis-1,2-DCE, trans-1,2-DCE, and 1,1-DCE, all at concentrations from 0 to 100 ppm. The developed sensor array system can detect as little as 0.2 ppm of PCE, 0.8 ppm of TCE, 1.4 ppm of cis-1,2-DCE, 1.4 ppm of trans-1,2-DCE, 3 ppm of 1,1-DCE, and 3.5 ppm of VC. Quantification of TCE and cis-1,2-DCE vapor mixtures was achieved using multivariate calibration techniques. The locally weighted regression (LWR) analysis provides more accurate results over the partial least squares (PLS) regression. The errors in concentration prediction using LWR analysis were 2.6 ppm and 3.1 ppm for TCE and cis-1,2-DCE, respectively.