This study assessed the analysis method for measuring volatile organic silicon compounds (namely as siloxanes) by usinggas chromatography with flame ionization detector. Calibration standard gas was made in a laboratory by using six volatileorganic silicons as model gas. Two different types of working gas were prepared to evaluate quality control in GC-FIDanalysis. Less than 0.2 RSD% of repeatability of retention time was observed in the analysis of calibration standard gas. Inthe linearity test, the highest coefficient of determination (R2) was found to be 0.997 for L2 among volatile organic siliconcompounds. This study demonstrated that quantification of volatile organic silicon compounds can be performed by usingGC-FID analysis with direct injection mode, and the GC calibration can be covered by the gas-phase standard method.

A numerical model is investigated to predict a behavior of the gaseous volatile organic compounds and a subsurface contamination caused by them in the unsaturated zone. Two dimensional advective-dispersion equation caused by a density difference and two dimensional diffusion equation are computed by a finite difference method in the numerical model. A laboratory experiment is also carried out to compare the results of the numerical model. The dimensions of the experimental plume are 1.2m in length, 0.5m in height, and 0.05m in thickness. In comparing the result of 2 methods used in the numerical model with the one of the experiment respectively, the one of the advective-dispersion equation shows better than the one the diffusion equation.