APPLICATION OF HEADSPACE ANALYSIS FOR THE DETERMINATION OF VOLATILE ORGANIC-COMPOUNDS IN CONTAMINATED SOILS

It has been shown that headspace analysis is more reliable than the purge-and-trap method for the quantification of volatile organic compounds (VOCs) in soil samples. The major shortcoming of the headspace analysis in the case of soil samples is the inability of water to fully extract the soil contaminants. Experiments were conducted to fully understand the limitations and applicability of headspace analysis for the quantification of VOCs in field contaminated soils. A set of experiments were conducted using soil samples amended with (i) trichloroethylene, (ii) toluene, and (iii) trichloroethylene and toluene. A second set of experiments were conducted using field soil samples contaminated with toluene. The batch equilibrium experiments showed that the limitation of the headspace analysis for soil samples lies in the incomplete desorption of the contaminants in soil/water mixtures. However, the addition of methanol appears to overcome this problem. The toluene Henry's law constant increased with an increase in the methanol content of the soil slurries. Therefore, the Henry's law constants of VOCs in methanol need to be determined for the successful application of headspace analysis in the case of soil samples.