Experimental Study of Biodegradation of Ethanol and Toluene Vapors

Gas phase samples of toluene were collected from glass samplers placed in the
flow lines (see Figure 3-1). 0.1 mL samples were taken from these samplers using a
one mL gas-tight syringe and then injected into the GC. Air phase calibration standards
for toluene concentrations were prepared by adding an amount of liquid toluene in the
range of 10 to 60 μL into 160 mL, sealed serum bottles containing 55 mL of water at 25
ºC. Using the known Henry’s constant and volumes of the gas and water phases in the
bottles, the toluene concentrations in the gas phase could be calculated (Gossett, 1987;
Cesario et al., 1997). The calibration curve is given in Appendix B (See Figure B-7).
Reproducibility studies using calibration standards demonstrated that GC measurements
for both liquid and gas toluene concentrations were repeatable to ± 8 %. Gas phase
concentrations of ethanol were determined by passing the gas stream through a known
amount of water (500 mL) in a flask for a measured interval of time (1hr), and then the
liquid samples were analyzed using the GC. Similar reproducibility of measurement
was achieved as that for toluene samples.
3.3.3 GC-MS Analysis
To identify and determine the molecular weight of metabolite byproducts
recovered in the bioremediation experiments, the liquid samples were filtered through a
nylon membrane with 0.2 μm openings. The filtered samples were analyzed using a
GC-MS (Model VG70VSE, VG Analytical) at the Department of Chemistry, University
of Saskatchewan.
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