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| Holdtime Studies for Dissolved Gasses in Vapors A gas mixture was made that contained gasses typically of interest in bioremediation monitoring. The gasses in that mixture were carbon dioxide, oxygen, nitrogen, methane, ethane, ethene, hydrogen and an inert gas that was used to reach the desired concentration levels for the other gasses. The concentration levels are shown in Table 1. The mixture was placed into eighteen 20 mL glass vials and the vials were separated into three groups of six. The first group used a plain clean glass vial and butyl crimp top septa, the second also used a plain glass vial and butyl crimp top septa but, after filling the vial with the mixture the vial tops were covered with silicone caulking. The third group used glass vials which were pre-washed with a preserving solution and the closed with the butyl crimp top. Two vials from each group were analyzed with the Microseeps BioRem GC 1. The vials were analyzed on the day they were filled (day 0), the following day (day 1) and a week after they were filled.The analyses showed that, to within instrumental error, the concentrations of each analyte held constant throughout the study, regardless of the vial type. The gas concentrations have been converted to the ground water concentrations that would produce gas concentrations of this magnitude via the bubble strip method (Chapelle, F.H.; McMahon, P.B.; Dubrovsky, N.M. Fujii, R.F.; Oaksford, E.T.; Vroeblesky, D.A. Water Resour. Res. 1995, 31, 359-371.) and the results are shown in Figures 1 and 2. Table 1 Nominal Concentration of Target Analytes
Holdtimes For Bioremediation Indicator Gasses
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