Oxygen content of the headspacewas measured by Agilent 6890
gas chromatograph equipped with a HP-MOLESIEVE column
(30 m 0.53 mm i.d. 0.25 mm) and a thermal conductivity detector
(TCD). The injector was kept at 150 C, while the oven temperature
was adjusted to 60 C. The injector was in splitless mode
and nitrogen was used as carrier gas.
For the carbon dioxide measurements, Shimadzu GC-2010 gas
chromatograph equipped with a TCD and HP-PlotQ column
(30 m 0.53 i.d. 0.25 mm) was used. The temperature of the
injector and oven were 200 C and 90 C, respectively. Samples of
50 mL were injected via a split injection port at a split ratio of 0.5:1.
Carrier gas was nitrogen at a flow rate of 63.8 mL/min.