GC and GC/MS analysis
The liquid CO2 flower extract and liquid CO2 fractions of concrete
were analyzed by GC and GC/MS. GC analysis was carried
out on a Shimadzu GC-17A Gas Chromatograph equipped with an
FID and 25m×0.25mm×0.25 m WCOT column coated with 5%
diphenyl dimethyl siloxane supplied by J & W (DB-5). Helium was
used as carrier gas at a flow rate of 1.2 mL/min at a column pressure
of 42 kPa. Samples (0.2 L) were injected into the column with
a split ratio of 50:1. Component separation was achieved following
a linear temperature program of 60–200 ◦C at 2◦C/min and then
held at 200 ◦C for 60 min, with a total run time of 130 min. The
percentage composition was calculated using peak normalization
method assuming equal detector response. The samples were then
analyzed on a Shimadzu QP 5000 GC/MS fitted with the same column
and following the same temperature program as above. The
MS parameters are as follows: ionisation voltage (EI) 70 eV, peak
width 2 s,mass range 40–400amu and detector voltage 1.5 V. Peak
identification was carried out by comparison of the mass spectra
with mass spectra available on database of NIST-1, NIST-2, Adams
and Wiley libraries. The compound identification was finally confirmed
by comparison of their relative retention indices with the
literature values [11,12].