Accordingly, 1,2-dichlorobenzene as an internal standard (1 mL of a solution in methanol, 130 ng mL1 ) was injected into GC–MS simultaneously with the samples. Carrier gas was helium at 21 psi, and the mass spectrometer scanned from m/z 29 to m/z 400 at a scanning rate of 2.05 scans s1
(Srisajjalertwaja et al., 2012).
.