Instrumentation and Conditions. Analysis was per-formed on an Agilent 6890N gas chromatograph (GC) cou-pled with an Agilent 5975B mass spectrometer (MS, Agilent
Technologies,Wilmington, DE, USA). Samples were injected
using an Agilent autosampler unit.
The capillary column used was a HP-1MS [30m×
0.25mm, 0.25