2.2. Alcohol Detected by Gas Chromatographic Mass Spectrometry (GC-MS)

The analysis of the alcohol in each 100 µL sample was conducted in an Agilent 5973 mass selective detector, interfaced to an Agilent 6890 gas chromatography with an Agilent 7694 headspace sampler and a HP 5MS column (25m × 0.25mm × 0.25µm), which were all found at HT Labs Inc., San Diego. The flow rate of the carrier gas helium was set at 1 mL/min. A peak in the GC chromatograph with a retention time of 2.39 min was identified as alcohol and this was further confirmed by MS. Peak areas were used for quantitation. A five-point calibration curve covering the alcohol concentration range of 0–2 g/L was constructed. Alcohol-free samples contained a spike with alcohol at a concentration of 0.05, 0.1, 0.5, 1, and 2 g/L and were analyzed in triplicate.