The assay was performed using a Trace 1310 series GC with a TSQ8000 MS detector (Thermo Fisher Scientific, USA). In this study, two columns were used. The in vitro assay products were first processed using a TR-5ms capillary column (30 m × 0.25 mm i.d., 0.25 μm film thickness; Thermo Fisher Scientific, USA). The carrier gas used helium for GC at a flow rate of 1.3 mL min−1. The oven program was as follows: 50 °C for 2 min, linear ramp up at a rate of 10 °C·min−1 to 230 °C, held at 280 °C for 5 min, followed with a linear ramp up at a rate of 10 °C·min−1 to 290 °C, held at 290 °C for 2 min. The injector temperature and transfer line temperature were 250 °C.