2.3. Analysis of Remaining Phthalates in Experimental Samples

For liquid samples, 0.5 mL of the sample (reaction mixture) was mixed with 0.5 mL of hexane. For bioreactor experiments, 0.5 g of SMC fragments was mixed with 0.5 mL hexane. The mixture was vortexed for 10 s and centrifuged at 12,000× g for 10 min. The organic phase was collected and filtered using 0.22 μm filters and applied to GC analysis. Samples were analyzed by gas chromatography with a flame ionization detector, GC-FID (Hewlett-Packard, Palo Alto, California, CA, USA) and a J&W DB-1701 GC column (Agilent Technologies, Santa Clara, California, CA, USA). The initial column temperature was set at 45 °C; the temperature increased by 10 °C/min to 260 °C and then increased by 2.5 °C/min to 340 °C. Injector and detector temperatures were set at 270 and 290 °C, respectively. Nitrogen was used as both a carrier gas (flow rate 5.0 mL/min) and a makeup gas (flow rate 20.0 mL/min). The recovery percentages for BBP, DBP, DCP, DEP, and DEHP were 97.1, 98.4, 93.3, 96.3, and 94.9%, respectively. The remaining percentages of phthalates were calculated using the formula: [%] = (residue phthalate concentration/initial phthalate concentration) × 100.