2.5. Analysis of transesterification reactions by immobilized LipM7-PhaP
PHB nanofibers containing immobilized LipM7-PhaP (100 mg) were added to a 10 mL solution of 1 M octanoic acid and 1 M MeOH. The reaction mixture was incubated at 30°C under constant orbital shaking at 250 rpm. Samples (100 µL) were withdrawn every 12 h until the reaction reached equilibrium. Withdrawn samples were mixed with 900 µL of chloroform containing n-hexane as an internal standard. Synthesized methyl octanoate, and residual octanoic acid and methanol were analyzed by gas chromatography on an HP-5 capillary column (30 m × 0.32 mm × 0.25 µm, J&W Scientific; Agilent, Santa Clara, CA) equipped with a flame ionization detector (FID). Helium was used as the carrier gas at a flow rate of 1.3 mL/min. The temperatures of the injector and detector were set at 250°C and 340°C, respectively. Starting from 100°C, the oven temperature was sequentially raised to 260°C (15°C/min) and 315°C (5°C/min), and held at this temperature for 15 min. Samples (1 µL) were injected in the split mode.