2.6. TC and D-TCF Analysis by LC-MS/MS

The FMN photolytic reaction on TC degradation was analyzed using an LC-MS/MS method. The separation of TC and FMN in the solutions is described in Section 2.3. The samples were maintained under blue light irradiation at 20 W/m² for 1 h. TC, FMN, and D-TCF were eluted by an Agilent Poroshell 120 EC-C18 column (2.7 µm, 4.6 mm × 150 mm, Agilent Technologies, Palo Alto, CA, USA), followed by LC-MS/MS analysis. Using an Agilent 1200 Series HPLC System, an electrospray ionization (ESI) source was connected to an Agilent 6410B triple quadrupole MS in this study.

The mobile phase was composed of 0.1% methanoic acid (A) and methanol (B). The process of separation was completed by a mobile phase, the profile of which is depicted below. The linear gradient started with 0–2 min, 95%–80% A; 2–8 min, 80% A; 8–12 min, 80%–40% A; 12–15 min, 40% A; 15–19 min, 40%–5% A; 19–24 min, 5% A; and 24–27 min, 5%–95% A. The final mobile phase was set at 95% solvent A from 27 to 30 min. The reaction solution at a volume of 10 μL was injected at a flow rate of 0.4 mL per minute. TC or D-TCF was investigated by a positive-ion mode for charged fragments. The data were obtained and inspected using the MassHunter Workstation software, version B.06.00.