Figure 2.

LC–MS (atmospheric-pressure chemical ionization, APCI+) spectral changes during the oxidation of the selenoxide form of selenide 6 in H₂O at 25 °C. For a‒c, H₂O (100%) was used as an eluent for the LC under a continuous flow at 0.3 mL/min, and 3 μL of the sample solution was injected into the LC and analyzed by the APCI+ mode. Reaction conditions: (a) Selenide 6 (0.038 mmol) and H₂O₂ (0.038 mmol) were mixed in H₂O (800 μL); (b) to a was added H₂O₂ (0.15 mmol); (c): to b was added HCl (0.15 mmol).