Initiator microwave system

Approximately 0.5 g of PC pellets were charged into a high-pressure vial along with 10 ml of the KMH solution. The vials were closed with hermetically sealed metallic lids and placed into a microwave reactor (Initiator+ Microwave System, Biotage, Sweden). The reaction time was taken to start when the system reached 5 °C below the programmed temperature (several reaction temperatures were studied). The system was stirred magnetically at 600 rpm. After the reaction time, 10 ml of distilled water was added. The insoluble unreacted PC was filtered off, washed with methanol (50 ml) and distilled water (200 ml), dried under vacuum at 80 °C, and weighed. The filtered solution had a reddish color and was neutralized with concentrated hydrochloric acid. Acid addition was stopped at approximately pH 4 (the depolymerization product serves as acid/base indicator, since the solution goes from reddish to colorless). The homogeneous neutralized solution was placed on a rotary evaporator and a single distillation step was applied; 200 mBar at 50 °C. Upon full evaporation of methanol, BPA monomer precipitated out. The flask containing the white solid was left for 1h at room temperature, allowing crystallization of BPA, which was subsequently filtered, washed with distilled water (3x), dried under vacuum, and weighed.

Aliquots of 200 μL of 200 μM non-illuminated and illuminated α-LA samples were hydrolyzed in a Biotage Initiator+ microwave system (Biotage, Uppsala, Sweden) using 300 μL of 8 M methanesulfonic acid (MSA) containing 0.2 % (w/v) tryptamine and 100 μL of MilliQ water in 2 mL microwave reaction vials (resulting in a final concentration of MSA of 4 M). Following hydrolysis, the samples were subjected to amino acid analysis by UHPLC according to the method described by Zainudin et al. 39

In a typical experiment (with exemptions specified where occurring), 0.5 g of PET pellets were charged into a high-pressure vial with 10 ml of a 1.25 M KOH solution in methanol (from now on referred to as KMH solution). The vials were closed with hermetically sealed metallic lids and placed into a microwave reactor (Initiator+ Microwave System, Biotage, Sweden). The microwaves reactor takes typically 45 to 60 s to reach the desired temperature. Furthermore, it keeps the system temperature at ±5 °C of the programmed value, reason for which, the reaction time was taken to start when the system reached 5 °C below the programmed temperature (several reaction temperatures were studied). The system was stirred magnetically at 600 rpm.
After the specified reaction time, 10 ml of distilled water was added. The insoluble unreacted PET was filtered off, washed with distilled water (200 ml), dried under vacuum at 80 °C, and weighed. The filtered solution was neutralized with concentrated hydrochloric acid, producing a white precipitate. Acid addition was stopped around pH 4. The white solid was filtered off, washed with distilled water (200 ml) and methanol (100 mL), dried under vacuum, and weighed.