Chromafil xtra pet

Degradation experiments were performed in a 1 L undivided laboratory-scale electrochemical cell (Redox.me, Sweden), where the anodes described in Section 3.2 were used to carry out the oxidation reactions. The counter electrode was a commercial stainless steel 317 L electrode with dimensions of 40 × 80 × 2 mm³, and the reference electrode selected was Ag/AgCl (+0.210 V vs. SHE), placed in the vicinity of the working electrode (Redox.me, Sweden). The interelectrode distance was fixed at 40 mm. Chronopotentiometry experiments were conducted with a potentiostat/galvanostat AUT302N.S PGSTAT302N acquired from Metrohm (Belgium), including a pH/temperature module (pX1000.S). At given time intervals, 1 mL samples were collected, filtered with a high-grade syringe filter (CHROMAFIL® Xtra PET, 25 mm diameter, 0.2 μm pore size, Macherey-Nagel, Germany) and subsequently quenched with 500 μL UHPLC-grade methanol to prevent further degradation reactions. Experiments were conducted in batch mode, at room temperature, and with constant magnetic stirring at 600 rpm. To ensure the reproducibility and reliability of the results, target experiments were performed at least in triplicate, and complementary tests were conducted at least in duplicate.

Subsamples (40 ml) for the analysis of DOC were sterile filtered (Filtropur S) after sampling and stored at −20°C. They were thawed before analysis with an ion chromatography system on an Elementar vario TOC cube (working range, 0.1 to 50 mg × liter⁻¹; Elementar Analysensysteme, Langenselbold, Germany). Sample measurements were performed in duplicate using a sample volume of 10 ml. Subsamples (40 ml) for the analysis of inorganic nutrients (nitrate, nitrite, ammonium, and phosphate) were directly stored at −20°C after sampling. They were thawed and filtered through 0.45-µm filters (Chromafil Xtra PET; Macherey-Nagel GmbH & Co. KG) before analysis using flow injection on a Quikchem QC 8500S2 instrument (Lachat Instruments, Loveland, CO).