Potassium phosphate kh2po4

DTPA, EDTA, glutathione (GSH), quercetin, coumarine-3-carboxylic acid (CCA), 7-(diethylamino)coumarin-3-carbohydrazide (CHH), desferrioxamine, ascorbate, potassium phosphate (KH₂PO₄), and multi-compendial grade polysorbate 20 (PS20) and PS80 were from Sigma-Aldrich (Merck KgaA, Darmstadt, Germany). Copper(II) chloride and iron(III) chloride were from Acros Organics (Thermo Fischer Scientifics, Waltham, MA, USA). Ultra-gradient HPLC grade acetonitrile was from J.T. Baker (Avantor Performance Materials, Radnor, PA, USA). Liquid chromatography-MS grade methanol was from Merck KgaA (Darmstadt, Germany). Ultrapure water was from a Millipore Milli-Q water system (Merck KgaA, Darmstadt, Germany). The therapeutic protein solution was provided by Lek d.d. (Mengeš, Slovenia).

All chemicals were of analytical grade or higher and were used as received without any further purification. Deionized water was purified using a Milli-Q system from Millipore (Millipore, USA). HPLC-grade methanol and acetonitrile were purchased from Thermo Fisher Scientific (USA). Standards of UDP-glucose and UDP-galactose were purchased from Merck (Germany). Formic acid (99%, HPLC-grade) and ammonium formate (99%, LC-MS grade) were purchased from Merck (Germany). Potassium phosphate (KH₂PO₄) was purchased from Sigma. Sample vials, vial inlets, and vial snap caps were purchased from Merck (Germany). The HSS T3 column (2.1 × 100 mm, 1.8 μm) and BEH amide column (2.1 × 100 mm, 1.7 μm) were both obtained from Waters (UK).

Polyethylene glycol (PEG) with molar masses of 1000, 3000, 4000, and 10,000 g/mol were purchased from Sigma-Aldrich (Seoul, Republic of Korea). The salts, sodium citrate (Na₃C₆H₅O₇), ammonium sulfate [(NH₄)₂SO₄], potassium phosphate (KH₂PO₄), and sodium chloride (NaCl), were also purchased from Sigma-Aldrich. Tryptic soy, potato dextrose, and mannitol-yolk-polymyxin B broths were purchased from BD Difco (Franklin Lakes, NJ, USA). The bicinchoninic acid (BCA) protein assay kit was supplied by Thermo Fisher Scientific (Pierce, #23227; Waltham, MA, USA). All chemicals used in this study were of analytical grade.