3.1. Chemicals
POLAND, ALDRICH
Methanol, acetonitrile (LC gradient grade and LC-MS grade), water (LC-MS grade), DMSO, 98–100% formic acid, methylglyoxal (MGO, 40% in water), and bovine serum albumin (BSA) were purchased from Merck–Sigma–Aldrich (Poland–Sigma-Aldrich, Poznań, Poland). Glacial acetic acid, NaCl, KCl, Na