Substances: 5-Methylpyridine-3-carboxylic-acid (DJDHHXDFKSLEQY-UHFFFAOYSA-N) 4-Hydroxy Diclofenac (KGVXVPRLBMWZLG-UHFFFAOYSA-N) 1-Naphthylacetic acid (PRPINYUDVPFIRX-UHFFFAOYSA-N) 2-Aminobenzimidazole (JWYUFVNJZUSCSM-UHFFFAOYSA-N) Keywords: monitoring high resolution mass spectrometry