Substances: Acemetacin (FSQKKOOTNAMONP-UHFFFAOYSA-N) 5-Fluoro Cytosine (XRECTZIEBJDKEO-UHFFFAOYSA-N) Acetochlor-OXA (OTKTUNJJKYTOFF-UHFFFAOYSA-N) 4-Hydroxy-Benzotriazole (NPZTUJOABDZTLV-UHFFFAOYSA-N) Keywords: high resolution mass spectrometry monitoring