Substances: 18-beta-Glycyrrhetinic acid (MPDGHEJMBKOTSU-YKLVYJNSSA-N) 1-Hydroxy-Benzotriazole (ASOKPJOREAFHNY-UHFFFAOYSA-N) 3-5-Diiodo-L-tyrosine (NYPYHUZRZVSYKL-ZETCQYMHSA-N) 2 -2 -Difluorodeoxyuridin (FIRDBEQIJQERSE-QPPQHZFASA-N) Keywords: high resolution mass spectrometry monitoring