Variables: dissolved_organic_carbon Keywords: high resolution mass spectrometry Substances: 18-beta-Glycyrrhetinic acid (MPDGHEJMBKOTSU-YKLVYJNSSA-N) 5-Fluoro Cytosine (XRECTZIEBJDKEO-UHFFFAOYSA-N) 3-5-Diiodo-L-tyrosine (NYPYHUZRZVSYKL-ZETCQYMHSA-N)