Application Chelating reagent used in a sensitive (μM) assay for vanadium.1 Biochem/physiol Actions Selective inhibitor of catechol O-methyl transferase (COMT); penetrates the blood brain barrier and is useful both orally and parenteraly in experiments where inhibition of COMT in the central nervous system is required. Caution Photosensitive Quality Solutions may be stored for several days at 4 °C.