Anthracene-9-carboxylic acid-d 9 is the deuterium labeled Anthracene-9-carboxylic acid. Anthracene-9-carboxylic acid (9-Anthracenecarboxylic acid) is an anthracene derivative traditionally used to block and identify Ca2+-activated Cl- currents (CaCCs) in various cell types, like diverse smooth muscle cells, epithelial cells and salivary gland cells.