Oxaloacetic acid (Standard) is a reference standard for research and analysis in studies involving Oxaloacetic acid. Oxaloacetic acid, also known as oxosuccinic acid or oxalacetic acid, is a four-carbon dicarboxylic acid appearing as an intermediate of the citric acid cycle. In vivo, oxaloacetate (the ionized form of oxaloacetic acid) is formed by the oxidation of L-malate, catalyzed by malate dehydrogenase, and reacts with Acetyl-CoA to form citrate, catalyzed by citrate synthase.(wikipedia) A class of ketodicarboxylic acids derived from oxalic acid. Oxaloacetic acid is an intermediate in the citric acid cycle and is converted to aspartic acidD by a transamination reaction.