Cardiolipin (CL) is an important component of the prokaryotic and eukaryotic inner mitochondrial membrane. In humans, CL is made by cardiolipin synthase from phosphatidylglycerol and cytidinediphosphate-diacylglycerol. Monolysocardiolipin (MCL) is an intermediate in CL remodeling. Acetyl transferase tafazzin mutations impairing linoleic acid transfer to MCL are considered the main reason of Barth syndrome; and autoantibodies to MCL have been found in patients with anti-phospholipid syndrome and lupus. Fluorescent lipids have been used in TLC, electrophoresis, microplatefluorescent assays, and sub-cellular localization experiments.