Thiobarbituric acid
Thiobarbituric acid is an organic compound and a heterocycle. It is used as a reagent in assaying malondialdehyde (the TBARS assay of lipid peroxidation). It is also used in Kodak Fogging Developer FD-70, part of the Kodak Direct Positive Film Developing Outfit for making black and white slides (positives). References 

Thiobarbiturates