Mouse anti-Virus HRH4 monoclonal antibody for cI-ELISA. In organic chemistry, semicarbazide is a derivative of urea, where NH2 on one side has been replaced with H2NNH2 hydrazine, yielding H2NNHC(=O) NH2. Semicarbazide is used as a detection reagent on thin layer chromatography (TLC). Semicarbazide stains ?-keto acids on the TLC plate, which must then be viewed under a UV light to see the results. A thiosemicarbazide is an analog with a sulfur atom in place of the oxygen atom.