Phenyl isothiocyanate, often abbreviated as PITC or Edman's Reagent, is a PTC-amino acid derivative that cleaves the amino end of a polypeptide. It has a structure like this:

 / __ \
/ /  \ \---N===C===S
\ \__/ /

This is the first step in the Edman Degradation process, which analyzes polypeptides for their amino acid sequence and content. Before acid hydrolysis can begin, the polypeptide must be trated with Edman's Reagent to transform it into a PTC-polypeptide chain. The pH must be set at 9.0 for this process to occur smoothly.