Creative Proteomics provides N-terminal sequence analysis by both Edman and Mass spectrometry of therapeutic proteins, monoclonal antibodies and protein vaccines. In protein N-terminal sequence analysis, proteins are first modified with phenylisothiocyanate (PITC). Subsequently, the derivatized terminal amino acid is removed by acid cleavage in a form of phenylthiohydantoin (PTH) derivative and a new α-amino group on the next amino acid is now available for the next round of reaction with PITC. Protein sequence is therefore being analyzed in through a serious reaction of PITC addition, and cleavage of one PTH at each time for analysis.