4- Sulfophenyl isothiocyanate

SPITC-reagent Dissolve 2.55 mg 4-sulfophenyl isothiocyanate sodium salt monohydrate (SPITC, technical grade, Sigma Aldrich, St. Louis, MO store at 4°C) in Tris-buffer at a concentration of 2.55 mg/mL. Prepare always a fresh solution and use immediately. 

Chen, P., Nie, S., Mi, W Wang, X.-C., and Liang S.-P. (2004) De novo sequencing of tryptic peptides sulfonated by 4-sulfophenyl isothiocyanate for unambiguous protein identification using post-source decay matrix-assisted laser desorption/ionization mass spectrometry. Rapid Commun. Mass Spectrom. 18,191-198. 

A-terminal labelling with phenyl isocyanate, which is a fast and quantitative reaction also applied during Edman degradation [100]. An alternative reagent is 4-sulfophenyl isothiocyanate [101]. 

Marekov, L. N., Steinert, P. M. (2003) Charge derivatization by 4-sulfophenyl isothiocyanate enhances peptide sequencing by post-source decay matrix-assisted laser des-... 

---