Traceable amino acid analyses of proteins and peptides by isotope-dilution mass spectrometry using precolumn derivatization reagent.

We have developed an accurate and traceable quantitation method of proteins and peptides by isotope-dilution mass spectrometry with the precolumn derivatization for hydrolyzed amino acid. This method utilized N-butylnicotinic acid N-hydroxysuccinimide ester iodide as the derivatization reagent and C-30 reversed phase column for the separation. Quantitative results of porcine insulin and human serum albumin obtained from the hydrolyzed six or seven amino acids showed a good agreement, with less than 3% of the expanded uncertainties. This method allows more accurate and more robust amino acid analysis in comparison with non-labeled methods.