Methods for labeling amine-containing compounds

A method for labeling and, optionally, analyzing, a N-glycan, amine-containing amino acid, amine-containing peptide, amine-containing protein, glycosylamine, or other amine-containing compound in a sample, said method comprising:

• (a) mixing said N-glycan, amine-containing amino acid, amine-containing peptide, amine-containing protein, glycosylamine, or other amine-containing compound in a solution with a labeling compound (“Activated Procaine”) with the structure
• or a solvate or a salt of said labeling compound, thereby creating a labeling mixture, and
• (b) conducing said labeling at a labeling temperature of between 10° C.±2° C. and 60° C.,
• thereby creating labeled, fluorescent, mass spectrometry-active derivatives of said N-glycans, of said amine-containing amino acids, of said amine-containing peptides, of said amine-containing proteins, of said glycosylamines, or of said other amine-containing compounds in said sample.