Nassim Maarouf Mesli, Charity D Yongo Luwawa, Ida Boccino, Karen C Waldron, William D Lubell
A rapid, nondestructive NMR method for quantifying trifluoroacetic acid (TFA) in peptides without sample weighing is reported by correlating 1H and 19F integrations using fluorinated alcohols as internal standards in D2O. After benchmarking the internal standards with a fluorinated dipeptide at different temperatures, 1H integration strategies were studied and applied to peptides possessing diverse amino acid residues and up to four potential positive charges. The method effectively quantifies TFA, offering utility for peptide salt composition assessment without sample destruction.