Study of SI-traceable purity assessment of bovine lactoferrin using mass balance approach and amino acid-based isotope dilution liquid chromatography-mass spectrometry

•The accurate procedures for the quantification of bovine lactoferrin using SI traceable mass balance method and amino acid (AA)-based IDMS are proposed.•The mass balance method was achieved by deducting impurities of related structural impurities, water, ignition residue, and volatile organic compounds with complementary and independent techniques.•Ile, Val, and Phe were selected as the targeted AAs and hydrolysis conditions were optimized in AA-based IDMS.•The uncertainty of bLF purity assessed was in significantly low level (<2%).