Determination of proteins in infant formula by high-performance liquid chromatography–electrospray tandem mass spectrometry

To determine the protein content of formula, gel electrophoresis was performed on the infant formula samples and the entire protein patterns were analyzed by nano-high performance liquid chromatography–electrospray tandem mass spectrometry (nano-HPLC/ESI/MS/MS). From the commercial infant formula profiled in this study, a total of 154 peptides, corresponding to 31 unique proteins were identified by nano-HPLC/ESI/MS/MS. Each of the identified peptides was reconfirmed by a strict integrated approach using tandem mass spectra. This protein profiling method using gel electrophoresis coupled with nano-HPLC/ESI/MS/MS and manual evaluation is a sensitive and accurate method for protein identification as well as a powerful tool for monitoring various types of food products.