An ultrafast peptide mapping method using a rapid in-solution trypsin digestion was developed to determine site specific oxidation of mAbs.

In the method, UV peak areas of oxidized and native peptides separated by RP-HPLC were used to estimate % oxidation.

The method can monitor oxidation of methionine and tryptophan triggered by TBHP, photo-irradiation, or elevated temperatures.

The method is reproducible, and can be implemented in regular laboratories without mass spectrometers.