Mass spectrometry (MS) has emerged as a powerful analytical technique for direct quantification of intact proteins. In quantifying intact proteins, selected ion monitoring (SIM) and multiple reaction monitoring (MRM) methods have been reported by using triplequadrupole (QQQ) mass spectrometry. Because of a low dynamic range, there is lack of studies of intact protein quantification using quadrupole time-of-flight (Q-TOF) mass spectrometry. However, Q-TOF has the advantages of high-resolution accurate mass.
In this study, we aimed to identify, investigate, and demonstrate the performance of multiple ion chromatogram (MIC) for direct quantification of intact proteins using a Shimadzu LCMS-9030 Q-TOF mass spectrometry.