Enhancing the performance of LC-MS for intact protein analysis by counteracting the signal suppression effects of trifluoroacetic acid during electrospray.

We develop an acidic vapor assisted electrospray ionization strategy within an enclosed electrospray ionization source to counteract the ion suppression effects caused by trifluoroacetic acid. The mass spectrometry signal intensity of intact proteins was improved 10 times and the number of valid signals for E. coli intact protein samples was improved 96% by using this strategy.