[tjalfe89]

The whole idea with MS is to charge the molecules either by removing an electron or adding a proton, so that the charged molecule will travel through vacum against a negative charge. I get that, as long we talk initial uncharged molecules. But what if i want to do MS on peptides? they got a overall charge for sure, lets say fx +17 or -15. What is the idea by adding a proton if the molecule is allready charged? I dont get it..