High resolution accurate mass measurement of product ions formed in an electrospray source on a sector instrument

Abstract
The high resolution accurate mass measurement of product ions formed by collisionally activated dissociation in an electrospray source has been achieved using a reversed‐geometry double‐focusing mass spectrometer and accelerating voltage scans. Accurate mass measurements of product ions from angiotensin I, angiotensin II, leucine enkephalinamide, substance P (1–9) and a synthetic compound of pharmaceutical interest were obtained with an average error of <5 ppm.