AN AERODYNAMIC DRAG MODEL FOR PROTEIN IONS

The energy losses of protein ions passing through a collision cell fil led with inert gas have been modeled as the aerodynamic drag on a proj ectile at high Knudsen number. When applied to the energy loss data of Covey and Douglas (J. Am, Sec. Mass Spectrom. 1993, 4, 616-623) with drag coefficients from the gas dynamics literature, derived protein cr oss sections are similar to 0.8 of those found with the simple collisi on model used by Covey and Douglas.