Collisional fragmentation

Although comets are not expected to have experienced the thermal processing that asteroids have, some of the larger KBOs and Oort cloud objects may have been heated by decay of radionuclides. The relative proportions of rock and ice may determine the amount of heating, as radionuclides occur in the rock fraction. Comets and asteroids may have had similar impact histories, and many of these bodies may now be collisional fragments. 

M. J. Huddleston, M. F. Bean, and S. A. Carr, Collisional fragmentation of glycopeptides by electrospray ionization LC/MS and LC/MS/MS Methods for selective detection of glycopeptides in protein digests, Anal. Chem., 65 (1993) 877-884. 

Collisional fragmentation cells have been used in triple quadrupole MS-MS instruments for organic mass spectrometer for some time. However, scattering losses of Ce+ analyte ions in ICP-MS were found to be greater than the reduction in the CeO+ signal. It is unlikely that collisional fragmentation will be effective for reduction of spectral overlaps in ICP-MS. 

Figure 6 Schematic of collision-induced dissociation (CID) in the quadrupole ion trap (QIT) (MS2 experiment). In separate events, ions from the source are accumulated and trapped in the space at the center of the electrodes (a). Ions with a specified m/z value are retained in the trap and all others ejected (b). The specified ions are then collisionally fragmented by axial excitation between the two end caps (c). The resulting product ions are then sequentially ejected to generate the product ion spectrum (d). In an MS3 experiment, one of these product ions may be selectively retained in the trap, excited, and fragmented.

Detector MS, PE Sciex API III, heated nebulized interface, corona discharge needle +4 xA, nebulizer probe 500°, nebulizing gas was air at 2 L/min and 80 psi, curtain gas flow was nitrogen at 0.9 L/min, sampling orifice +45 V, dwell time 400 ms, interface heater 60°, electron multipher-3.7 kV, collision gas was argon 355 x 10 atoms/cm, first quad-rupole filter admits m/z 276 (cyclobenzaprine) and 295 (trimipramine, collisional fragmentation at second filter, monitor m/z 215 (cyclobenzaprine) and 208 (trimipramine) at third quadrupole filter... 

Collisional fragmentation— The polyatomic ion is broken apart or fragmented by the process of multiple collisions with the gaseous atoms. 

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