Abstract
The efficiency of in-trap fragmentation in a low-pressure linear ion trap (LIT), using dipolar excitation, is dependent upon the choice of both the excitation q and the drive frequency of the quadrupole. In the work presented here, fragmentation efficiencies have been measured as a function of excitation q for drive frequencies of 816 kHz and 1.228 MHz. The experiments were carried out by fragmenting reserpine (609.23→448.20 Th and 397.21→365.19 Th transitions) and caffeine (195→138 Th and 138→110 Th transitions). The data showed that the onset of efficient fragmentation occurred at a lower Mathieu q for the LIT operated at 1.228 MHz when compared with the LIT operated at 816 kHz. A comparison of the fragmentation efficiency curves as a function of pseudo-potential well depth showed that the onset of fragmentation is independent of the drive frequency. In addition, a comparison of the fragmentation efficiency curves showed that all four of the precursor ions fragmented within a range of four V of pseudo-potential well depth. The choice of an appropriate excitation q can then be determined based upon a minimum pseudo-potential well depth, quadrupole field radius, drive frequency, and the mass of interest. Fragmentation efficiencies were also found to be significantly greater when using the higher drive frequency.
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Published online May 10, 2007
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Collings, B.A. Fragmentation of ions in a low pressure linear ion trap. J Am Soc Mass Spectrom 18, 1459–1466 (2007). https://doi.org/10.1016/j.jasms.2007.05.002
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DOI: https://doi.org/10.1016/j.jasms.2007.05.002