To see a picture of the drift tube (free-standing), click here.

The main advantage of this design over the injected-ion drift tube is the increase in resolving power that is attained. The resolving power of the drift tube is based on the following expression:

Thus, the resolving power can be increased by a factor equal to the square root of the increase in the electric field strength. At the low pressures (1-5 torr) used in the injected-ion drift tube, high electric field strengths cannot be achieved, due to the breakdown potential of the buffer gas. However, at higher buffer gas pressures, the field strength (and thus resolving power) can be increased. Another advantage of the high pressure drift tube is that ions are not injected; thus, the ions are analyzed in a much gentler manner, allowing conformations formed in the source to be preserved.

An example drift time distribution recorded for a small organic hexamer using this drift tube design is shown below.

Relevant Publications:
Srebalus, C. A.; Li, J.; Marshall, W. S.; Clemmer, D. E. Determining Synthetic Failures in Combinatorial Libraries by Hybrid Gas-Phase Separation Methods, J. Am. Soc. Mass Spectrom. 2000, 11, 352-355.

Li, J.; Taraszka, J. A.; Counterman, A. E.; Clemmer, D. E. Influence of solvent composition and capillary temperature on the conformations of electrosprayed ions:  unfolding of compact ubiquitin conformers from pseudonative and denatured solutions, Int. J. Mass. Spectrom. 1999, 185/186/187, 37-47.

Counterman, A. E.; Valentine, S. J.; Srebalus, C. A.; Henderson, S. C.; Hoaglund, C. S.; Clemmer, D. E. High-Order Structure and Dissociation of Gaseous Peptide Aggregates that are Hidden in Mass Spectra, J. Am. Soc. Mass Spectrom. 1998, 9, 743-759.

        Last modified:   October 23, 2006