Performance assessment of a portable mass spectrometer using a linear ion trap operated in non‐scanning mode

Abstract

The portable mass spectrometer is predicted to achieve a mass resolution of better than one mass unit providing that helium buffer gas is used. An additional cooling sequence has to be added prior to moving the operating point toward the apex. Copyright © 2016 John Wiley & Sons, Ltd.

Accurate modelling of small-scale linear ion trap operating mode using He buffer gas to improve sensitivity and resolution for in-the-field mass spectrometry

“…The ions are injected with 3 eV energy. For more details on ion injection simulation with experimental results, see references 12,14 .…”

“…For ion injection, the trap is operated in RF only mode with U 0 = 0 V and V 0 = 28.9 V for m/z 100 ions. We have previously estimated that the trap filling time (or maximal residence time of ions in the trap) from a short-time pulse ion injection is almost 150 µs for m/z 100 ions 14 . Additional computations have been performed with the same design and operating conditions except that simulation tool involves collisional processing.…”

“…For ion cooling, the trap is operated in RF only mode with U 0 = 0 V, and V 0 = V apex = 28.9 V for m/z 100 ions and V 0 = V apex = 86.7 V for m/z 300 ions. The initial ion distributions of cooling step are the ion distributions at the end of collision-free injection 14 . The main objective is to determine the influence of the collisions on the number of confined ions and on the evolution of position and velocity ion states, and the minimum time of the ion cooling step, time from which we can consider that the ion cloud has reached the equilibrium state.…”

“…An experimental mass separation of 4 u was obtained for methyl benzoate, 2-nitrotoluene and dimethyl methylphosphonate 13 . Since then the authors have shown the possibility of decreased mass separation (increased resolution) with spatial-and velocity-reduced ion distributions, when the LIT is operated close to the stability diagram apex 14 . The conclusions of these studies led the authors to simulate the use of He buffer gas cooling in order to obtain a mass separation of 1 u.…”

Resonance methods in quadrupole ion traps

“…Thus, the intensity of a single m/z species is monitored, and a full scan mass spectrum cannot be collected unless the experiment is repeated for each m/z. A similar experiment was implemented on a linear ion trap made using digital light processing technology [217], and it has recently been calculated that a mass resolution of 1 amu should be possible in the non-scanning mode [218].…”