Evaluating the Dynamic Range of Quantitation of a Novel Quadrupole-Orbitrap-Linear Ion Trap Mass Spectrometer

摘要

These data show that the combination of the new ion source, the novel instrument architecture, the improved ion gating/storage mechanism, and the improvements to the ion trap detector, pre-amplifier, and electrometer result in a dynamic range of quantitation of at least 5 orders of magnitude - regardless of whether the linear ion trap or Orbitrap analyzer is selected. In one case, 6 orders of magnitude was demonstrated. The limiting factor to dynamic range appeared to be the ability of the LC column to handle high concentrations without peak broadening, and the ability to achieve acceptable blank injections from the autosampler after injecting high concentrations. The focus of further work should be on improving the dynamic range of the LC system (including the column and autosampler). One possibility would be a multiplex arrangement, using one sampler for low concentrations and another for high concentrations. It is anticipated that an upper limit of quantitation should apply to the mass spectrometer at the point where ion injection times become extremely small and the stability of the electrospray plume becomes noticeable as it is sampled for short periods. However, in these experiments there was little or no increase in RSDs at the upper levels. This would otherwise have indicated that the limit was being approached.