Field Switching Inside Drift Tube

3 Ion Trap for Injecting Ions into a Drift Tube 

Although an ESI source provides a continuous flow of ions, the amount of this ion flux used in a drift tube is limited by the duty cycle of the ion shutter. One method to improve S/N with drift tubes operated at subambient pressure is to place a quadru-pole ion trap between source and drift tube. Ions from the source could be accumulated in the trap and then injected into the IMS drift tube. Improvements in S/N by factors of 10 to 30 were reported, and the experimental duty cycle was nearly 100%. Detection limits of 1.3 pmol for the oligosaccharide maltotetraose were obtained in 10 s or less. 

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