External Source Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Using a Split-Pair Magnet

A new instrument has been designed, built, and tested for high performance Fourier transform ion cyclotron resonance mass spectrometry which allows operation at gas pressures of up to ~20 torr in the ion source and up to ~0.01 torr in the ion trap. FTICRMS performance is not compromised at these pressures due to an external, high throughput ion source and pulsed gas introduction/rapid gas evacuation of the vacuum chamber at the trapped ion cell. This system is the first to retain ions at 0.01 torr gas pressure in the ion trap with high sensitivity. This performance is achieved while obtaining high mass resolution and ppm mass accuracies. ,