Double-Helix Electrode Ion Funnel: A New Ion Funnel Design with an Extended Mass Range

The development of an atmospheric pressure interface (API) with a high ion transfer efficiency and wide mass range is advantageous for the performance improvement of mass spectrometry (MS) instruments. In this work, a novel ion guide, namely, the double-helix electrode ion funnel (DHE-IF), has been developed to enhance the ion transmission over a wide mass range in the rough vacuum region. The DHE-IF consists of two funnel-shaped helix electrodes. There are almost no potential "traps" along the central axis of DHE-IF due to the continuous double-helix electrode structure compared to the stacked ring ion funnel. The electrode design of the DHE-IF assembly was guided by ion trajectory simulations. After being fabricated, DHE-IF was integrated into an ESI-TOF-MS platform for tests. A conventional stacked ring ion funnel (IF) was also tested for comparison. The experimental results showed that DHE-IF extended the transmission window of the IF and improved the efficiency of the simultaneous transferring of low and medium m/z ions. In addition, the intensities of caffeine ions (m/z = 195) and reserpine ions (m/z = 609) were enhanced by more than 50% and 10%, respectively. These values were compared with the results obtained by the IF. The DHE-IF is expected to be widely used as an ion import device in MS instruments, which is due to its improved performance and advantages in, e.g., integration and power supply design.