NEWION SOURCE, IONTRANSFER OPTICS, AND ION ACCUMULATION FORA9.4 TESLAFT-ICR MASS SPECTROMETER

摘要

The custom-built 9.4 T FT-ICR mass spectrometer at NHMFL has set several benchmarks for FT-ICR MS technology. To further advance instrument performance, we couple our innovative ICR technology with a novel dual ion funnel (Figure 1) developed at Pacific Northwest National Laboratory(PNNL). The dual ion funnel replaces the former lens/skimmer (Figure 2) and has demonstrated more than ten-fold higher ion transmission efficiency (Figure 3). The ESI needle is biased at 2.5 kV. Ions emanating from the ESI needle are introduced into vacuum region via a heated capillary, biased at 330 V, and heated to ～100°C. Ions are focused by a dual stage ion funnel, each located in a differentially pumped vacuum stage. A linear dc gradient is applied across the ion funnel by applying a dc voltage to the first and last plates of the ion funnel with a resistor chain connecting all intervening plates. The dc voltages applied on funnel1 are 310 V and 150 V, and on funnel 2 are 130 V and 35 V. Opposite rf phases signals are applied to adjacent ring electrodes of each ion funnel. (1120 kHz, 150 Vp-p for funnel 1, and 1150 kHz, 170 Vp-p for funnel 2.) The quadrupole ion guide consists of four 6.35mmODtitanium rods, with an inscribed diameter of 5.33 mm. Adjacent rods receive opposite phases of rf with frequency 2.0 MHz, and ～300 Vp-p.