A high voltage RF oscillator for driving multipole ion guides

Abstract

A high voltage RF oscillator circuit has been designed and constructed for driving multipole ion guides. The circuit is tunable from 500 kHz to 1.5 MHz by changing a capacitor and provides 0–1000 Vp-p that is controlled by a 0–10 V input using a negative feedback circuit. This inexpensive circuit uses a set of high voltage transistors oscillating in tandem and does not require tuning of the resonance drive frequency as the oscillator automatically resonates at the (LC)−1/2 frequency. Matrix-assisted laser desorption/ionization-Fourier transform mass spectrometry (MALDI-FTMS) mass spectra were acquired using this tunable RF oscillator circuit to allow transmission of protein ions in the 8.5–39 kDa range through the quadrupole ion guide from the ion source to the mass analyzer.