A high voltage RF oscillator for driving multipole ion guides.

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 V(p-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.