Patent ID: 7804065

Claim:
A method of calibrating an ion trap mass analyzer having a plurality of electrodes to which a main RF trapping voltage and a resonant ejection voltage are applied, the main RF trapping voltage and resonant ejection voltage defining a resonant ejection voltage phase, the method comprising steps of: a) selecting a resonant ejection voltage phase at which a peak quality value representative of one or more ejection peak characteristics is optimized; b) for each of a plurality of calibrant ions having different mass-to-charge ratios, identifying a resonant ejection voltage amplitude at which the peak quality value is optimized when the ion trap mass analyzer is operated at the selected resonant ejection voltage phase; c) deriving a relationship between mass-to-charge ratio and resonant ejection voltage amplitude from the values of resonant ejection voltage amplitudes acquired in step (b); and d) storing data representing the relationship derived in step (c).