Patent ID: 8384022

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 during operation of the ion trap mass analyzer, the method comprising steps of: (a) selecting an analytical scan rate at which to operate the mass spectrometer; (b) identifying, for each of a plurality of ion types produced from at least one calibrant material and having respective mass-to-charge ratios, an optimum resonant ejection voltage amplitude at which a mass peak quality value is optimized when the ion trap mass analyzer is operated at the selected scan rate, the mass peak quality value representative of one or more mass peak characteristics observed during operation of the ion trap mass analyzer; (c) determining a best-fit function from the identified optimum resonant ejection voltage amplitudes and the mass-to-charge ratios, the best-fit function of the form V reseject =m c (a r +b r m), where V reseject is a variable representing resonant ejection voltage amplitude, m is a variable representing mass-to-charge ratio and a r , b r and c are constants determined by a fitting procedure, such that 0.40≦c≦0.60; and (d) storing information representing the best-fit function derived in step (c).