Step-scan ion trap mass spectrometry for high speed proteomics

A method for obtaining a mass spectrum of ions comprising:

• trapping the ions in a quadrupole ion trap comprising a center-ring electrode and two end-cap electrodes;
• applying a first specific frequency of RF to the center-ring electrode for a first number of complete cycles of the first specific frequency of RF;
• and
• applying a second specific frequency of RF to the center-ring electrode for a second number of complete cycles of the second specific frequency of RF, wherein the second specific frequency of RF is applied beginning at phase zero, and wherein the second specific frequency of RF differs in frequency from the first specific frequency of RF by an amount Δf1.

An ion trap mass spectrometer for obtaining a mass spectrum of ions, the ion trap mass spectrometer comprising:

• a three dimensional quadrupole ion trap;
• a sequence controller comprising a programmable waveform generator for synthesizing a step scan waveform of a trapping frequency in frequency increments over a bandwidth, wherein for each step a specific frequency is held for a fixed number of complete cycles, wherein each specific frequency is changed continuously to the frequency in the next step, and wherein each specific frequency in each step starts at phase zero position;
• and
• a charge detector.