Pulsed Mass Calibration in Time-of-Flight Mass Spectrometry

A system comprising:

• a time-of-flight mass spectrometer comprising an ion source;
• a chromatographic system operationally connected to the time-of-flight mass spectrometer;
• a source of calibrant material in interruptable fluid communication with the time-of-flight mass spectrometer;
• and
• a control unit configured to
• introduce a sample to the chromatographic system,
• introduce the calibrant material from the source of calibrant material into the time-of-flight mass spectrometer after the sample is introduced to the chromatographic system and before an analysis of the sample is complete, wherein the introduction of the calibrant material is such that calibrant material and sample material are not present contemporaneously at the ion source of the time-of-flight mass spectrometer,
• acquire a multiplicity of mass spectra of the calibrant material during the analytical run, and
• calculate a multiplicity of mass calibrations on the basis of mass spectra obtained from the calibrant material introduced during the analytical run.