Method for charge calibration of cdms measurements of charged particles

A charge detection mass spectrometer, comprising:

• an electrostatic linear ion trap (ELIT) or an orbitrap, including a charge detection cylinder,
• a charge sensitive amplifier configured to detect charges induced on the charge detection cylinder,
• at least one antenna for inducing charges on the charge detection cylinder,
• at least one voltage source,
• at least one memory, and
• at least one processor configured to execute instructions stored in the at least one memory to cause the at least one processor to calibrate charge values of charged particles to be measured by the charge detection mass spectrometer by (i) controlling the at least one voltage source to apply a constant amplitude, variable frequency signal to the at least one antenna to induce respectively constant amplitude charges on the charge detection cylinder over a range of frequencies, and (ii) processing charge detection signals produced by the charge sensitive amplifier in response to detection of the constant amplitude charges induced on the charge detection cylinder over the range of frequencies to determine a frequency-dependent correction factor to apply to and calibrate the charge values of charged particles measured by the charge detection mass spectrometer.

A charge detection mass spectrometer, comprising:

• an electrostatic linear ion trap (ELIT) or an orbitrap, including a charge detection cylinder,
• a charged particle generator to generate charged particles and to supply the generated charged particles to the ELIT or orbitrap,
• at least one memory, and
• at least one processor configured to execute instructions stored in the at least one memory to cause the at least one processor to calibrate charge values of charged particles to be measured by the charge detection mass spectrometer by (i) controlling the charge detection mass spectrometer to measure mass-to-charge and charge values of charges induced on the charge detection cylinder by charged particles generated by the charged particle generator from a number of different sample species, and (ii) to process charge detection signals produced by the charge sensitive amplifier in response to the measured mass-to-charge and charge values of the charged particles for the number of different sample species to determine an alignment correction factor, in which the measured charge values of charged particles generated from the number of different sample species align with integer charge values, to apply to and calibrate the charge values of charged particles to be measured by the charge detection mass spectrometer.