Charge detection mass spectrometry for single ions with a limit of detection of 30 charges

► A new charge detection mass spectrometer is described. ► Ions are energy selected prior to entering a cone trap with an image charge detector. ► A limit of detection of 30 elementary charges is achieved. ► The average uncertainty in the charge measurements is 3.2 elementary charges. ► Mass distributions measured for BSA (66.4 kDa) show monomer and multimer ions.