Charge Detection Mass Spectrometry for Single Ions with an Uncertainty in the Charge Measurement of 0.65 e.

Charge detection mass spectrometry (CDMS) provides a direct measure of the mass of individual ions through nondestructive, simultaneous measurements of the mass to charge ratio and the charge. To improve the accuracy of the charge measurement, ions are trapped and recirculated through the charge detector. By substantially extending the trapping time, the uncertainty in the charge determination has been reduced by a factor of two, from 1.3 elementary charges (e) to 0.65 e. The limit of detection (the smallest charge that can be reliably measured) has been reduced by about the same proportion, from 13 to 7 e. The more precise charge measurements enable a substantial improvement in the mass resolution, which is critical for applications of CDMS to mixtures of high mass ions.