Implementation of a Charge-Sensitive Amplifier without a Feedback Resistor for Charge Detection Mass Spectrometry Reduces Noise and Enables Detection of Individual Ions Carrying a Single Charge

Aaron R Todd; Andrew W Alexander; Martin F Jarrold

doi:10.1021/jasms.9b00010

Implementation of a Charge-Sensitive Amplifier without a Feedback Resistor for Charge Detection Mass Spectrometry Reduces Noise and Enables Detection of Individual Ions Carrying a Single Charge

J Am Soc Mass Spectrom. 2020 Jan 2;31(1):146-154. doi: 10.1021/jasms.9b00010. Epub 2019 Dec 17.

Authors

Aaron R Todd¹, Andrew W Alexander¹, Martin F Jarrold¹

Affiliation

¹ Chemistry Department, Indiana University, Bloomington, Indiana 47405, United States.

PMID: 32881508
DOI: 10.1021/jasms.9b00010

Abstract

Charge detection mass spectrometry (CDMS) depends on the measurement of the charge induced on a cylinder by individual ions by means of a charge-sensitive amplifier. Electrical noise limits the accuracy of the charge measurement and the smallest charge that can be detected. Thermal noise in the feedback resistor is a major source of electrical noise. We describe the implementation of a charge-sensitive amplifier without a feedback resistor. The design has significantly reduced 1/f noise facilitating the detection of high m/z ions and substantially reducing the measurement time required to achieve almost perfect charge accuracy. With the new design we have been able to detect individual ions carrying a single charge. This is an important milestone in the development of CDMS.