SGER: Charge Amplifier for Biological Mass Spectrometry

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A grant has been awarded to John C. Price for the development of a cryogenic parametric charge amplifier with improved sensitivity for biological mass spectrometry applications. A current major trend in biological mass spectrometry is extension to the megadalton mass range through the use of electrospray and laser desorption ionization techniques. Many studies of importance to biotechnology,medical diagnosis, and molecular biology are possible in this mass range,including the identification of intact viruses and study of protein/nucleic acid complexes. Soft ionization techniques produce megadalton ions with tens to thousands of elementary charges and a broad charge distribution. Existing mass spectrometers only measure the mass-to-charge ratio,and in many situations it is not possible to resolve or identify the individual charge states,so that multiple charging places severe limits on mass resolution. This problem can addressed by charge detection mass spectrometry (CD-MS), a technique in which ions are passed through a Faraday tube connected to a sensitive charge amplifier, so that the charge may be directly measured on individual ions. However, CD-MS is limited by the poor resolution of existing charge amplifiers, not better than about 50 electrons root-mean-square (e- rms). This research project will develop a new type of cryogenic parametric charge amplifier with improved sensitivity for CD-MS applications.