High resolution accurate mass measurements of FAB-generated ions by use of peak matching and multichannel analyzer techniques.

Abstract

Accurate mass measurement at a resolution of 10,000 has been performed with very small ion currents generated by fast atom bombardment ionization. With the use of a peak matching unit to switch accelerating voltage and a multi-channel analyzer to acquire the data, determination of exact mass can be routinely made with less than 5 ppm error on ion currents of insufficient intensity for accurate peak matching in the conventional mode. Glycerol cluster ions generated during the FAB experiment are suitable mass references. Calibration of the peak matching unit voltage offset allows the use of a single reference mass for exact mass calculation.