Theoretical maximal precision for mass-to-charge ratio, amplitude, and width measurements in ion-counting mass analyzers

A theory previously developed for spectra with detector-limited (i.e., signal-independent) Gaussian-distributed noise is applied to calculate the maximal precision with which mass spectral peak parameters (mass-to-charge ratio, amplitude, width) can be determined from a discrete spectrum with source-limited Poisson-distributed noise. The precision depends in a calculable way upon the peak shape, signal-to-noise ratio, and number of data points per peak width. Those dependencies are tested by analysis of simulated data. The theory provides estimates for the precision of a repeated experiment, based on data from a single discrete mass spectrum whose parameters are extracted by a least-squares fit to a specified line shape. The relevance of the predictions to present and potential time-of-flight performance is discussed.