Abstract: There is provided a method of identifying spurious peaks in a mass spectrum produced from a time-varying transient signal detected in a mass spectrometer. The method comprises the steps of generating, using a regularized inversion algorithm having one or more adjustable parameters, a first mass spectrum from the time-varying transient signal, according to a first set of values of said one or more adjustable parameters. Generating, using the regularized inversion algorithm, one or more perturbed mass spectra from the transient signal, according to one or more respective perturbed versions of the first set of values. Identifying one or more spurious peaks in the first mass spectrum by comparing the first mass spectrum with at least one of the perturbed mass spectra. There are also provided corresponding systems and computer readable media.