Methods and apparatuses for producing mass spectrum data

The present invention is concerned with methods and apparatuses for generating mass spectrum data using a mass spectrometer by subtracting noise mass spectrum data representative of noise in the mass spectrometer from signal mass spectrum data representative of the mass/charge ratio of ions in a sample material. This produces a modified signal mass spectrum data representative of the mass/charge ratio of ions in the sample material. The method includes acquiring and subtracting noise mass spectrum data representative of noise in the mass spectrometer or alternatively subtracting noise mass spectrum data from a previously acquired or pre-stored noise spectrum data. Embodiments demonstrate reduced noise and in particular reduced systematic noise compared with the originally acquired signal mass spectrum data.