A method of processing mass spectral data is disclosed comprising digitizing a first signal output from an ion detector to produce a first digitized signal. A first set of peaks in the first digitized signal is detected and the arrival time To and peak area So of one or more peaks in the first set of peaks are determined thereby forming a first list of data pairs, each data pair comprising an arrival time value and a peak area value. One or more data pairs from the first list are then filtered out thereby forming a second reduced list, wherein a data pair is filtered out, attenuated or otherwise rejected from the first list if the peak area value of a data pair in the first list is determined to be less than a threshold peak area.