Method to extract and use time-resolved ion clouds from a spectrometric data set

A method is proposed for extracting single-particle and/or single-cell events from a spectrometric data set comprising intensity values. A respective intensity value is proportional to the number of ions collected by a detector in a given time interval. The method comprises: grouping (22) the intensity values into sets of groups of consecutive intensity values, a respective set being <b>characterised by</b> a distinct group size of consecutive intensity values; determining (23) a threshold value separating a background from candidate event intensity values; calculating (24) a dissolved intensity as a mean of the intensity values forming a background signal; carrying out (25) a first candidate event identification by obtaining candidate peak groups based on a feature characterising a respective group; carrying (26) out a second candidate event identification by obtaining ion cloud groups based on the threshold value; carrying out (27) a true event identification by comparing the first and second candidate event identifications to obtain one or more ion cloud group events for a respective group size; and summing (28) the intensity values of a respective ion cloud group event and subtracting the dissolved intensity as scaled from the summed intensity values of the respective ion cloud group event to obtain a total intensity value per particle or cell.