A method of mass spectrometry comprising: digitising a first signal output from an ion detector to produce a first digitised signal; determining or obtaining a second differential or a second difference of said first digitised signal; determining the arrival time T 1 or the mass or mass to charge ratio m 1 of one or more first ions from said second differential or said second difference of said first digitised signal; determining the intensity I 1 of said one or more first ions; digitising a second signal output from said ion detector to produce a second digitised signal; determining or obtaining a second differential or a second difference of said second digitised signal; determining the arrival time T 2 or the mass or mass to charge ratio m 2 of one or more second ions from said second differential or said second difference of said second digitised signal; determining the intensity I 2 of said one or more second ions; and determining whether the determined arrival time T 2 of said one or more second ions falls within a time period, time window or memory array element within which the determined arrival time T 1 of said one or more first ions falls, wherein if it is determined that the determined arrival time T 2 of said one or more second ions falls within said time period, time window or memory array element within which the determined arrival time T 1 of said one or more first ions falls then said method further comprises: (i) determining an average arrival time T' of said one or more first ions T 1 and said one or more second ions T 2; and/or (ii) determining the combined intensity I' of said one or more first ions I 1 and said one or more second ions I 2; or determining whether the determined mass or mass to charge ratio m 2 of said one or more second ions falls within a mass window or pre-determined memory location within which the determined mass or mass to charge ratio m 1 of said one or more first ions falls, wherein if it is determined that the determined mass or mass to charge ratio m 2 of said one or more second ions falls within a mass window or pre-determined memory location within which the determined mass or mass to charge ratio m 1 of said one or more first ions falls then said method further comprises: (i) determining an average mass or mass to charge ratio m' of said one or more first ions m 1 and said one or more second ions m 2; and/or (ii) determining the combined intensity I' of said one or more first ions I 1 and said one or more second ions I 2. digitising a first signal output from an ion detector to produce a first digitised signal; determining or obtaining a second differential or a second difference of said first digitised signal; determining the arrival time T 1 or the mass or mass to charge ratio m 1 of one or more first ions from said second differential or said second difference of said first digitised signal; determining the intensity I 1 of said one or more first ions; digitising a second signal output from said ion detector to produce a second digitised signal; determining or obtaining a second differential or a second difference of said second digitised signal; determining the arrival time T 2 or the mass or mass to charge ratio m 2 of one or more second ions from said second differential or said second difference of said second digitised signal; determining the intensity I 2 of said one or more second ions; and determining whether the determined arrival time T 2 of said one or more second ions falls within a time period, time window or memory array element within which the determined arrival time T 1 of said one or more first ions falls, wherein if it is determined that the determined arrival time T 2 of said one or more second ions falls within said time period, time window or memory array element within which the determined arrival time T 1 of said one or more first ions falls then said method further comprises: (i) determining an average arrival time T' of said one or more first ions T 1 and said one or more second ions T 2; and/or (ii) determining the combined intensity I' of said one or more first ions I 1 and said one or more second ions I 2; or determining whether the determined mass or mass to charge ratio m 2 of said one or more second ions falls within a mass window or pre-determined memory location within which the determined mass or mass to charge ratio m 1 of said one or more first ions falls, wherein if it is determined that the determined mass or mass to charge ratio m 2 of said one or more second ions falls within a mass window or pre-determined memory location within which the determined mass or mass to charge ratio m 1 of said one or more first ions falls then said method further comprises: (i) determining an average mass or mass to charge ratio m' of said one or more first ions m 1 and said one or more second ions m 2; and/or (ii) determining the combined intensity I' of said one or more first ions I 1 and said one or more second ions I 2.