| 摘要 |
A method of mass spectrometry comprising digitising at least one individual signal or transient (1, 2 figures 1A/B) which may arise from the detector or sensor of a time of flight mass spectrometer, and determining in relation to the digitised signal or transient an indication of overlap or coalescence of ion arrivals (9 figure 1B or 12, figure 2) in the digitised signal or transient, or one or more ion arrival envelopes in the digitised signal or transient, and subsequently marking or flagging the digitised signal or transient as suffering from overlap or coalescence of ion arrivals based on the indication. The invention therefore initially identifies whether a distorted digitised waveform was caused as a result of two ions being detected coincidentally or close to each other so as to cause coalescence or overlap of the waveform, and this information is inserted along with other information when creating composite spectra such as time-intensity pairs. Identification of coalescence/overlap may involve identifying the geometrical features of the ion arrival envelope of the digitised signal/transient. For example features such as shape, symmetry, peak purity, peak area, intensity, standard deviation, centre of mass, peak width and kurtosis may be used along with a comparison of these values against a known calibrated value. The marked or flagged intensity/time profiles, peak profiles or the digitised data may be further subject to a process of deconvolution to separate out the two or more constituent peaks. A further method is disclosed in which statistics on the number of flagged waveforms encountered is collected (see figure 3). A further method is disclosed comprising summing the plurality of digitised signals or transients to generate a composite mass spectral data , and whereby the peak profile, mass to charge ratio and intensity of the data is monitored to determine an indication of overlap or coalescence |
