Substance identification method and mass spectrometry system used for the same method

摘要

An identification probability estimation model, which shows the relationship between the S/N ratios of MS1 peaks and the cumulative number of the peaks in the case where MS2 measurements and identifications is performed in descending order of S/N ratio, is created beforehand from the S/N ratios of MS1 peaks as well as the results of MS1 or MS2 measurements and identifications (success or failure) performed for a number of fractionated samples obtained from a predetermined sample. Based on an evaluated value of the identification probability and that of the identification probability increment, an order of priority of MS2 measurements for a plurality of MS1 peaks is determined, and an MS2 measurement sequence which gives the maximal expectation value of the number of substances to be identified under a limitation on the number of MS2 measurements or other factors is determined.

主权项

1. A substance identification method for identifying a substance contained in each of a plurality of fractionated samples obtained by separating various substances contained in a sample according to a predetermined separation parameter comprising:
a) an identification probability estimation model creation step, in which an identification probability estimation model is created by using peak information values showing information on MSn-1 peaks found by MSn-1 measurements (where n is an integer equal to or greater than two) for a plurality of fractionated samples obtained from a predetermined sample and results of substance identification based on results of MSn measurements using each of the MSn-1 peaks as a precursor ion, the model showing a relationship between peak information values of a plurality of MSn-1 peaks originating from a same kind of sample and a cumulative number of peaks successfully identified through a series of MSn measurements and identifications in which the MSn-1 peaks are sequentially selected as a precursor ion in order of the s peak information values thereof, and identification probability estimation model information representing the identification probability estimation model is stored; b) a peak information value acquisition step, in which, after an MSn-1 measurement for at least one fractionated sample obtained from a target sample to be identified has been completed, peak information value is obtained for each of a plurality of MSn-1 peaks selected as candidates of the precursor ion from among the MSn-1 peaks found by the MSn-1 measurement; c) an identification probability estimation step, in which an estimated value of the identification probability of each of the MSn-1 peaks is calculated from the peak information values of the MSn-1 peaks obtained in the peak information value acquisition step, with reference to the identification probability estimation model derived from the identification probability estimation model information; d) an identification probability increment estimation step, in which an estimated increment of the identification probability, which shows a degree of increase in the identification probability achieved by performing an MSn measurement for a same MSn-1 peak a plurality of times and accumulating the results of the measurement, is calculated from the estimated value of the identification probability calculated for each of a plurality of MSn-1 peaks selected as the candidates of the precursor ion in the identification probability estimation step; e) an MSn measurement order determination step, in which, for each of a plurality of MSn-1 peaks selected as the candidates of the precursor ion, an order of priority of the MSn measurements for a plurality of MSn-1 peaks under the condition that a plurality of MSn measurements are allowed for the same MSn-1 peak is determined based on the estimated value of the identification probability of each MSn-1 peak calculated in the identification probability estimation step and the increment of the identification probability estimated in the identification probability increment estimation step; f) an MSn spectrum acquisition step, in which MSn spectra are obtained by performing an MSn measurement for each of a plurality of fractionated samples obtained by separating the target sample to be identified according to the predetermined separation parameter and fractionating the sample, using the order of priority determined in the MSn measurement order determination step; and g) a substance identification step, in which a substance contained in each of the plurality of fractionated samples is identified based on the MSn spectra obtained in the MSn spectrum acquisition step.