Mass analysis data analyzing method and apparatus

摘要

A method and apparatus for estimating the structure of an unidentified substance produced from an original substance having a known structural formula through partial structural change caused by metabolism or the like. A mass difference between a product ion, originating from the unidentified substance and having a partial structure including a structural change site, and a product ion, originating from the original substance and having a partial structure prior to the structural change, is equal to the mass difference between the original substance and the unidentified substance. Therefore, when pairs of product ions each having such a mass difference are selected to be compared with partial structures obtained from the known structural formula of the original substance, a minimum common partial structure having the structural change site is obtained.

主权项

1. A mass analysis method for estimating a structure of an unidentified substance having a partially different structure from a structurally known substance based on mass analysis data about the structurally known substance and mass analysis data about fragments obtained by one or more dissociation operations for the structurally known substance, the mass analysis data analyzing method comprising:
performing one or more dissociation operations for the unidentified substance by using a mass analyzer to obtain mass analysis data about the unidentified substance and mass analysis data about fragments; determining a candidate a structural difference between the structurally known substance and the unidentified substance based on a mass difference between the structurally known substance and the unidentified substance obtained from the mass analysis data about both of the substances; selecting a plurality of pairs each composed of a mass of a fragment originating from the structurally known substance and a mass of a fragment originating from the unidentified substance, where, in each of the pairs, a mass difference between the mass of the fragment obtained from the mass analysis data about the fragment originating from the structurally known substance and the mass of the fragment obtained from the mass analysis data about the fragment originating from the unidentified substance is equal to the mass difference corresponding to the candidate structural difference; determining a minimum common partial structure by using information about partial structures presumed from the masses of the fragments originating from the structurally known substance paired with the fragments originating from the unidentified substance in the selected pairs on an assumption that the fragments originating from the unidentified substance included in the plurality of selected pairs correspond to partial structures different from one another; and estimating a candidate of the structure of the unidentified substance based on the determined minimum common partial structure, a known structure of the structurally known substance and the candidate structural difference, outputting the candidate of the structure of the unidentified substance, whereby identifying the unidentified substance on which the one or more dissociation operations are performed by the mass analyzer is improved by determining the minimum common partial structure.