1. Field of the Invention
The present invention relates to an analytical method for analyzing mass spectrometric data, a mass spectrometric data analyzing apparatus, amass spectrometric data analyzing program, and a solution offering system.
2. Description of Related Art
There has been an increasing need for a mass spectrometer which has a tandem mass spectrometric function to dissociate a substance (or a parent ion) to improve the identification precision of the substance from mass spectrometric data obtained by the mass spectrometer, and to perform further mass spectrometry of the dissociated ions. The method for identifying the parent ion and for deriving the supposed structure of the parent ion with the mass spectrometric data (i.e., MS data) of the parent ion and the mass spectrometric data (i.e., MS2 data) of the dissociated ions is mainly classified into the following methods:
(1) A database retrieving method of the mass spectrometric data (i.e., the MS data) of the parent ion;
(2) A database retrieving method of the mass spectrometric data (i.e., the MS data and the MS2 data) of the parent ion and the dissociated ions; and
(3) A method for suppositions based on the mass spectrometric data (i.e., the MS data and the MS2 data) of the parent ion and the dissociated ions but not depending on the database.
On One example of the related art (2) is disclosed in JP-A-8-124519. In this disclosure, for the individual peaks of the mass spectrum or mass spectrometric data, the candidates for the ion species corresponding to the peak mass are extracted with reference to the peak database, and the candidates for the eliminated radicals corresponding to the elimination mass are extracted with reference to the elimination radical database. Moreover, the candidates for the parent ion are determined with reference to the structure constructing database which is stored with rules for constructing the parent ion from the dissociated ions and the eliminated radicals.
In an amino acid configuration analysis supporting software “SeqMS” developed by Ohsaka University, on the other hand, the related art (3) is exemplified by identifying about ten amino acid configurations of peptide without resorting to the database retrieval. This software derives the amino acid configuration candidates by the statistical procedures which are based on the graph theory using the weighting values of the dissociation probability determined empirically (or experimentally) from the mass spectrometric data of the peptide ions and their dissociated ions.
When the database retrievals of the related arts (1) and (2) are used as the method for identifying the parent ion and for deriving the supposed structure of the parent ion by the mass spectrometric data (i.e., the MS data) of the parent ion and the mass spectrometric data (i.e., the MS2 data) of the dissociated ions, however, the parent ion is difficult to identify, and the supposed structure is difficult to derive, because no data is present in the database for a substance having an unknown structure.
When the statistical processing based on the graph theory and the information processing of a numerical arrangement are performed as the method without resorting to the database retrieval, as disclosed in the related art (3), on the other hand, it is the current practice that the identification precision of the parent ion is seriously lowered to one half or less.
Therefore, a main object of the present invention is to cope with an unknown structure substance thereby to identify the structure of a parent ion highly precisely and to derive a supposed structure.