Mass Analysis Data Structure Deduction via Fragment Ion Comparison
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Solution Overview
Problem
Current mass analysis methods, such as MS/MS, face challenges in deducing the structure of unknown substances, especially when they have complex structures or are not registered in databases, as they often require multiple dissociation steps and struggle to handle variations in molecular weights and compositions, like those found in agrichemicals and pharmaceutical compounds.
Innovation Solution
A method involving MSn analysis where precursor ions are dissociated into fragment ions multiple times, followed by comparing mass spectra with known substances to identify common fragment ion peaks, deducing partial structures, and using structural change patterns to create candidate structures for unknown substances, thereby improving analysis efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pattern matching method using a mass spectrum database is used to deduce the structure of an unknown substance, then the analysis can be performed quickly for registered compounds, but the method fails when the unknown substance is not registered in the database
Solution Approach 1:
The patent segments the mass spectrum into individual fragment ion peaks and further segments the molecular structure into partial structures. By comparing individual fragment ion peaks between unknown and known substances, the method identifies matching peaks and corresponds them to specific partial structures, enabling structure deduction even when the complete molecule is not in the database.
Solution Approach 2:
The patent introduces fragment ion peaks as an intermediary between the unknown substance and the database of known substances. Instead of directly comparing complete mass spectra, the method uses fragment ion peaks as intermediate elements that can be matched between unknown and known compounds, facilitating structure deduction for unregistered substances.
2Measurement precision
If multiple dissociation steps (MSn analysis) are performed to analyze complex substances, then the structural information obtained is more detailed, but the analysis time and complexity increase significantly
Solution Approach 1:
The patent extracts key information from the complex MSn analysis by focusing specifically on fragment ion peaks rather than processing the entire complex mass spectrum. By extracting and comparing only the relevant fragment ion peaks between unknown and known substances, the method reduces the amount of data to be processed while retaining the essential structural information needed for deduction.
3Adaptability or versatility
If a large mass spectrum database containing all possible compounds is created, then all unknown substances can be identified, but the database size and storage requirements become impractical
Solution Approach 1:
The patent segments both the mass spectra and molecular structures into smaller units (fragment ion peaks and partial structures). This segmentation allows the database to store information in a more compact form, where a single known compound's fragment patterns can be reused to help identify multiple related unknown compounds, reducing the overall database size requirement.
Solution Approach 2:
The patent uses partial matching of fragment ion peaks rather than requiring complete spectrum matching. By accepting partial matches between fragment ions of unknown and known substances, the method can identify unregistered compounds without needing exhaustive database coverage, thereby reducing database size requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the deduction of unknown substance structures even if they are not registered in databases, by identifying common fragment ion peaks and utilizing structural change patterns, thus enhancing analysis efficiency and accuracy.
Implementation Method 1
an ion having a specific mass-to-charge ratio (m/z) is first separated from the material to be analyzed
Implementation Method 2
the precursor ion thus separated is broken into fragment ions by a collision-induced dissociation (CID) process
Data Source
AI summary
The present invention provides a method and an apparatus for analyzing mass analysis data for easily deducing the structure of an unknown substance, based on data obtained by an MSn analysis. First, the structural formula of a precursor ion of the unknown substance is deduced based on the mass-to-charge ratio of the precursor ion (Step S12), and candidate structures which have the same compositional formula as the compositional formula deduced in Step S12, by combining the structure of the known substance and known structural change patterns (Step S14). Next, fragment ion peaks expected to appear from the candidate structures are deduced (Step S15), and based on the expected fragment ion peaks, the candidate structures are ranked in the order of probability (Step S16). Then, by comparing a mass spectrum of the known substance and that of the unknown substance, a common fragment ion peak is searched. (Step S19). If a common peak exists, assuming that a partial structure of the known substance corresponding to the peak is included also in the unknown substance, the candidate structures are narrowed down based on information on the partial structure (Step S21).