Mass Spectrometer Automated Precursor Ion Selection
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Solution Overview
Problem
Conventional MSn analysis methods struggle to automatically select an appropriate precursor ion for multi-stage dissociation in metabolite analysis, relying heavily on operator experience and skill, which can lead to incorrect selection and inefficient structural analysis.
Innovation Solution
A mass spectrometer system that creates MSm−1 spectra and mass-difference spectra for two components, extracts common and complementary peaks, and designates these peaks as precursor ions for subsequent dissociation stages, automating the selection process and prioritizing ions likely to provide structural information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional automatic precursor ion selection methods are used, then the selection process is automated, but the reliability of selecting the correct ion corresponding to the site of metabolism is insufficient
Solution Approach 1:
The patent segments the precursor ion selection process into multiple independent evaluation criteria: (1) signal intensity threshold filtering, (2) mass-to-charge ratio ordering, and (3) metabolite-specific site of metabolism identification. This segmentation allows each criterion to be evaluated separately and combined to achieve both automation and reliability in selecting the correct precursor ion.
2Reliability
If operator visual inspection is used to select precursor ions, then the reliability of selection improves, but the productivity and efficiency of the analysis process deteriorates
Solution Approach 1:
The system implements self-service by enabling automatic precursor ion selection through programmed algorithms that evaluate multiple criteria (signal intensity, m/z ordering, and site of metabolism characteristics) without requiring operator intervention. This allows the system to perform high-throughput automated analysis while maintaining reliable selection accuracy, eliminating the trade-off between manual inspection quality and processing speed.
3Measurement precision
If multi-stage dissociation is performed to analyze complex metabolites, then the measurement precision of structural analysis improves, but the complexity of the analysis process increases
Solution Approach 1:
The patent applies preliminary action by performing signal intensity evaluation and candidate ion filtering at earlier stages of the MSn analysis process. This preliminary sorting and selection of candidate precursor ions based on intensity thresholds and m/z ordering simplifies subsequent multi-stage dissociation operations, reducing the complexity burden while maintaining high structural analysis precision through systematic multi-stage breakdown.
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 approach enables efficient and accurate automatic selection of precursor ions, reducing operator dependency and improving the efficiency of structural analysis by focusing on specific structural differences, particularly in metabolite analysis.
Implementation Method 1
the selected precursor ion is dissociated by a collision induced dissociation (CID) process to produce product ions
Data Source
AI summary
A product ion spectrum is created on the basis of MS2 analysis data respectively obtained for a parent compound and a metabolite (S1 and S2). Additionally, a neutral loss spectrum, in which the mass of each product ion is replaced with a mass difference between the mass of the product ion and that of a precursor ion, is created (S3). Then, a common peak having the same mass on the neutral loss spectrums of both the parent compound and the metabolite is extracted (S4), and a complementary peak appearing on the product ion spectrum of the metabolite is extracted (S5); this peak appears at a position corresponding to the difference between the mass of the common peak and that of the precursor ion. The ion corresponding to the complementary peak is designated as a precursor ion for the next MS3 analysis (S6), and this MS3 analysis is performed (S7). By a dissociation operation, if a portion common to the parent compound and the metabolite is desorbed in the form of a neutral molecule while a different portion remains in the form of an ion, an MS3 analysis in which the ion of the different portion is used as the precursor ion is performed to obtain structural information of a site of metabolism.