Mass Spectrometer Product Ion Selection with Exclusion Ranges
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Solution Overview
Problem
Conventional methods for selecting product ions in multiple reaction monitoring (MRM) measurements do not consider the mass-to-charge ratio, leading to incorrect qualitative or quantitative determinations due to the inclusion of inappropriate ions, such as precursor ions or ions with altered valence, which can result in false detection of target compounds.
Innovation Solution
A mass spectrometric method that involves setting specific mass-to-charge ratios for non-selection ions and selecting product ions based on predefined criteria within exclusion ranges to exclude undesired ions, ensuring that only characteristic product ions are chosen for MRM transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If product ions are selected based solely on signal intensity without considering mass-to-charge ratio, then the ease of automatic MRM transition setting is improved, but the reliability of compound identification deteriorates due to inclusion of non-characteristic ions
Solution Approach 1:
The patent applies parameter changes by introducing mass-to-charge ratio as an additional selection criterion alongside signal intensity. The system automatically filters product ions based on both intensity thresholds and m/z ratio matching, ensuring that only characteristic product ions corresponding to the precursor ion are selected for MRM transitions, thereby maintaining identification reliability while preserving automation.
2Quantity of substance
If precursor ions are not excluded from product ion selection, then the quantity of selected product ions is increased, but the measurement precision deteriorates due to false detection of target compounds
Solution Approach 1:
The patent extracts and removes precursor ions from the product ion spectrum before selection. By identifying and excluding ions with the same mass-to-charge ratio as the precursor ion, the system prevents false detection and ensures that only genuine product ions resulting from fragmentation are selected, thereby improving measurement precision while maintaining an adequate number of product ions for quantitative analysis.
3Manufacturing precision
If manual setting of MRM transitions is performed, then the manufacturing precision of transition selection is improved, but the productivity of analysis preparation deteriorates
Solution Approach 1:
The patent implements self-service by enabling the system to automatically perform MRM transition selection based on predefined criteria including signal intensity thresholds and mass-to-charge ratio matching. The automated process independently identifies characteristic product ions and generates MRM transitions without requiring manual intervention, thereby maintaining high selection accuracy while significantly improving analysis preparation productivity.
4Adaptability or versatility
If ions with altered valence are included in product ion selection, then the adaptability of ion selection is improved, but the object-affected harmful factors increase due to incorrect qualitative determination
Solution Approach 1:
The patent applies parameter changes by monitoring and filtering ions based on their mass-to-charge ratio characteristics. The system identifies and excludes ions with altered valence by comparing their m/z ratios against expected fragmentation patterns, thereby preventing false detections while maintaining the ability to adaptively select genuine product ions across different compound types.
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 allows for the accurate selection of product ions suited for qualitative and quantitative determinations, reducing errors by excluding non-characteristic ions and ensuring precise MRM transitions, thereby improving the reliability of compound identification and quantification.
Implementation Method 1
Collision-induced dissociation (CID) gas such as argon is supplied into the collision cell, and the precursor ions collide with the CID gas in the collision cell, so that precursor ions are fragmented and various product ions are generated.
Data Source
AI summary
In a mass spectrometric method of the invention, a mass spectrometer (2) is used having a mass separation unit (231, 234) before and after a collision cell (232) for fragmenting ions. When a product ion corresponding to a precursor ion set for a sample is selected by performing product ion scan with respect to the precursor ion, an exclusion range of mass-to-charge ratios is set based on information on non-selection ions input by a user, and a product ion that satisfies a predefined criterion is selected within a range of mass-to-charge ratios excluding the exclusion range in a product ion spectrum. According to the mass spectrometric method of the invention, product ions suited for measurement on a target compound can be selected.