Chromatograph Mass Spectrometer Precursor Ion Exclusion

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Solution Overview

Problem

Chromatograph-mass spectrometers with automatic MS2 functions face challenges in performing MS2 analysis on a wide variety of components, particularly when multiple components with similar retention times elute close together, leading to repeated selection of precursor ions from the same compound, which can result in important components being overlooked or analyzed with reduced sensitivity due to isotopic variations.

Innovation Solution

A chromatograph-mass spectrometer with a selection condition setting means to define a mass/charge ratio range for excluding precursor ion selection, an analysis control means for repeated MS2 analysis, and a precursor selection means that excludes ions within a predetermined range after a certain number of analyses, ensuring diverse component analysis and preventing isotopic and adduct ion selection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If automatic MS2 analysis is performed by selecting precursor ions based on signal strength criteria, then MS2 analysis can be performed in real-time, but the same component may be analyzed repeatedly while other important components are overlooked

Engineering Contradiction:

Improvereal-time MS2 analysis capabilityVSAvoidcoverage of diverse components

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The system performs preliminary actions by establishing exclusion criteria and mass difference thresholds before analysis begins. When a precursor ion is selected for MS2 analysis, the system proactively excludes ions with masses within a predetermined difference range from future selection, preventing repetitive analysis of the same component and its isotopes while maintaining real-time analysis capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the selection parameters dynamically by introducing a mass difference threshold parameter. Ions whose masses fall within the predetermined difference range of previously analyzed precursor ions are excluded from selection, thereby diversifying the components analyzed while maintaining real-time processing speed

Inventive Principle:

Principle #35Parameter changes

2Speed

If the number of precursor ions selected for MS2 analysis is limited by time constraints, then real-time analysis is maintained, but important components may be overlooked when multiple components elute close together

Engineering Contradiction:

Improvereal-time analysis speedVSAvoiddetection accuracy of important components

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system implements feedback by continuously monitoring which ions have been selected for MS2 analysis and using this information to influence future selections. The exclusion mechanism provides feedback that prevents re-selection of recently analyzed ions and their isotopes, ensuring that limited analysis time is distributed across diverse components rather than concentrated on repetitive analyses

Inventive Principle:

Principle #23Feedback

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 enhances the likelihood of obtaining MS2 analysis results for a broader range of compounds by avoiding repeated selection of ions from identical components and increasing the chances of detecting different compounds, thereby reducing the risk of overlooking important components and improving analysis sensitivity.

Implementation Method 1

a mass spectrometry unit that is capable of selectably performing a MS2 analysis on ions derived from the specimen components

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 2

an ion having a specific mass/charge ratio (m/z) is selected as a precursor ion from among various ions that are derived from the component being analyzed

Methodology Applied

Scientific EffectMass spectrometry:

Implementation Method 3

The precursor ion is dissociated by collision induced dissociation (CID), and the product ions that are generated are subjected to mass spectroscopy to produce a MS/MS (=MS2) spectrum

Methodology Applied

Scientific EffectCollision induced dissociation:

Data Source

PatentUS9431224B2Chromatograph mass spectrometer

Publication Date: 2016.08.30 SHIMADZU CORP

AI summary

When performing an automatic MS2 analysis on a specimen containing components that include elements whose abundance ratio of stable isotopes is close, to prevent the same component that includes isotopes of differing masses to be successively selected as a precursor ion and allow the MS2 analysis of various components whose retention time to elution is close. As precursor selection conditions, the user is allowed to set in advance the time period for automatic exclusion and a m/z range (−p, q) with respect to any m/z. When the analysis is performed, a precursor selection unit selects a precursor according to a predetermined selection condition for the MS spectrum that was obtained and repeats the MS2 analysis on the precursor ion (m/z=M) for the number of times that is set. Thereafter, for a specified automatic exclusion period, ions falling in a m/z range of M−p to M+q are excluded from selection as a precursor. Since ions that are derived from a component whose difference from the original component from which the ion whose m/z=M is derived is the isotopes will fall in the excluded m/z range, such ions are not used as a precursor ion.