Chromatograph Mass Spectrometer MS/MS Acquisition
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Solution Overview
Problem
Current chromatograph mass spectrometers face challenges in achieving high-purity and exhaustive MS/MS spectra due to limitations in the number of precursor ions that can be analyzed simultaneously, leading to either low purity or low exhaustiveness in component detection.
Innovation Solution
A chromatograph mass spectrometer that combines a chromatograph with a tandem mass spectrometry section, using cyclic analysis cycles that include both data-independent and data-dependent acquisition methods to select and analyze precursor ions based on intensity information, allowing for high-purity and exhaustive MS/MS spectra acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of precursor ions for MS/MS analysis is increased to improve exhaustiveness, then more components can be detected, but the sampling period becomes excessively long and quantitative performance deteriorates
Solution Approach 1:
The mass-to-charge ratio range is divided into multiple narrow windows, and MS/MS analysis is performed sequentially for each window containing precursor ions. This segmentation allows comprehensive coverage of all components while maintaining a manageable number of simultaneous analyses, thus preserving quantitative performance.
Solution Approach 2:
The system performs preliminary scanning to identify windows containing precursor ions before conducting MS/MS analysis. This preliminary action enables the system to focus resources only on relevant mass ranges, improving exhaustiveness without excessively extending the sampling period.
2Measurement precision
If the mass-to-charge ratio range for precursor ion selection is narrowed to improve MS/MS spectrum purity, then product ions from single ion species are observed, but the number of detectable components is limited
Solution Approach 1:
The full mass-to-charge ratio range is segmented into multiple narrow windows, each analyzed separately for MS/MS. This ensures high spectral purity within each window while collectively covering the entire range to maintain analytical exhaustiveness.
Solution Approach 2:
The system performs MS/MS analysis on multiple windows that may overlap or extend beyond the most intense peaks, ensuring that no potential precursor ions are missed. This partial redundancy guarantees exhaustiveness while maintaining acceptable purity through the narrow window approach.
3Productivity
If data independent acquisition with wide windows is used to improve exhaustiveness, then all components can be analyzed, but MS/MS spectrum purity decreases due to mixed product ions
Solution Approach 1:
Instead of using wide windows as in traditional DIA, the system segments the mass-to-charge ratio range into multiple narrow windows. This segmentation maintains exhaustiveness by covering the entire range while improving purity by reducing the number of different precursor ions contributing to each MS/MS spectrum.
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 the acquisition of high-quality, high-purity MS/MS spectra with improved sensitivity and exhaustiveness, even for components with low abundance, while ensuring quantitative performance by optimizing the timing of MS/MS analysis.
Implementation Method 1
a quadrupole mass filter (26) and a collision cell (27)
Implementation Method 2
a quadrupole time-of-flight mass spectrometer (Q-TOF mass spectrometer), which uses a time-of-flight mass separator as the rear-stage mass separator
Implementation Method 3
an MS/MS analysis in which an ion or ions corresponding to the selected ion peak or peaks are designated as a precursor ion or ions is subsequently performed
Data Source
AI summary
In a chromatograph mass spectrometer having a measurement unit (1) including a chromatograph is combined with a tandem mass spectrometry section capable of an MS/MS analysis, a controller (40) performs chromatograph mass spectrometry by controlling the measurement unit so as to operate the tandem mass spectrometry section to cyclically perform analysis cycles, where each of the analysis cycles includes a first mass spectrometric analysis in which a measurement of ions is performed over a predetermined m/z range and an MS/MS analysis by DIA in which ions included within each of a plurality of windows formed by dividing the m/z range are designated as a precursor ion. A window selector (42, 43) selects, during an execution of an analysis cycle, a window among the plurality of windows for an MS/MS analysis by DDA which is irregularly performed in an ongoing analysis cycle, based on intensity information obtained for each of the plurality of windows from an MS/MS spectrum acquired by the MS/MS analysis by DIA. A precursor-ion determiner (44) determines a precursor ion corresponding to the window selected by the window selector in a mass spectrum acquired by the first mass spectrometric analysis in the ongoing analysis cycle, based on peak information included within the m/z range of the window. A data-dependent-acquisition condition setter (45) informs the controller of the precursor ion determined by the precursor-ion determiner, as the precursor ion for the MS/MS analysis by DDA which is irregularly performed in the ongoing analysis cycle.