Interleaved MS1 and MS2 Scans for High-Resolution Mass Spectrometry Quantification
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Solution Overview
Problem
Existing data-independent analysis (DIA) techniques in mass spectrometry face challenges in accurately identifying and quantifying proteins due to high molecular weights and complex mixtures, requiring high MS/MS scan speed and wide windows, which is not optimal for high-resolution mass analyzers and involves costly and time-consuming spectral library creation.
Innovation Solution
A DIA method utilizing an orbital trapping mass analyzer for high-resolution MS1 scans to identify and quantify precursor ions, with interleaved MS2 scans at lower resolution for validation, reducing the need for frequent MS2 sampling and allowing for improved resolution and sensitivity in the MS1 domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high MS/MS scan speed and wide windows are used in DIA, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The patent segments the MS1 and MS2 scanning into distinct phases with different resolution settings. MS1 scans are performed at high resolution for accurate precursor identification and quantitation, while MS2 scans are performed at lower resolution for validation. This segmentation allows each scanning phase to be optimized independently, resolving the contradiction between scan speed and measurement precision.
2Reliability
If frequent MS2 sampling is performed, then reliability is improved, but loss of time increases
Solution Approach 1:
The patent introduces MS1 domain analysis as an intermediary step that performs the primary identification and quantitation function. MS2 scans are then used only for validation rather than primary identification. This intermediary approach reduces the frequency requirement of MS2 sampling while maintaining reliability, as MS1 provides continuous high-resolution data for quantitation.
3Measurement precision
If high resolution MS1 scans are used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies different quality levels (resolution settings) to different parts of the analysis process. High resolution is applied locally to MS1 scans where precise precursor identification and quantitation are needed, while lower resolution is applied to MS2 scans where validation is sufficient. This local quality approach maintains measurement precision where needed without requiring the mass analyzer to operate at high resolution continuously, thereby reducing overall device complexity requirements.
Data Source
AI summary
A data independent acquisition method of mass spectrometry for analysing a sample as it elutes from a chromatography system is disclosed. The method comprises selecting a precursor mass range, and performing a plurality of MS1 scans and sets of MS2 scans across the precursor mass range. Each of the MS1 scans uses a mass analyser operated at a first, relatively higher resolution, for identification and/or quantitation of the sample in the MS1 domain. The set of MS2 scans comprises performing MS2 scans of fragmented mass range segments performed with the mass analyser, operated at a second, relatively lower resolution. In the method, the MS1 scans are interleaved throughout the performing of the set of MS2 scans such that the MS1 scans provide a mass chromatogram of the sample. The ratio of the number of MS1 scans to sets of MS2 scans performed across the chromatographic peak width is at least 3:1.