Scanning SWATH Precursor-Product Ion Pairing Under Overlap
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In scanning SWATH data, identifying precursor ions responsible for producing product ions is challenging due to lack of precursor ion information and interference from multiple precursor ions within the same mass selection window, leading to difficulties in correlating product ions to their corresponding precursors.
Innovation Solution
A system and method that utilize overlapping precursor ion mass selection windows to generate product ion spectra, with a processor creating a matrix multiplication equation to solve for the precursor ion intensities based on the intensity traces of selected product ions, employing numerical methods like non-negative least squares to accurately determine the contributing precursor ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a larger precursor ion mass selection window is used to scan the mass range, then the productivity of data collection is improved, but the measurement precision of precursor ion identification deteriorates due to interference from multiple precursor ions
Solution Approach 1:
The patent segments the contribution of each precursor ion to the product ion signal by using the derivative trace to identify inflection points that correspond to individual precursor ions within the mass selection window. This allows the system to deconvolute the combined signal into discrete precursor ion contributions, resolving the identification accuracy issue while maintaining the benefits of larger mass selection windows for productivity.
Solution Approach 2:
The patent introduces a new dimension of analysis by taking the derivative of the product ion intensity with respect to precursor ion mass. This derivative trace provides additional information about the relationship between precursor and product ions, enabling accurate identification even when multiple precursors are present in the same mass selection window.
2Device complexity
If traditional SWATH acquisition with a fixed precursor ion mass selection window is used, then the device complexity is reduced, but the loss of information about precursor ion correlations increases
Solution Approach 1:
The patent performs a preliminary action by acquiring a precursor ion spectrum before the SWATH acquisition. This preliminary spectrum provides information about the precursor ions present in the sample, which is then used to guide the analysis of product ion signals and improve the correlation between precursors and products without adding significant device complexity.
Solution Approach 2:
The patent replaces the need for complex mechanical or operational modifications to the mass spectrometer by using mathematical processing of the existing data. The derivative calculation and inflection point analysis are performed computationally on the acquired SWATH data, preserving the simplicity of the acquisition method while recovering lost correlation information.
3Measurement precision
If scanning SWATH with overlapping precursor ion mass selection windows is implemented, then the measurement precision of precursor ion identification is improved, but the device complexity and data processing complexity increase
Solution Approach 1:
The patent extracts the key information needed for precursor ion identification by calculating the derivative of the product ion intensity with respect to precursor ion mass. This extraction process isolates the critical features (inflection points) from the complex overlapping data, simplifying the analysis while maintaining high identification accuracy.
Solution Approach 2:
The patent changes the parameter being analyzed from raw product ion intensity to the derivative of intensity with respect to mass. This parameter transformation converts the complex overlapping signals into a form where individual precursor ion contributions are more easily distinguished, improving measurement precision without requiring complex device modifications.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A system is disclosed for identifying a precursor ion of a product ion in a scanning DIA experiment. A precursor ion mass selection window is scanned across a precursor ion mass range of interest, producing a series of overlapping windows across the precursor ion mass range. Each overlapping window is fragmented and mass analyzed, producing a plurality of product ion spectra for the mass range. A product ion is selected from the spectra. Intensities for the selected product ion are retrieved for at least one scan across the mass range producing a trace of intensities versus precursor ion m/z. A matrix multiplication equation is created that describes how one or more precursor ions correspond to the trace for the selected product ion. The matrix multiplication equation is solved for one or more precursor ions corresponding to the selected product ion using a numerical method.