Data-Dependent Acquisition Apex Identification via Phase Analysis
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Solution Overview
Problem
Current data-dependent acquisition methods in mass spectrometry often trigger MS/MS analysis at suboptimal times, leading to lower quality spectra due to background contaminants and redundant data collection, especially when using intensity-based triggering, which can mistakenly identify noise spikes as compound peaks.
Innovation Solution
A method that uses a correlation technique to select eluting m/z peaks of interest from a weighted mass spectrum and phase analysis to identify the apex of chromatographic peaks, combining these methods to improve data-dependent peak selection and reduce random peak selection by over 65%, thereby enhancing the accuracy and timing of MS/MS analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct intensity-based triggering is used to select peaks for MS/MS analysis, then the acquisition process is simple and fast, but the triggering occurs at suboptimal times leading to lower quality spectra with more background contaminants
Solution Approach 1:
The patent performs preliminary analysis of the chromatographic peak shape and phase information before triggering MS/MS acquisition. By predicting the apex position and timing in advance using the phase-sensitive extraction method, the system can trigger at the optimal moment rather than relying on simple intensity thresholds, thus improving spectrum quality without sacrificing acquisition speed.
2Loss of time
If MS/MS analysis is triggered at the beginning of chromatographic peak elution, then acquisition time is reduced, but the spectra contain higher percentage of background contaminants and limited sample ions
Solution Approach 1:
The system continuously monitors the phase information and intensity changes during peak elution, using this feedback to dynamically adjust the triggering decision. The phase-sensitive extraction provides real-time information about the peak position and shape, allowing the system to trigger MS/MS at the optimal moment when signal-to-noise ratio is maximized, rather than at a fixed early time point.
3Extent of automation
If intensity-based triggering is used with high baseline, then all masses are triggered causing redundant data collection, but selective triggering is needed to avoid redundancy
Solution Approach 1:
The patent applies local quality analysis by examining the phase information and intensity characteristics at each specific m/z value independently. Instead of applying a global intensity threshold to all masses, the system evaluates each peak's phase angle and chromatographic behavior locally, allowing selective triggering only for peaks that meet the criteria, thus avoiding redundant acquisitions while maintaining automation.
4Measurement precision
If phase analysis and correlation techniques are implemented to accurately identify peak apex, then peak selection accuracy is improved, but the processing complexity increases
Solution Approach 1:
The patent replaces complex mechanical or computational peak detection methods with a phase-based analytical approach. By transforming the time-domain chromatographic data into frequency domain using phase-sensitive extraction, the system can identify peak apex positions more accurately through phase angle measurements, simplifying the overall processing while improving precision.
Data Source
AI summary
A method of analyzing data from a mass spectrometer provides data-dependent acquisition. An extracted ion chromatogram (XIC) is created for each m/z data point of mass spectral scans and the XIC for each m/z data point are correlated to a model function to obtain a XIC correlation value. A weighting function is applied to the XIC correlation value to obtain a current weighted intensity for each m/z point, which is used to reconstruct a weighted mass spectrum. The value or range of intensities of interest of the weighted intensity data or raw data is transformed from the time domain into the frequency domain, and the transformed data is used to make a real-time decision for the data-dependent acquisition. The data-dependent acquisition can be the performance of tandem mass spectrometry. A sample processing apparatus receives the sample and a computer readable medium provides instructions to the apparatus.