Mass Spectrometer Collision Cell Periodic Switching
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Solution Overview
Problem
Conventional mass spectrometry methods, such as triple quadrupole and quadrupole-Time of Flight mass spectrometers, suffer from low duty cycles when performing parent or precursor ion scanning and obtaining fragment or daughter ion spectra, making them unsuitable for real-time data analysis in applications like on-line chromatography.
Innovation Solution
A method involving a collision, fragmentation, or reaction device that operates in alternating modes to record mass spectral data, allowing for the determination of accurate mass-to-charge ratios and the identification of fragment or product ions within a specific decimal mass-to-charge ratio window, enhancing the duty cycle and efficiency of mass spectrometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional mass spectrometry methods (triple quadrupole or quadrupole-ToF) are used to perform parent ion scanning and obtain fragment spectra, then the analysis of complex mixtures is enabled, but the duty cycle drops to 0.05-0.1% making real-time chromatography analysis unsuitable
Solution Approach 1:
The collision cell operates in periodic alternating modes between high collision energy (producing fragment ions) and low collision energy (transmitting parent ions), with each mode lasting approximately the same duration. This periodic switching enables the system to capture both fragment ion spectra and parent ion information within each cycle, achieving a duty cycle of at least 50% while maintaining the capability to analyze complex mixtures through tandem mass spectrometry.
2Measurement precision
If the collision cell operates continuously at high collision energy to produce fragment ions for spectral analysis, then fragment spectra can be obtained, but the duty cycle for detecting parent ions drops to around 0.1%
Solution Approach 1:
The collision cell switches periodically between high collision energy mode (for fragment ion production and spectral analysis) and low collision energy mode (for parent ion transmission and detection). This periodic operation ensures that both fragment spectra and parent ion signals are captured in alternating time windows within each cycle, resolving the contradiction between obtaining precise fragment spectral data and maintaining high parent ion detection duty cycle.
Solution Approach 2:
During the low collision energy phase, parent ions are transmitted through the collision cell without significant fragmentation, preparing them for subsequent detection. This preliminary transmission of intact parent ions before the high energy fragmentation phase ensures that parent ion signals are captured with high duty cycle, while the subsequent high energy phase provides the necessary fragment spectral information.
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 significantly improves the duty cycle and efficiency of mass spectrometry, enabling more effective analysis of complex mixtures and real-time data processing, particularly in chromatography applications.
Implementation Method 1
The ions are then fragmented by collisions with neutral gas molecules to yield daughter (or 'product') ions
Implementation Method 2
an orthogonal acceleration Time of Flight mass analyser
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A mass spectrometer comprising a collision, fragmentation or reaction cell (4) is disclosed. The collision, fragmentation or reaction cell (4) is repeatedly switched back and forth between a high fragmentation mode of operation and a low fragmentation mode of operation. Mass spectral data sets are obtained in both modes of operation. A decimal mass filter is applied to one or both sets of data. In particular, fragment ions or metabolites related to a parent or precursor ion of interest are identified on the basis of having a decimal mass which is similar to that of the parent or precursor ion of interest.