Tandem Mass Spectrometer Ion Store Design
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Solution Overview
Problem
Conventional tandem mass spectrometers with consecutive geometry face limitations due to high ion losses caused by low duty cycles and lack of flexibility in incorporating additional apparatus like ion sources, laser radiation, or electron sources, restricting their applicability and efficiency in mass analysis.
Innovation Solution
A mass spectrometer with a longitudinal axis design that includes an intermediate ion store allowing ions to travel forwards and backwards along the axis, enabling off-axis ejection to a mass analyzer, which enhances ion storage and processing capabilities, including fragmentation and reaction processes, thereby overcoming the limitations of previous designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional tandem mass spectrometer with consecutive geometry is used, then the mass analysis function is provided, but high ion losses occur due to low duty cycle
Solution Approach 1:
The ion store operates in periodic cycles, accumulating ions during one phase and ejecting them in synchronized pulses to the mass analyser during another phase. This periodic operation ensures that ion extraction, reaction cell processing, and mass analysis are temporally coordinated, eliminating idle time and maximizing the duty cycle while maintaining high ion transmission efficiency through the synchronized pulse ejection mechanism.
2Adaptability or versatility
If a consecutive geometry design is used, then installation of RF collision cell or trapping stage is enabled, but flexibility to incorporate additional apparatus such as ion sources, laser radiation, or electron sources is restricted
Solution Approach 1:
The ion store is positioned off the main longitudinal axis of the mass spectrometer, creating a spatial dimension that allows additional apparatus (ion sources, laser radiation, electron sources) to be incorporated at locations not constrained by the linear consecutive geometry. This dimensional shift enables versatile configuration of reaction cells and processing stages while maintaining efficient ion transport through the store's periodic ejection mechanism.
3Adaptability or versatility
If orthogonal pulsing is used to eject ions to the mass analyser, then the reaction cell design is flexible, but high ion losses occur due to low duty cycle
Solution Approach 1:
The ion store maintains continuous accumulation of ions from the reaction cell while synchronizing ejection pulses with the mass analyser's operational cycle. This continuous operation eliminates idle periods between ion batches, ensuring that the reaction cell continuously processes ions without interruption. The synchronized pulse ejection maintains optimal ion density for mass analysis while maximizing the utilization of the reaction cell, thereby reducing overall ion losses despite the orthogonal ejection geometry.
Data Source
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AI summary
This invention relates to a mass spectrometer including a reaction cell and to a method of using such a mass spectrometer. In particular, although not exclusively, this invention relates to a tandem mass spectrometer and to tandem mass spectrometry. The invention provides a method of mass spectrometry using a mass spectrometer having a longitudinal axis, comprising guiding ions to travel along the longitudinal axis of the mass spectrometer in a forwards direction to pass through an intermediate ion store and then to enter a reaction cell, to process the ions within the reaction cell, to eject the processed ions to travel back along the longitudinal axis to enter the intermediate ion store once more, and to eject one or more pulses of the processed ions in an off-axis direction to a mass analyser.