Quadrupole-Ion Trap Tandem MS Ion Storage for Higher Duty Cycle
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Solution Overview
Problem
Quadrupole ion traps have limited ion storage capacity, leading to space charge effects, mass shifts, and analysis result distortion, with a low duty cycle and decreased sensitivity due to ion waste during analysis.
Innovation Solution
Implement a novel ion storage system with two ion guides (I-type and II-type square quadrupoles) and a specific time sequence control method to operate in ion storage and transmission modes, allowing continuous ion storage during analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If more ions are injected into the ion trap, then ion storage capacity is improved, but space charge effect occurs leading to mass shift and analysis result distortion
Solution Approach 1:
The system divides the ion storage function into two separate components: the ion guide (for accumulation) and the ion trap (for analysis). This segmentation allows the ion guide to hold large numbers of ions without affecting the mass accuracy in the ion trap, resolving the contradiction between storage capacity and measurement precision.
Solution Approach 2:
The ion guide acts as an intermediary component between the ion source and the ion trap. It accumulates ions and releases them in controlled amounts to the ion trap, preventing space charge effects while maintaining high overall storage capacity. This mediator role resolves the contradiction by decoupling storage from analysis.
2Quantity of substance
If ion storage is performed in the ion trap, then ion storage capacity is improved, but ion analysis cannot be performed simultaneously resulting in low duty cycle
Solution Approach 1:
The system separates storage and analysis functions into different components: the ion guide handles storage while the ion trap handles analysis. This allows both functions to operate simultaneously without interfering with each other, eliminating the duty cycle limitation.
Solution Approach 2:
The ion guide continuously accumulates ions during the entire analysis cycle, including when the ion trap is performing MSn experiments. This continuous storage action ensures that ions are always available for analysis, achieving 100% duty cycle and resolving the contradiction between storage capacity and productivity.
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
Improves ion storage capacity and duty cycle, enhancing sensitivity and reducing detection limits by utilizing ion guides for continuous storage during analysis.
Implementation Method 1
For the ion trap mass analyzer, certain radio frequency voltage and direct current voltage are applied to form a quadrupole field for trapping ions
Implementation Method 2
the first ion guide is an I-type square quadrupole for collisional focusing and transmission of ions in second-stage vacuum
Implementation Method 3
the electrodes are driven by radio frequency voltages, and the radio frequency voltages of the adjacent electrodes are opposite in polarity
Data Source
AI summary
The present invention relates to the technical field of mass spectra. Disclosed are a novel ion storage system and method based on a quadrupole-ion trap tandem mass spectrometry. The system sequentially comprises a heating capillary, a tube lens, a skimmer, a first ion guide, a second ion guide, a quadrupole mass analyzer, an ion trap mass analyzer, and a detector; a first lens is provided between the first ion guide and the second ion guide; a second lens and a third lens are provided between the second ion guide and the quadrupole mass analyzer, wherein operation modes of the first ion guide and the second ion guide comprise an ion transmission mode and an ion storage mode. Compared with conventional time sequence control methods, more ions are stored during the same time according to the present invention, thereby improving the sensitivity of the instrument.