Ion Guide Charge Reduction for Single-m/z Precursor Accumulation
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Solution Overview
Problem
Conventional mass spectrometry methods face reduced sensitivity due to the selection of only one precursor ion, leading to the loss of ion current from other precursor ions with different charge states, and existing ion parking techniques are complex and prone to fragmentation and saturation issues.
Innovation Solution
An ion guide device is used to apply an AC voltage and a DC voltage, creating a pseudopotential that traps and charge-reduces precursor ions with different m/z values, allowing them to be accumulated and transmitted at a single m/z value, thereby increasing sensitivity and preventing fragmentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only one precursor ion is selected for analysis using a quadrupole ion filter, then the mass spectrometry measurement can be performed with a specific m/z value, but the sensitivity is reduced due to loss of ion current from other precursor ions with different charge states
Solution Approach 1:
The patent applies a pseudopotential field in advance to trap precursor ions with different charge states before mass analysis. This preliminary trapping action allows multiple precursor ions to be accumulated and then selectively transmitted, converting the ion current loss problem into a solvable state by preparing the ions beforehand for controlled transmission.
Solution Approach 2:
The patent uses periodic modulation of the pseudopotential field to alternately trap and transmit precursor ions. By periodically adjusting the field parameters, the system can accumulate ions during one phase and transmit selected ions during another phase, thereby recovering ion current that would otherwise be lost while maintaining precise m/z selection.
2Quantity of substance
If ion parking techniques are used to accumulate multiple precursor ions, then the sensitivity can be improved, but the device complexity increases and fragmentation and saturation issues occur
Solution Approach 1:
The patent changes the parameters of the pseudopotential field (amplitude, frequency, phase) to control the trapping and transmission of precursor ions. By dynamically adjusting these parameters, the system can accumulate multiple precursor ions without requiring complex structural modifications, thereby improving sensitivity while controlling device complexity through parameter optimization rather than structural complexity.
3Quantity of substance
If precursor ions are accumulated for extended periods to increase sensitivity, then more ions can be detected, but fragmentation and saturation issues arise
Solution Approach 1:
The patent implements continuous transmission of accumulated precursor ions through the pseudopotential field rather than prolonged static accumulation. This continuous action allows ions to be steadily transmitted to the detector without extended停留 that would cause fragmentation or saturation, maintaining ion integrity while still achieving high sensitivity through continuous ion flow.
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 enhances the sensitivity of mass spectrometry by continuously accumulating and transmitting precursor ions at a single m/z value, improving the detection of multiple precursor ions and reducing the risk of fragmentation, while maintaining high m/z values for analysis.
Implementation Method 1
an AC voltage and a DC voltage are applied on electrodes of the ion guide device that creates a pseudopotential to trap the received two or more precursor ions
Implementation Method 2
causes the trapped two or more precursor ions to be charge reduced by the received charge reducing reagent so that their m/z values increase to a single m/z value above the threshold m/z
Data Source
AI summary
An ion source ionizes a compound, producing precursor ions with different m/z values. A reagent source supplies charge reducing reagent. An ion guide is positioned between a mass filter and both the ion source and the reagent source. The ion guide applies an AC voltage and DC voltage to its electrodes that creates a pseudopotential to trap the precursor ions in the ion guide below a threshold m/z. This AC voltage, in turn, causes the trapped precursor ions to be charge reduced by the reagent so that m/z values of the trapped precursor ions increase to a single m/z value above the threshold m/z. The ion guide applies the DC voltage to its electrodes relative to a DC voltage applied to electrodes of the mass filter that causes the precursor ions with m/z values increased to the single m/z value to be continuously transmitted to the mass filter.