Ion Trap Mass Spectrometry Repeated Dissociation Ejection
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Solution Overview
Problem
Ion trap mass spectrometers using dissociation techniques with low precursor-ion dissociation efficiency, such as HAD, ETD, and ECD, face challenges in achieving high detection sensitivity and signal-to-noise ratio due to low product ion generation, leading to decreased detection sensitivity and increased sample consumption.
Innovation Solution
A method involving repeated ion-dissociation and ejection operations in an ion trap mass spectrometer, where ions with lower mass-to-charge ratios than the target ion are selectively ejected during a mass scan, allowing for multiple dissociation and detection cycles without wasting the target ion, thereby enhancing detection sensitivity and signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low-efficiency dissociation techniques (HAD, ETD, ECD) are used, then structural information can be obtained, but detection sensitivity and signal-to-noise ratio decrease due to low product ion generation
Solution Approach 1:
The patent applies continuous accumulation of product ions generated through repeated dissociation cycles. Instead of single-shot dissociation, the system continuously generates and accumulates product ions over multiple cycles, transforming a low-efficiency process into a high-yield process through temporal integration and continuous action.
2Measurement precision
If low-efficiency dissociation techniques are used, then specific structural information can be acquired, but sample consumption increases
Solution Approach 1:
The patent recovers precursor ions that remain after each dissociation cycle by accumulating them for subsequent dissociation attempts. Instead of discarding undissociated ions, the system retains and reuses them across multiple cycles, significantly reducing the total sample quantity required to achieve sufficient product ion signals.
3Ease of operation
If conventional single-cycle dissociation is used, then analysis is simple, but detection sensitivity is insufficient with low-efficiency techniques
Solution Approach 1:
The patent employs periodic dissociation cycles where the ion trap repeatedly undergoes dissociation-accumulation-ejection sequences. This periodic operation allows the system to maintain simplicity in individual cycles while achieving high detection sensitivity through the cumulative effect of multiple cycles, with automatic control managing the repetition.
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 enables the acquisition of high-sensitivity mass spectra even with low-efficiency dissociation techniques, reducing sample usage and improving detection sensitivity and signal-to-noise ratio, while maintaining the target ion within the trap for multiple analyses.
Implementation Method 1
an ion trap capable of capturing ions by the effect of a radio-frequency electric field
Implementation Method 2
the behavior of the ions captured within the inner space of the ion trap can be expressed by the Mathieu equation
Implementation Method 3
create a radio-frequency quadrupole electric field within the inner space of the ion trap and capture ions by the effect of this electric field
Data Source
AI summary
After various ions of sample origin have been captured within an ion trap, unnecessary ions other than a target ion having a specific m/z are ejected from the ion trap (S1, S2). Subsequently, an operation for dissociating the target ion within the ion trap by hydrogen radical dissociation (HAD), and an operation for sequentially ejecting the thereby generated product ions by resonance excitation from the low m/z side to a point located immediately before the m/z of the target ion, are repeated multiple times (S3-S7). The ions ejected by resonance excitation are detected with a detector to acquire MS/MS spectrum data, and the data obtained by performing the ejection by resonance excitation multiple times are accumulated to create the final MS/MS spectrum (S5, S8).