Dual Waveform Ion Isolation in RF Traps

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Solution Overview

Problem

Ion-ion interactions in mass spectrometry complicate the isolation of precursor ions, leading to reduced efficiency due to shifts in oscillation frequency and increased ion cloud size, making it difficult to isolate precursor ions in the presence of large ion populations.

Innovation Solution

A mass spectrometer with a radio frequency ion trap and a controller that supplies specific isolation waveforms with wide and narrow notches at targeted mass-to-charge ratios, where the q values of these notches differ by a factor of no greater than 2, to effectively isolate precursor ions from an ion population.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single isolation waveform with a narrow notch is used to isolate precursor ions, then the isolation precision is improved, but the isolation efficiency decreases due to ion-ion interactions shifting oscillation frequencies

Engineering Contradiction:

Improveisolation precisionVSAvoidisolation efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent divides the isolation waveform into two distinct components: a first isolation waveform with a wide notch and a second isolation waveform with a narrow notch. The wide notch waveform first captures the majority of precursor ions across a broader frequency range, while the narrow notch waveform subsequently refines the isolation to achieve high precision. This segmentation allows the system to overcome ion-ion interaction effects that would otherwise cause frequency shifts and reduce isolation efficiency.

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If the ion population in the trap is increased to improve signal intensity, then the sensitivity is improved, but the ion-ion interactions increase causing frequency shifts and reduced isolation efficiency

Engineering Contradiction:

Improveion populationVSAvoidisolation efficiency

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies the first isolation waveform with the wide notch before applying the second isolation waveform with the narrow notch. This preliminary action allows the wide notch to capture ions across a broader frequency range first, establishing a foundation that is then refined by the narrow notch waveform. This sequential approach ensures that even with large ion populations causing frequency shifts, the isolation remains effective because the wide notch accommodates the frequency variations.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If a wide notch waveform is used to capture ions across a broad frequency range, then the isolation efficiency is improved, but the isolation precision decreases

Engineering Contradiction:

Improveisolation efficiencyVSAvoidisolation precision

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent segments the isolation process into two distinct waveform applications: first a wide notch waveform to capture ions efficiently across a broad frequency range, then a narrow notch waveform to refine the isolation and achieve high precision. This segmentation allows each waveform to optimize for its specific function without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs dynamic switching between two different isolation waveforms with different notch widths. The system transitions from a wide notch configuration optimized for efficiency to a narrow notch configuration optimized for precision, allowing the isolation parameters to adapt dynamically to the needs of different stages in the isolation process.

Inventive Principle:

Principle #15Dynamics

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 improves the isolation efficiency of precursor ions by refining the ion trap's waveform strategy, maintaining sensitivity and rectangular impulse response even at higher ion densities, thereby enhancing the precision and accuracy of mass spectrometry analysis.

Implementation Method 1

a radio frequency ion trap and a controller

Methodology Applied

Scientific EffectElectromagnetic field: Electric Field

Implementation Method 2

cause an ion population to be injected into the radio frequency ion trap

Methodology Applied

Scientific EffectIon trapping:

Implementation Method 3

ion-ion interactions can shift the oscillation frequency of ions in the trap to lower frequencies

Methodology Applied

Scientific EffectIon oscillation frequency shift:

Implementation Method 4

supply a first isolation waveform to the radio frequency ion trap for a first duration, and supply a second isolation waveform to the radio frequency ion trap for a second duration

Methodology Applied

Scientific EffectWaveform isolation:

Data Source

PatentUS9818595B2Systems and methods for ion isolation using a dual waveform

Publication Date: 2017.11.14 THERMO FINNIGAN LLC

AI summary

A mass spectrometer includes a radio frequency ion trap; and a controller. The controller is configured to cause an ion population to be injected into the radio frequency ion trap; supply a first isolation waveform to the radio frequency ion trap for a first duration, and supply a second isolation waveform to the radio frequency ion trap for a second duration. The first isolation waveform has at least a first wide notch at a first mass-to-charge ratio, and the second isolation waveform has at least a first narrow notch at the first mass-to-charge ratio. The first and second isolation waveforms are effective to isolate one or more precursor ions from the ion population.