Gas-phase Purification for Isobaric Tag Quantification

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Solution Overview

Problem

Isobaric tagging in mass spectrometry is limited by precursor interference, leading to inaccurate quantification and restricted dynamic range, especially in complex samples, due to co-isolation of interfering species with similar mass-to-charge ratios, which compresses measured ratios towards the median, thereby restricting its application to samples with lower complexity.

Innovation Solution

The method involves gas-phase purification by selectively changing the mass-to-charge ratios of precursor ions using proton-transfer ion-ion reactions (PTR) to separate and isolate ions, thereby eliminating interference and improving the accuracy of isobaric tag-based quantification by narrowing the isolation window and decoupling sequence and reporter ion generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If isobaric tagging is used for quantification, then multiplexed protein quantification capability is improved, but measurement precision deteriorates due to precursor interference and co-isolation of interfering species

Engineering Contradiction:

Improvemultiplexed protein quantification capabilityVSAvoidquantification accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the quantification process into two distinct stages: (1) precursor isolation and identification, and (2) reporter ion detection. By decoupling these stages through ion mobility separation, the method eliminates precursor interference from affecting quantification accuracy while maintaining multiplexed capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces ion mobility separation as an intermediary technique between precursor selection and reporter ion detection. This intermediary step separates ions based on their collisional cross-section, effectively removing interfering species with similar m/z ratios before they can contaminate the quantification signal.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If conventional precursor isolation is used, then isolation speed is improved, but manufacturing precision deteriorates due to co-isolation of interfering species with similar mass-to-charge ratios

Engineering Contradiction:

Improveisolation speedVSAvoidprecursor purity

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The patent adds ion mobility separation as an additional dimension of separation beyond traditional mass-to-charge ratio filtering. This fourth dimension (ion mobility) allows the system to resolve and separate interfering species that have identical or very similar m/z ratios, dramatically improving precursor purity without sacrificing isolation speed.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If wide isolation window is used, then productivity is improved by capturing more precursor ions, but measurement precision deteriorates due to increased interference from co-isolated species

Engineering Contradiction:

Improveprecursor ion capture efficiencyVSAvoidquantification accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent segments the isolation window into multiple narrow windows across different ion mobility drift times. Each narrow window captures a specific subset of precursor ions with high purity, and the results are combined to achieve both high productivity and high precision quantification.

Inventive Principle:

Principle #1Segmentation

4Measurement precision

If narrow isolation window is used, then measurement precision is improved by reducing interference, but productivity deteriorates due to reduced precursor ion capture

Engineering Contradiction:

Improvequantification accuracyVSAvoidprecursor ion capture efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent uses ion mobility separation to create an extended separation space that allows narrow m/z isolation windows to be combined with effective precursor capture. By separating ions in the ion mobility dimension, the system can use narrow mass windows for high precision while still capturing sufficient ions through the mobility separation process.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 significantly enhances the accuracy and dynamic range of isobaric tag-based quantification, allowing for large-scale, multiplexed protein quantification by effectively purifying precursor ions and reducing interference, making it suitable for complex samples that were previously challenging.

Implementation Method 1

The method involves gas-phase purification by selectively changing the mass-to-charge ratios of precursor ions using proton-transfer ion-ion reactions (PTR) to separate and isolate ions

Methodology Applied

Scientific EffectProton-transfer ion-ion reactions: Ion Repulsion/Attraction

Data Source

PatentUS10852306B2Gas-phase purification for accurate isobaric tag-based quantification

Publication Date: 2020.12.01 WISCONSIN ALUMNI RES FOUND

AI summary

Described herein are mass spectrometry systems and methods which improve the accuracy of isobaric tag-based quantification by alleviating the pervasive problem of precursor interference and co-isolation of impurities through gas-phase purification. During the gas-phase purification, the mass-to-charge ratios of precursor ions within at least a selected range are selectively changed allowing ions having similar unmodified mass-to-charge ratios to be separated before further isolation, fragmentation or analysis.