Tandem Mass Spectrometry Ion Segmentation for Overcrowding
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Solution Overview
Problem
Current tandem mass spectrometry techniques face limitations in analyzing complex mixtures due to restricted precursor selection, low resolution, and overcrowding of spectra, particularly in high-energy fragmentation modes, which hinders the identification of precursor and fragment ions in complex samples like proteomics and environmental analysis.
Innovation Solution
The method involves segmenting a broad mass-to-charge ratio ion stream into segments with independently selected fragmentation levels, allowing for high-resolution analysis of both fragmented and unfragmented ions, which reduces peak overcrowding and improves mass accuracy by optimizing the distribution of precursor and fragment ions across the spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-energy fragmentation is used to increase throughput, then analysis speed improves, but spectral overcrowding increases and resolution deteriorates
Solution Approach 1:
The patent segments the ion beam into multiple packets based on m/z ratio using a scanning device. Each packet is fragmented independently, allowing control over fragmentation degree. This segmentation prevents spectral overcrowding by distributing fragment ions across different time windows while maintaining high throughput through parallel processing of multiple packets.
Solution Approach 2:
The patent employs dynamic adjustment of fragmentation energy and timing for different ion packets. The scanning device continuously varies the mass range of packets, and fragmentation conditions are dynamically optimized for each packet. This dynamic approach allows high-energy fragmentation when needed while avoiding overcrowding, resolving the contradiction between speed and resolution.
2Device complexity
If traditional data-dependent selection is used to reduce spectral complexity, then peak overcrowding decreases, but the number of detectable precursors is limited
Solution Approach 1:
The ion beam is segmented into multiple packets that are processed in sequence. Each packet contains a specific m/z range, allowing systematic exploration of the full mass spectrum. This segmentation enables detection of many more precursors than traditional single-precursor methods while keeping each individual spectrum relatively simple through controlled fragmentation of selected packets.
Solution Approach 2:
The scanning device performs periodic scanning through different mass ranges, systematically cycling through various m/z regions. This periodic action ensures comprehensive coverage of all precursors in the sample over time, increasing the total number of detectable precursors while maintaining manageable spectral complexity during each scan cycle.
3Productivity
If ion packets are fragmented in parallel to increase throughput, then analysis speed improves, but precursor selection resolution deteriorates
Solution Approach 1:
The patent segments ions into discrete packets with defined m/z boundaries using a scanning device. Each packet is independently fragmented and detected, enabling parallel processing of multiple precursor groups. The segmentation maintains sharp precursor selection by using physical boundaries in the scanning device, achieving both high throughput through parallelism and high resolution through precise packet definition.
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 throughput and resolution of tandem mass spectrometry, enabling more accurate identification and separation of co-eluting analytes, even in complex samples, by controlling fragmentation energy and using high-resolution analyzers like Orbitrap or TOF mass analyzers.
Implementation Method 1
using an all-ion analyzer such as a time of flight (TOF), Orbitrap or Fourier Transform Ion Cyclotron Resonance (FTICR) analyzer
Implementation Method 2
Fourier Transform Ion Cyclotron Resonance (FTICR) analyzer
Implementation Method 3
Selection/isolation of the suitable precursor ion is typically achieved by a quadrupole mass filter
Implementation Method 4
Fragmentation of the selected precursor may be achieved, typically, through collision of the precursor ion with gas
Data Source
AI summary
A method of tandem mass spectrometry is disclosed. A quasi-continuous stream of ions from an ion source (20) and having a relatively broad range of mass to charge ratio ions is segmented temporally into a plurality of segments. Each segment is subjected to an independently selected degree of fragmentation, so that, for example, some segments of the broad mass range are fragmented whilst others are not. The resultant ion population, containing both precursor and fragment ions, is analyzed in a single acquisition cycle using a high resolution mass analyser (150). The technique allows the analysis of the initial ion population to be optimized for analytical limitations.